9. Water Quality Discharge Monitoring Programme (WQDMP

Condition 174 of the A2N resource consent details the requirements of the WQDMP. These are addressed as follows.

9.1 Sampling locations

The sampling locations within the CSA are identified in the SSESCPs for the Mt Eden Enabling Works.

Typically, the daily sampling will be undertaken at the outfall of each sediment retention device (SRP, Decanting Earth Bund or containerised device). The weekly sampling will be undertaken at the lowest stormwater manhole within or immediately below the CSA.

9.2 Monitoring parameters

9.2.1. Daily

Daily sampling and measurement will be made of:

Water clarity (cm) Turbidity (NTU) pH

9.2.2. Weekly

Weekly sampling and measurement will be made of:

Total Suspended Solids g/m 3 Total recoverable copper g/m 3

Dissolved copper g/m 3

Total recoverable zinc g/m 3 Dissolved zinc g/m 3 Total petroleum hydrocarbons g/m 3 Ammoniacal nitrogen g/m 3 Nitrate nitrogen g/m 3

9.3 Monitoring methods

9.3.1. Daily

The method of daily monitoring will depend on the sediment retention device utilised.

For the majority of devices this monitoring will be undertaken manually with a grab sample taken at the outlet.

For the measurement of clarity this outflow will be collected in a 20L bucket, with the clarity then measured using a 100mm black disk.

The turbidity will be measured utilising a handheld turbidity meter.

The pH will also be measured using a handheld pH meter.

This monitoring will be recorded on daily record sheets detailing the following information:

Visual check of influent and effluent water clarity, pH, presence/absence visible TPH (e.g. conspicuous oil or grease film, sheen or odour), flocculant type and volume used, dosing system operation; Water clarity; Turbidity; pH; Record any notes for maintenance or additional information (e.g. ordering additional flocculant supplies); and Record of daily volume of chemicals used.

9.3.2. Weekly

Weekly sampling will be undertaken by retrieving a sample(s) of outflows from the lowest stormwater manhole within or immediately below the CSA.

This sample(s) will be forwarded to an accredited laboratory for testing of:

Total Suspended Solids g/m 3 Total recoverable copper g/m 3 Dissolved copper g/m 3 Total recoverable zinc g/m 3

Dissolved zinc g/m 3 Total petroleum hydrocarbons g/m 3 Ammoniacal nitrogen g/m 3 Nitrate nitrogen g/m 3

9.4 Trigger levels

The initial trigger levels for discharges from the site are:

9.4.1. Daily parameters

A minimum water clarity for all discharges of 10 cm or greater measured with a black disc pH between 5 and 9; and No visible total petroleum hydrocarbons (TPH) - sheen or odour.

The trigger for turbidity will be determined following the first month of sampling.

9.4.2. Weekly parameters

The initial trigger values for the weekly parameters are taken from the Water Quality Assessment prepared by Golder Associates (NZ) Limited, dated December 2014.

These initial trigger levels took into account dilution within the receiving environment, being Motions Creek. This consideration resulted in trigger levels being related to the flows within Motions Creek at the time of the discharge. Specifically, the Water Quality Assessment states that the trigger levels for discharges from the Mt Eden CSA are 25 x ANZECC 95% Freshwater during low flow (being 25 L/s) and 100 x ANZECC 95% Freshwater all other times

The flow within Motions Creek at the time of discharge will be determined from the Auckland Council continuous flow recorder on Motions Creek (ARC site 8104).

Table 9-1: Initial Trigger Values

Initial Trigger Value

Chemical / Parameter Low Flow (25L/s at Motions Creek) Total Suspended Solids 50 mg/m 3 for 95% of the time Total Recoverable Copper 35 mg/m 3

Dissolved Copper 35 mg/m 3

Total Recoverable Zinc 200 mg/m 3

Dissolved Zinc 200 mg/m 3

Flows > than low flow Notes

50 mg/m 3 for 95% of the time 140 mg/m 3

140 mg/m 3

800 mg/m 3

800 mg/m 3

Water Quality Assessment

25 & 100 x ANZECC 95% Freshwater 25 & 100 x ANZECC 95% Freshwater 25 & 100 x ANZECC 95% Freshwater 25 & 100 x ANZECC 95%

Total Petroleum 15 mg/m 3

15 mg/m 3

Freshwater ARC TP10

Hydrocarbons Ammoniacal Nitrogen >1.0 and ≤3.5 (mg/m 3 ) >1.0 and ≤3.5 (mg/m 3 ) MFE (2014), Attribute State

B Nitrate Nitrogen >0.03 and ≤0.4 (mg/m 3 ) >0.03 and ≤0.4 (mg/m 3 ) MFE (2014), Attribute State

B

9.5 Monitoring reports

The monitoring reports outlined in Sections 9.5.1-9.5.3 below will be prepared and forwarded to Auckland Council (Team Leader Central Monitoring).

9.5.1. Initial monitoring report

Within eight weeks of monitoring commencing an initial report outlining:

A summary of the monitoring results to date; An interpretation of those results and suggestions for improvement to the site operations were required; A programme for ongoing monitoring including the reporting of results; and Water treatment plant maintenance programme.

9.5.2. Non-conforming result report

Within five working days of receipt of sample results showing contaminants exceeding the trigger levels set out in Section 5.4 of the FTMP, an investigation will be undertaken to determine why exceedances were detected and to identify any additional source controls or treatment required.

The results of this investigation will be sent in a report format to Auckland Council (Team Leader Central Monitoring).

9.5.3. Annual monitoring reports

An annual report will be prepared and submitted detailing:

all aspects of the performance of the EMP relating to this consent; a summary of all revisions and revised sections of the EMP;

details of all inspections and maintenance of the stormwater system for the preceding 12 months; details of and changes to the person(s) or body responsible for the maintenance of site and the organisational structure supporting this process; results and analysis of the preceding 12 months of stormwater monitoring, along with an interpretation of those results and suggestions for improvement to the site operations; and records of any spills or incidents which occurred within the previous 12 months and the response which was undertaken.