Transcript Wastewater Upgrade

Masterton District Council
Homebush Wastewater
Treatment Plant
Neighbours Meeting
29 September 2014
Neighbours Meeting
29 September 2014
Introductions
 David Hopman – Manager Assets
and Operations
 Ian Steer – Special Projects
Manager

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.
Homebush Site
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.
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.
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).
7/28/2014
7/14/2014
6/23/2014
6/3/2014
5/19/2014
5/5/2014
4/22/2014
4/7/2014
3/24/2014
3/10/2014
2/17/2014
Standard = 1800/4000 cfu/100mL
2/3/2014
1/21/2014
1/6/2014
12/16/2013
12/2/2013
11/18/2013
11/4/2013
10/23/2013
10/21/2013
10/7/2013
9/16/2013
9/2/2013
8/19/2013
8/5/2013
E.coli (cfu/100mL)
Figure 1
Masterton WWTP Discharge E.coli Results
(August 2013 - July 2014)
Actual Geometric Mean 95cfu/100mL
2000
1800
1600
1400
1200
1000
800
600
400
200
0
8/11/2014
7/28/2014
7/14/2014
6/23/2014
6/3/2014
5/19/2014
5/5/2014
4/22/2014
4/7/2014
3/24/2014
3/10/2014
Standard = 20g/m3
2/17/2014
2/3/2014
1/21/2014
1/6/2014
12/16/2013
12/2/2013
11/18/2013
11/4/2013
10/23/2013
10/21/2013
10/7/2013
9/16/2013
9/2/2013
8/19/2013
8/5/2013
TN (g/m3)
Figure 2
Masterton WWTP Discharge Total Nitrogen Results (August 2012 - July 2014)
25
Actual Geometric Mean = 11.9g/m3
20
15
10
5
0
7/28/2014
7/14/2014
6/23/2014
6/3/2014
5/19/2014
5/5/2014
4/22/2014
4/7/2014
3/24/2014
3/10/2014
2/17/2014
Standard = 4 g/m3
2/3/2014
1/21/2014
1/6/2014
12/16/2013
12/2/2013
11/18/2013
11/4/2013
10/23/2013
10/21/2013
10/7/2013
9/16/2013
9/2/2013
8/19/2013
8/5/2013
TP (g/m3)
Figure 3
Masterton WWTP Discharge Total Phosphorus Results (August 2013 - July 2014)
Actual Geometric Mean = 1.7g/m3
5
4
3
2
1
0
Figure 4
Ruamahanga River E. coli Levels of Contact Recreation Guidelines
(July 2013 – July 2014)
MfE Action Level (550/100mL)
RUA 2 (Downstream)
MfE Alert Level (260/100mL)
RUA 1 (Upstream)
Red –
Action Zone
700
500
400
Orange –
Alert Zone
300
200
100
6/3/2014
5/5/2014
4/7/2014
3/3/2014
2/3/2014
1/6/2014
12/2/2013
11/4/2013
10/7/2013
9/2/2013
7/1/2014
Green Zone
0
8/8/2013
E.Coli (cfu/100mL)
600
General direction of Homebush
groundwater flow





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.
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.
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.
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
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
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
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.
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.
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.