wastewater disposal and water supply preliminary report woodlane

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constructed Drawing 91632/WT1, the plant comprises the following major components (see Appendix P Photos 29 and 30): 2 x 22kL water storage tanks 2 x Grundfos Hydromaxi CR4-60,1.1kW with Danfoss VF Drive water booster pumps 1 x flocculation tank 2.6m height x 1.8m diameter 1 x 2244-4 fibreglass filter tank and filter media 1 x chlorine doser Flex-Flo Model A114-4 Pump feed at 4.8G/day 3 x doser pumps 240V 50Hz Premia 75, for sodium hypochlorite, 0.95L/hr 2 x 25L Flocculant 9423 1 x 5L Polyelectrolyte 1 x 25L Caustic (NaOH) 20% 1 x 25L Chlorine 1 x air compressor Tornado 21025 Nominal flowrate of the plant is set at 45L/min, the caustic and polyelectrolyte chemicals are added for pH correction and flocculation/coagulation of water, and sodium hypochlorite added for the disinfection of the filtered water. The current servicing of the water treatment plant equipment is supposedly undertaken by Abtech about every 3 months, although there haven’t been any records to justify that this was done. A typical maintenance schedule of the plant issued by Abtech is attached in Appendix L, and it can be seen from the schedule that a daily check is required for most items, although again it is not clear if this has been carried out due to the lack of any records. Nonetheless from Council’s collection of documents there have been some loose records of filled-in clarification plant log sheets, however they are inconsistent and random and do not appear to be validated. A typical template of the log sheet has been attached in Appendix M for reference. The topping up of sodium hypochlorite solution is undertaken separately by SA Water twice a week, although they have indicated that they would prefer to cease providing this service. A typical weekly chemical dosage sheet filled in by SA Water is attached in Appendix N, dated 2 July 2007. These records have Woodlane Wastewater Disposal and Water Supply Preliminary Report Wallbridge & Gilbert/070250rp002RevB/January 2008 Page 21
een sourced from SA Water directly and it may be a concern that Council does not keep a record of these dosage sheets, being the owner of the water supply scheme. It appears that Council had once made an attempt to establish a formal contract with SA Water for the full maintenance of the water supply system, taking effect from 9 March 2001 for a period of 24 months. An Agreement No. 544 was drafted by Council but was never formalised, putting into question the credibility of the current services provided by Abtech and SA Water without the presence of any contractual terms. In October 2004 GHD Pty Limited submitted a review report to Council for the Woodlane Water Treatment Plant to provide an assessment of whether the existing system is suitable for the supply of treated water to the sub-division and shack area. In the report it was mentioned that there had been periods of poor water supply quality, stemming from a single incident when there was a low level in the sludge storage tanks at the treatment plant, causing settled sludge to enter the water supply network. This could well be caused by the lower level of the filter tank outlet than the sludge tank inlet (refer Drawing 91632/WT1), although this may need further investigation to verify. A capacity assessment was also undertaken and included in the GHD report, and from its review it is verified that the river supply pump with 65kL/day capacity is able to adequately supply the 41 allotments in the sub-division (including the toilet block) and 18 shacks, although GHD calculations are based on 40 lots and 20 shacks instead and with a seemingly high yield of 400L/person/day. W&G believes that an average daily flow of approximately 30KL/day would be more appropriate with a peak daily load of 45KL/d. This is based on 41 subdivision lots @ 2.3 persons/lot @ 220L/person + 18 shacks @ 2.3 persons/shack @ 220L/person = 30kL/day, which represents approximately 46% of the river pump capacity (65KL/day). At the average daily flow this would equate to an 11ML/a demand. Even if the peak flow was adopted this would relate to 16.5 ML/a. Woodlane Wastewater Disposal and Water Supply Preliminary Report Wallbridge & Gilbert/070250rp002RevB/January 2008 Page 22
Page 1 and 2: WASTEWATER DISPOSAL AND WATER SUPPL
Page 3 and 4: CONTENTS (continued) 5. APPENDICES
Page 5 and 6: 1. PROJECT APPRECIATION 1.1 INTRODU
Page 7 and 8: The key information deficiencies id
Page 9 and 10: esponsibilities of each party requi
Page 11 and 12: 4. Aquatec-Maxcon Pty Ltd (Aquatec)
Page 13 and 14: 2. SEWAGE DISPOSAL SCHEME 2.1 Sewer
Page 15 and 16: 2.1.2 Capacity Assessment To determ
Page 17 and 18: Table 5 - System Capacity Breakdown
Page 19 and 20: 2.2.2 Irrigation Class B treated ef
Page 21: 3. WATER SUPPLY SYSTEM 3.1 GENERAL
Page 25 and 26: with a view to decommission the pla
Page 27 and 28: 4. ISSUES AND RECOMENDATIONS 4.1 SE
Page 29 and 30: APPENDIX A SECON Consulting Enginee
Page 31 and 32: APPENDIX C Sewer Pump Curves Woodla
Page 33 and 34: APPENDIX E Sewage Capacity Assessme
Page 35 and 36: APPENDIX G DH Approval December 199
Page 37 and 38: APPENDIX I DH Approval 17 December
Page 39 and 40: APPENDIX K Abtech WTP Specification
Page 41 and 42: APPENDIX M Abtech Plant Log Sheet W
Page 43 and 44: APPENDIX O SA Water Main Layout Woo

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