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6. Monitoring Requirements
6.1 Dust Monitoring
The overall approach to dust control for the main works is based on visual monitoring combined with targeted ambient dust monitoring; good management of the construction areas; and a rapid response to any of the triggers outlined in Sections 6.3.2 or 6.3.4, or complaints received. Good practice focusing on proactive measures will aid in avoiding significant dust emissions, however if dust emissions do occur, the monitoring will help to identify such occurrences and enable a prompt response.
6.2 Visual Inspection and Monitoring Methods
Visual monitoring of all construction areas will be undertaken by the Environment and Sustainability Manager (or delegated person) on a daily basis, or more frequently if conditions change. This type of monitoring relates to the control measures described in Section 5 of this AQ DWP and will include proactive measures to avoid dust emissions.
Table 6-1 below describes the visual dust monitoring activities to be undertaken during construction. Outcomes of visual inspections are to be recorded in the Air Quality Log (log sheet template provided in Appendix D).
Table 6-1: Visual Dust Monitoring Programme
Monitoring activity
Check weather forecasts for strong winds (winds that may exceed the trigger levels described in section 6.3.4) and absence of rainfall to plan appropriate work schedule and dust management response.
Inspect land adjacent to the site, construction exits and adjoining roads for the presence of dust deposition and/or accumulation of dust material.
Observe weather conditions including wind and rain via observations and data outputs from weather stations.
Inspect all exposed un-stabilised surfaces for dampness and that the extent of those areas is being minimised.
Inspect stockpiles for dampness and height of no more than 3°m (or enclosure, covering or stabilisation where required).
Inspect dust generating activities for effectiveness of dust management measures and avoidance of visible dust emissions beyond the boundary of the site.
Inspect watering systems (sprays and water carts) to ensure equipment is maintained and functioning to effectively dampen exposed areas.
Monitor dust generating activities and water application rate (for effective dampening).
Inspect wheels of all trucks exiting the Site to public roads for evidence of tracked material (to be washed and removed as required)
Check for dust on local roads being used to access the site.
Frequency
Daily
Twice daily
Daily and as conditions change
Daily and as conditions change
Daily and as new activities commenced
Daily and as new activities are commenced
Weekly
In winds over 5 m/s (1-hour average)
All truck departures
Daily
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Monitoring activity
Inspect vehicle exits to ensure that wheel inspection and washing is effective and dust or sediment laden water is not being tracked off site by vehicles.
Inspect sealed vehicle access routes within the Site for deposition of material (to be removed via vacuum sweeper truck)
Inspect spray coating application locations for potential spray drift beyond Site
Monitoring that water sprays/fogs are being operated when crushing activities are being undertaken, and that control measures to minimise dust from drilling when setting charges are being implemented and effective.
Frequency
Daily
Daily
Daily and as new activities are commenced
When crushing activities are being undertaken.
6.3 Instrumental Monitoring
6.3.1. Dust Monitoring
Continuous instrumental dust monitoring will be carried out at representative locations adjacent to sensitive areas when in the vicinity of dust generating activities. It is expected that at least three dust monitors are to be used to monitor dust from the site, in accordance with Condition 224 (i) of the A2N resource consents.
The locations of the two monitors initially installed to monitor dust from the site are as follows:
At the Mediaworks building at the corner of Nikau Street and Flower Street adjacent (to the north of) the proposed portal location. This site is intended to monitor particulate levels downwind of the Mt Eden ACZ in prevailing southwest winds. At the existing Mt Eden Station platform. This site is intended to monitor particulate levels adjacent to residential and commercial activities on Akiraho Street. This monitor will be relocated prior to deconstruction of the station platform and adjacent structures.
An additional monitor is proposed to monitor dust near sensitive receptor locations adjacent to earthworks or other dust generating activities along the NAL corridor. This monitor is intended to be moved as works progress along the NAL.
The location of the monitors will be re-evaluated by the Environment and Sustainability Manager (or delegated person) with advice from the Air Quality subject matter expert, and potentially moved, as the construction stages progress and the location of dust generating activities shifts. For example, the Mt Eden station platform
As required by condition 227 of the A2N resource consents, ambient dust monitoring will commence prior to activities that have the potential for significant dust emissions. The two initial dust monitors described above have been commissioned as a consequence of the Mt Eden demolition and enabling works. The third monitor will be required to be commissioned prior to commencement of bulk earthworks or other activities with a potential for significant dust emissions associated with the NAL modification works.
Particulate instrumental monitoring for the main works will include:
Continuous instrumental monitoring of dust concentrations; Calculation of 1-hour average concentrations from real-time monitoring data;
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Remote display of real-time particulate data (e.g. via the internet); Provision for alarms on 1-hour average concentrations measured above dust trigger levels (visual and/or via internet, email and mobile phone); Recording/logging of monitoring data; and The monitors shall be located in accordance with AS/NZ 3580.1.1:2007 Method for Sampling and Analysis of Ambient Air –Guide to Siting Air Monitoring Equipment, except where the presence of buildings or structures in the urban environment precludes complete accordance.
Two Dust Profiler particle counter monitors, manufactured by Aeroqual, have been installed to monitor dust at the site. The third monitor is likely to be of the same model but other monitor options that meet the requirements of the CRL designation and resource consent conditions include:
Remote nephelometers; or Beta attenuation monitors.
6.3.2. Dust Trigger Levels and Alerts
Dust monitoring results are to be compared with trigger levels to indicate where dust levels may have the potential to cause adverse air quality effects and where modification to dust management measures may be required to avoid this outcome.
In the first instance, trigger levels published
by the Ministry for the Environment (MfE) 2 are adopted as operational dust trigger levels. In the event of monitoring results exceeding the trigger level, response actions are to be taken as outlined below. The trigger level values are described in Table 6-2.
Table 6-2: Dust Trigger Levels
Monitored parameter Trigger Level
Instrumental dust monitoring* MfE recommended trigger values for TSP concentrations: 200 µg/m 3 (rolling 1-hour average)**
OR
MfE recommended trigger values for PM 10 concentrations: 150 µg/m 3 (rolling 1-hour average)**
Dust emissions and deposition
Visible dust emissions beyond the boundary of the site Evidence of dust on windows or cars (a finger run down the glass leaves a clear line) Dirt on clean washing *The dust monitoring trigger levels should be updated to reflect the method of monitoring employed, if required (refer below). ** The MfE recommended trigger values do not relate specifically to rolling averages, which are specified in this case to provide instantaneous feedback on dust levels.
The dust monitoring trigger levels should be reviewed through regular (at least monthly) review of monitoring results. The regular review should include comparison with:
The trigger alerts specified in Table 6-2;
2 Ministry for the Environment. 2016. Good Practice Guide for Assessing and Managing Dust: Ministry for the Environment.
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A review criterion for 24-hour average particulate TSP concentrations of 60 µg/m 3 for TSP or of 50 µg/m 3 for PM 10 (if TSP is not measured) 3 ; Visual monitoring records; Dust complaints.
If review of monitoring results indicates the triggers specified in Table 6-2 have not provided suitable advance indication of potential adverse air quality effects, the triggers may require modification.
The monitoring equipment will be set up with text alerts to key personnel in the relevant work zone, when dust concentrations exceed the trigger values set out in Table 6-2. At a minimum this will include:
The Project Manager; The Environment and Sustainability Manager; The Construction Manager; and Site Engineer.
If main works personnel change, the Instrument Technician will be contacted to update the alerts.
If a dust trigger alert is sent, one of the above staff members will immediately (within 30 minutes) respond and investigate the cause of the alert. This investigation will:
Determine if the alert is real and not caused by equipment malfunction; and Identify the source of dust and check to see that all of the required mitigation measures are being implemented.
If it is determined that construction activities are the cause of dust, and that mitigation measures outlined in Section 5 of this AQ DWP are not effective for controlling dust, the contractor will implement the dust contingency procedures outlined in Section 5.8 of this AQ DWP. If these measures fail to effectively manage dust to acceptable levels, works shall be halted until it can be determined why dust emissions are occurring and what additional mitigation measures are required to control ambient dust to acceptable levels.
The findings of the investigation will be recorded in the Air Quality Log (refer to Section 9.1 of this AQ DWP).
6.3.3. Meteorological Monitoring
Continuous instrumental monitoring of local weather conditions will provide information for dust management. A meteorological station that can continuously measure the following parameters is to be installed at the Site:
Continuous instrumental monitoring of wind speed and direction; Recording of 1-minute and calculation of rolling 1-hourly averaged data; Provision for alarms on wind speed data measured above wind speed trigger levels (visual and/or via internet, email and mobile phone); Remote display of real-time meteorological data (e.g. via the internet); and
3 The MfE Good Practice Guide (2016) does not recommend a 24-hour average trigger for PM 10 and the threshold concentration for 24-hour average PM 10 concentrations specified in the National Environmental Standards for Air Quality has been specified as the PM 10 review criterion (where TSP concentrations are not measured). Page 30 | Mount Eden Enabling Works
Recording/logging of monitoring data.
Additionally, at least one meteorological station that can continuously measure rainfall, relative humidity and temperature is to be installed.
Where practicable the monitor(s) shall be located in accordance with AS 3580.14 -2011 Ambient Air –Guide for the Measurement of Horizontal Wind for Air Quality Applications. It will preferably be located to avoid adjacent buildings and other obstructions, where possible.
In the absence of on-site weather monitoring data, information of current and preceding wind conditions may be obtained from:
Weather observations from other CRL works areas (if available); Weather observations from other weather stations in Central Auckland (if available); Current wind observations are displayed by the Met Service at www.metservice.com.
6.3.4. Wind Speed Trigger Dust Alerts
The Trigger Levels proposed for wind speed measurements are detailed in Table 6-3.
Table 6-3: Wind speed trigger levels
Discharge
Wind speed
Trigger Level
Wind warning level: − 5 m/s (1-hour average) − 10 m/s (1-minute average occurring twice in 20 minute period)
In the event that wind speeds exceed the trigger values set out in this AQ DWP, text alerts will be sent to nominated main works personnel in the relevant work zone. As a minimum, the nominated personnel will include:
The Project Manager; The Environmental and Sustainability Manager; The Construction Manager; and The Site Engineer.
If 1-hour average wind speeds exceed 5 m/s then visual monitoring of the work area will be undertaken and recorded in the air quality log, to ensure that all appropriate mitigation outlined in this AQ DWP is being implemented and are effective.
6.3.5. Alternative Management Approach
There is the potential that continuous instrumental measurement of particulate concentrations may be influenced by either background particulate emission sources (not associated with the Mt Eden Main Works, such as other construction activities, domestic home heating or motor vehicle emissions) or rainfall/high humidity conditions that can affect dust monitoring instruments.
Previous experience at other CRL construction sites has shown that comparison of continuously measured ambient particulate concentrations with defined trigger levels may not always be indicative of adverse dust effects or a potential for dust nuisance experienced beyond the site boundary.
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If investigations of exceedance trigger levels establish that trigger events are not associated with onsite dust generation, an alternative dust risk assessment approach can be implemented. In that instance and if required by the Environment and Sustainability Manager in consultation with the Auckland Council Monitoring and compliance team, the following alternative approach will be taken:
A response to individual dust trigger alerts in accordance with Section 6.3.2 will not be mandatory and instrumental dust monitoring results will instead be reviewed against the trigger levels specified in by the Environment and Sustainability Manager (or delegated person) on a daily basis. Visual dust inspections are to continue in accordance with Section 6.2. If identified by the Environment and Sustainability Manager as a result of a review of instrumental dust monitoring results, visual inspections may be required at an increased frequency. Dust risk is calculated each morning by site engineers in accordance with Section 5.1 and Appendix B and used to inform appropriate management procedures.
6.4 Monitoring Data
All monitoring data from the dust monitors and the on-site meteorological station will be available to main works staff on-line, and electronically recorded for future reference.
The dust monitoring equipment and meteorological equipment will require periodic maintenance and calibration checks. These will be done at a frequency and as per manufacture specifications by either site personnel, who have received appropriate training, or an Instrument Technician.
Unless the instrument recommends a higher frequency, at least quarterly maintenance and calibration will be carried out by a qualified Instrument Technician familiar with the equipment installed.
In the event that there is an equipment malfunction, or the equipment needs to be relocated for some reason, then the Instrument Technician will attend to this. If equipment malfunction results in on-going dust emissions (during the malfunction), the equipment is to be repaired, replaced or other measures are to be taken to minimise those emissions within 24 hours of the malfunction being identified.
6.6 Odour Monitoring
Odour monitoring (observations) will be undertaken when it is considered likely that odorous material may be encountered (such as contaminated soil materials) during excavations. The decision to undertake monitoring by a suitable experienced odour observer will be made by the Environment and Sustainability Manager.
The frequency of odour monitoring will be dependent on the nature/scale of the source, location in relation to sensitive receptors, and meteorological conditions during exposure. Odour observations will occur:
When potentially odorous contaminated material is excavated and loaded onto trucks; and When odour complaints have been received or odour is detected by main works staff.
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The Environment and Sustainability Manager will ensure that a trained odour scout is available to undertake odour observations as required.
Monitoring will involve the odour observer being positioned downwind of the works and assessing odours on the intensity scale set out in Table 6-4. Where odours are identified as being “Distinct” and above, and the odour characteristic unpleasant, mitigation measures will be implemented. All observations will be recorded in the Air Quality Log (refer Section 9.1 of this AQ DWP).
Table 6-4: Odour Intensity Scale
Intensity scale
0
1
2
3
4
5
6
Criteria
No odour
Very weak
Weak
Distinct
Strong
Very strong
Extremely strong
The odour observer will reassess the level of odour once the mitigation measures have been implemented. If the odours are still ‘Distinct’, further mitigation will be implemented, and / or the works halted until more conducive meteorological conditions are present, i.e. not blowing towards the sensitive receptor.
If it is suspected that sources upwind of the works are responsible for any odour, the odour observer shall make appropriate observations and document these also.
As exposed odorants may potentially also present health risks, the procedures outlined in Section 7.1 of the Contamination DWP for unexpected discovery of contamination should also be followed.
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