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Masterton District Council Homebush Wastewater Treatment Plant Neighbours Meeting 29 September 2014.

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Presentation on theme: "Masterton District Council Homebush Wastewater Treatment Plant Neighbours Meeting 29 September 2014."— Presentation transcript:

1 Masterton District Council Homebush Wastewater Treatment Plant Neighbours Meeting 29 September 2014

2 Neighbours Meeting 29 September 2014 Introductions  David Hopman – Manager Assets and Operations  Ian Steer – Special Projects Manager

3  Communicate the findings of the Annual Report on plant performance.  Overview of construction issues associated with the old ponds.  To provide an update on progress with the project and the timeline for the coming year.  To provide neighbours with an opportunity to raise any issues they may have and for appropriate people from within the project team to answer questions.

4 Homebush Site

5 Construction Overview – Work completed  Completed construction, lining and commissioning of Pond 1A (final pond).  Dewatering, de-sludging and landfilling of material from old pond 1.  Construction of the sludge landfill.  Partial de-sludging of old ponds 2 & 3.  Completion of 65% of the irrigation area including automation.  Completion of landscaping.  Completion of all access roads.

6 Operational Overview – Work completed  Fully operational ponds (Ponds 1A, 1B & 2-6).  Diffuser fully operational.  Border strip irrigation from November 2013 to April 2014.  Harvesting and Sale of balage (3 rotations) & production of 1600 bales.  Average irrigation depth of 410mm. (compared to 330mm for Riversdale). Works remaining ◦ Complete de-sludging of old ponds. ◦ Construction of remaining irrigation areas. Outstanding issues ◦ Areas of compaction over some areas of the site are limiting irrigation rates. ◦ Elevated Ground water level preventing construction of all irrigation areas in M zone.

7 For the 2013/14 monitoring period, the following was noted:  The discharged flows complied with the consent requirements on all occasions.  The quality of the discharge complied with the consent conditions.  E. coli concentrations level downstream of the WWTP were below the surveillance level on all occasions except for 6th October when the upstream concentration was also high.  Odour and discharge clarity problems were observed when the last pond was commissioned in May/June.  The discharge is still having a localised effect on in-stream biological community structure in the Ruamahanga River and Makoura Stream (although less that the previous year).

8 Figure 1

9 Figure 2

10 Figure 3

11 Ruamahanga River E. coli Levels of Contact Recreation Guidelines (July 2013 – July 2014) MfE Action Level (550/100mL) MfE Alert Level (260/100mL) RUA 2 (Downstream) RUA 1 (Upstream) Figure 4 Red – Action Zone Orange – Alert Zone Green Zone


13 General direction of Homebush groundwater flow

14  Monitoring wells were drilled at Homebush in 2004 to provide reference data.  Surveys were undertaken to establish levels of the wells and the groundwater.  A number of errors (survey, interpolation of data and change of datum) have now been identified.  The design of the border strips located over the old ponds was based on incorrect groundwater level information.  These errors only became apparent when the contractor began de-watering of the old ponds and preparing for construction of the border strips in the M zone.

15 Can Council take legal action?  Consultant for initial survey engaged directly by Council.  Information supplied to Beca in good faith.  Subsequent surveyor engaged by Beca used same base level information for wells.  Minor groundwater irregularities were noted during construction but not considered significant.  Legal advice is it would be difficult and costly to prove a case against any of consultants or contractors involved.

16 The current situation  The design includes a factor of safety of 30%. This was considered prudent design to address potential risks.  Without the M Zone the treatment plant has no safety margin.  The Consent allows to increase irrigation from 10 mm/d to 20 mm/d after 2 years operation if it can be shown that all operational targets can be exceeded.  After one irrigation season we are not currently in a position to confirm that 10 mm/d can be sustainably exceeded.  The Council is required by the consent to undertake a technical review of options to further reduce discharges to the river.

17 The range of options to utilise the M Zone and reduce the potential irrigation area shortfall include  Do nothing  Increase height of M1 to M3  Import fill to raise height of M4 to M10  A wetland treatment system in M4 to M10  Infiltration basin system in M4 to M10  Install cut-off drain to existing design  Design new cut-off drains  Open swales to capture groundwater  Spray irrigation of M1 to M3  Abandon M4 to M10

18 A range of further options to address the potential irrigation area shortfall include  Do nothing  Extend irrigation onto adjacent Council land  Purchase additional land for irrigation  Construct a tertiary treatment plant to supply Fonterra standard water to Council dairy farm  Extend drip irrigation around the site  Ground water pumping  Pipeline under river to supply irrigation water to adjacent farm

19 Recommendation Complete M1 to M3(giving a design factor of safety of 15%), then adopt one of the following four options:  Do nothing  Construct a wetland  Extend the border strip irrigation system to the Homebush dairy farm  Install a tertiary treatment plant to produce irrigation water that meets Fonterra standards


21 The way forward  Start negotiations with Hoppers regarding completing M1 to M3. A decision to proceed will be subject to the outcome of these negotiations.  Initiate discussions with GWRC regarding additional options and consent variation requirements.  Begin the process to evaluate the options to address the irrigation shortfall in conjunction with the affected parties.

22 The way forward - Programme  Complete construction of irrigation areas that can be constructed – This summer.  Option evaluation - data collection/treatment trials – Underway.  Option evaluation – Workshop with affected parties – proposed around March.

23 Queries and Concerns During Construction  All queries or concerns should be directed to MDC.  Calls/contact are logged and directed to Ian Steer.  Ian discusses/actions with the appropriate parties.  Action is taken as appropriate, the call closed off and contact made with the person who contacted MDC.

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