Water Services Training Group

1. Water Services Training Group 14th Annual Conference New Decade – New Challenges 9th September 2010

2. Gort Waterworks Upgrade Liam Gavin Senior Engineer, Water Services Galway County Council

3. Background • Gort – population 3,000 • Gort Water Works – built in 1930’s • Original works consisted of • Raw Water balance Tank • 3 Slow Sand Filters • Clear Water Tank

4. Sand Filters and Raw water Tank

5. Issues • Historical Treated Water Quality • Colour......................................... 40 – 70 mg/l • Iron............................................. >0.2mg/l • Manganese.................................. >0.05mg/l • THM’s.......................................... >100mg/l • Turbidity...................................... >1mg/l • Cryptosporidium Risk Score......... 167 • Public Complaints • Chlorine Contact Time……………. 22 mins

6. Issues - continued • Operational Problems • Filter capacity – 500m3/d • Throughput – 1400m3/d • Maintenance requirements • Proposed Gort Regional Water Supply Scheme at Preliminary Report Stage • Boil Water Notices • Due to Historical Issues Gort waterworks was included in EPA Remedial Action List.

7. Response • Implement Immediate Measures • Improve Chlorine Dosing • Provide Chlorine Dioxide Dosing • Consultants Engaged to • Carry Out Cryptosporidium Risk Assessment • Develop Proposals for Short term Solution • Address Network Deficiencies • Raw Water Rising Main • Distribution Network Improvements

8. Statement of Need • Provide treated water complying with E.C. (Drinking Water ) (No.2) Regs. 2007 • Reduce Cryptosporidium Risk (167 – Very High Risk Class) • Restore Public Confidence in Water Quality • Address Capacity

9. Options • Three options for water treatment identified • Option 1:- Upgrade existing slow sand filters • Option 2:- Construct new waterworks on new site • Option 3:- Upgrade the existing water works on the existing site. • Need to maintain existing supply.

10. Option 1 • Upgrade the existing slow sand filters • Requires increased sand filter area from 120m² to 350m² to get sufficient throughput. • Insufficient space available around existing 0.16ha site. Would need to purchase an area equivalent to existing site. • Sand filtration alone not adequate to remove colour from raw water. Additional treatment processes involving coagulation and clarification would be needed.

11. Option 2 • Construct new water works on new site • Would address all water quality issues • No site in Council ownership in Gort with suitable planning and land use matrix • Increased cost of site purchase with unacceptable delays to progress an urgent project.

12. Option 3 • Upgrade the existing waterworks • Site very restricted for expansion or working around • Raw water balance tank – proportionally large. Decommission and construct new units within? • Slow Sand filters undersized. Abandon and reuse? • Clear water tank inadequate contact time and poor structural condition

13. Option 3 - continued • Upgrade the existing waterworks • Existing site in Council ownership. Work on upgrade could proceed immediately • Use of site established and accepted. • Good location for water treatment and convenient for delivery of service to public • Option 3 is preferred option

14. Original Site layout Clear Water Tank Slow Sand Filter Raw Water Tank

15. Original Site layout

16. Proposed Site Layout Raw Water Tank Wash Water Tank UV Disinfection Unit Sludge Tank DAF Unit Rapid Gravity Filters Upgrade Clear Water Tank Control Building Break Out Wall

17. Option 3 - Upgrade Decommission Old Raw Water Tank. Construct: New Raw Water Tank Control Building Flocculation Tanks DAF Unit Raw Water Tank DAF Unit Control Building

20. Option 3 - Upgrade Convert Slow Sand Filter No.1 to 2 Rapid Gravity Filters Rapid Gravity Filters

21. New Rapid Gravity Filters

22. Option 3 - Upgrade Convert Slow Sand Filter No.2 and part of No.3 to Filter Washwater Tank Wash Water Tank

24. Option 3 - Upgrade Convert part Slow Sand Filter No.3 to Sludge Storage Tank Sludge Tank

25. Sludge Storage

26. Option 3 - Upgrade New Chemical Storage Area Chemical Storage Area

29. Option 3 - Upgrade Upgrade Clear Water Tank and address problems relating to concrete, leakage and retention time Construct new baffle curtains New inlet pipe

30. Structural Defects

31. Upgrade Clear Water Tank and address problems relating to concrete defects, leakage and retention time Tank Lining and Baffle Curtains

33. Achievements Drinking Water quality compliant with E.C. (Drinking Water ) (No.2) Regs. 2007 Cryptosporidium Risk reduced to < 50, Low Risk Class Raw and Treated Water Quality monitoring on site Public Confidence Condition of Structures upgraded and Leaks eradicated Interim Solution in place until Gort RWSS is provided Plant Upgrade provided in 26 weeks

34. Costs • Capital Costs • Funded under the Water Services Investment Programme by the DOEH&LG (81%) and Galway County Council (19%) • Total capital cost €760,000 • €422 per m³ of treatment capacity

35. Costs - continued • Operating Costs Gort Waterworks • Current - €0.37/m³ before upgrade • With upgrade - €0.69/m³ • Operating Costs Galway County range from €0.20/m³ - €1.50/m³ • Operating Costs nationally for equivalent plant size is €1/m³

36. Summary • Effective use of an existing resource • Compliant, safe, wholesome drinking water • Certainty of quantity and quality • Value for money • Public satisfaction/confidence • Support from DOEH&LG through Water Services Investment & Remedial Action Programmes