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Ron Pilgrim ConsultingWaikato Regional Council 21 August 2020Private Bag 3038Waikato Mail Centre Hamilton 3240

Attention: Mr Ben Murphy

Dear Ben

RCP Review of Golder Report Upgrade of Odour Extraction and Treatment Systems for Tuakau Proteins LimitedAs discussed, I include my evaluation of the July 2020 Golder Upgrade Report as requested. I also include an Addendum which comprises extracts from the Peer Review of the Golder Associates Upgrade Report by Terry Schulz of The Odour Unit. The Peer Review was received by me on 14 August 2020. I have also included several comments following the Addendum.

If you have any queries please get back to me.

Yours sincerely.

(Ron Pilgrim)

Air Quality & Air Pollution Control Consultant

Postal Address: 39 Wairere Road, Belmont, Lower Hutt 5010.Telephone: (04) 5692678 Cell Phone: (0275) 816-944 Fax: (04) 5692-789

Email: [email protected]

RCP Review of Golder Report Upgrade of Odour Extraction and Treatment Systems for Tuakau Proteins Limited Received 28 July 2020

To: Ben MurphyResource Officer – IndustryWaikato Regional Council

Introduction

I have evaluated the July 2020 Golder Upgrade Report (the Report) as requested. I note from Section 1.2 of the Report (Report Structure) that the scope of the Report is comprehensive.

I also note that a number measures have been proposed which I either support or support in part There are also some measures proposed which I either don’t agree with, or at least I have reservations about, and in some cases these reservations are based on the lack of supporting information provided. It is also possible that I have not fully understood some of the measures proposed and/or their interrelationship with overall operations. My comments are presented below.

Reference to some matters appears to have been downgraded to barely a mention if included at all although this may be because Golder sees such matters as not being relevant to the scope of this particular review. For example, I would have thought that at least reference to the importance of consistently receiving then processing raw material of good quality was an integral part of TPL’s rendering plant operation, and the inevitable occasional failure in raw material quality is one reasons to have realistic contingency procedures.

The successful commercial and environmental operation of animal rendering processes, especially those located in sensitive areas, is a combination of interlinked parts. These include raw material quality, effective process operation and process containment and process and rendering building extraction ventilation to appropriate odour control equipment. In addition, the provision of contingency measures in case of receipt of poor quality raw materials and plant breakdowns and other malfunctions is very important commercially and environmentally. Contingency measures include redundancy of essential equipment, how existing equipment can be optimised, and provision of process and processing buildings ventilation air extraction to effective odour control equipment or other procedures if issues with the process concentrated sources extraction systems occur.

Provision of contingency measures is included in Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions dated 24 April 2020 and this is discussed at the end of my review.

My specific comments are presented below.

Section 3.1.3 Meal Dryers.

Golders states that both LTR1 and LTR2’s meal dryer exhausts streams are respectively pre-cooled via waste heat evaporator plants (WHE 1 & 2). These (NCG) streams are extracted via a WHE fan which draws the two streams into a common duct, which connects to two shell & tube heat exchangers (in series) and the combined cooled WHE flow to the inlet duct of the Biofilter LTR1 fan (Figure 4). It is considered that arrangement of ducts and fans shown in Figure 4 can be modified to achieve a more controlled balancing of flows between LTR1 concentrated sources, the combined WHE flow and individual WHE flows.

Ron Pilgrim Consulting Comment (RPC Comment): I fully support any measures to optimise and simplify process systems where practicable to do so

2RCP Review of Golder Report Upgrade of Odour Extraction and Treatment Systems for Tuakau Proteins Limited – Final Version- 21 August 2020

Section 3.2.3 LTR1 Equipment & Duct Connections.

Golder states that for the isolated concentrated source extraction systems there are various extraction legs for which they recommend an increase in size as highlighted in Tables 1 and 2. Some concentrated sources are likely to receive insufficient air extraction. Improvements to the existing LTR2/HTR concentrated source system would be achieved by the connection of a new 3.3 m x 360 mm sub-manifold to the existing 360 mm sub-manifold that connects to the pre-cooker (ID no. 4). Then using this extension to connect to the LTR2 decanter and discharge (ID No. 6 and 7). These changes combined with recommended increases in duct sizes listed in Table 1, were assessed using flow distribution model for the LTR2/HTR manifold.

The design of the LTR1 concentrated source main manifold system itself appears reasonable in terms of its ability to have balanced extraction of flows and at adequate flow rates. The benefits on increased duct sizes listed in Table 2 were assessed using flow distribution model for the LTR1 manifold.

RPC Comment: Recommended increase in extraction duct size is supported. Improvements recommended for LTR2/HTR are also supported. Would you please provide more information about the air flow distribution model referred to above including if it is a privately developed model or a commercial model, and in any case comment about it operation and limitations.

Section 3.3.1 Building Air Extraction – Flow Distribution Modelling

Golder notes that a total airflow of 100,000 m3/hour from the 85 kW motor fan should be achievable. Modelling of existing system indicates around 75% of total flow would be extracted from the LTR2/HTR building and 19% of flow would be extracted from the LTR1 building. Table 4 provides air flow modelling results following proposed modifications to the building air extraction system and for a total building air flow of 100,000 m3/hr. Breakdowns are provided in the four box points. Table 5 utilises the results in Table 4 to compare the modelled building air ventilation rates for the existing building air duct and compares to those achieved following proposed modifications. Results confirm proposed changes would provide a far more even ventilation of the different processing areas and also provide more than adequate ventilation of raw bins if employing closable lids and being directly connected the building air system.

RPC Comment: How the building air ventilation extraction system became so unbalanced is explained to some degree in Section 7.0 (Discussion) of the Golder Upgrade Report. Additional to this comment, I also understand that additional relatively large building roof vents were installed and connected to the large fan used for the large biofilter. Golder apparently advised this was likely to have reduced the level of vacuum within the concentrated sources ducts, but it is also possible that there was some blockages or fouling of the concentrated sources system that also reduced vacuums. Since the concentrated sources had been modified over time, the extraction system was probably not operating to design. Progressive build-up of material within the ducting was also suspected. At what point these issues became apparent is not stated but I cannot recall mention being made of such issues in the Golder Reports that formed a part of the current application for the air discharge permit.

I support changes that will optimise air extraction from all significant buildings. In respect to ventilation of raw materials bins employing closeable lids directly connected to the building air ventilation system, such targeted extraction should significantly improve extraction efficiency providing such lids can be appropriately constructed to resist damage when moved to allow off-loading from trucks. Their effectiveness when trucks are off-loading raw materials will also be compromised unless a relatively sophisticated design is developed.

Section 3.3.3 Additional Building Air Ventilation


Golder comments that additional ventilation of building air from process rooms and discharging to atmosphere is proposed for maintaining a healthy working environment within the plant. Reliable estimates of absolute heat energy inputs into each area of the plant are not available. However, based on the type of plant, the total ventilation flows required for environmental control for the LTR2/HTR buildings (including dryer and meal processing) could be 1.5 – 2 times that required for the LTR1 rendering building. Furthermore, the LTR2 dryer/meal room could also require 1.5 – 2 times that of LTR2/HTR rendering hall. A typical process room ventilation rate for maintaining a reasonable working environment is the order of 15 air changes per hour or higher for low temperature rendering plants. The smaller LTR2 dryer/meal room may need a higher rate of approximately 20 air changes per hour. The raw material reception rooms are both relatively large and so direct ventilation of their bins is proposed for odour containment. However environmental cooling air required for the rendering halls could be sourced from these rooms. Given the above, the ventilation of building via roofline stacks were modelled for six stacks in total.

For the scenarios assessed and discharge rates to air, the ventilation of building and cold sources air to the Building Air Biofilter (as per Table 4) was also allowed for. This enabled the effective number of building volume changes per hour and building vacuums to be estimated, as summarised in Table 6 and Table 7.


RPC Comment: I note the reference to the building ventilation model CONTAMW V2 (November 2002). This is a multizone indoor air quality and ventilation analysis computer program developed by the National Institute of Standards & Technology, US Department of Commerce. It is designed to help determine amongst other things building airflows including infiltration, exfiltration, and room-to-room airflows in mechanically ventilated building systems, wind pressures acting on the exterior of the building, and buoyancy effects induced by the indoor and outdoor air temperature difference. It is reasonable to say like all models the quality of the output data is also dependent on the quality of the input data including any assumptions made.

The modelling results indicate that the two rendering halls and the LTR2 dryer/meal processing room (three process areas) may need (emphasis added) additional ventilation for working environment management within the range of 30,000 m3/hr to 100,000 m3/hr in additional the 90,000 m3/hr of building air that could be ventilated to the building air biofilter (which will also receive 10,000 m3/hr of air from the raw material reception halls ex the their bins).

RPC Comment: Firstly, I would appreciate Golder advising if the approximate building volumes specified in the 4th column of Table 5, and in Table 6, are gross volumes (that is, the volume of contained plant etc has not been deducted) or net volumes (the volume of contained plant has been deducted). In addition, can Golder confirm that the volume of air extracted from plant by the concentrated sources systems has or has not been allowed for in respect to building ventilation air flow totals.

I note the comment I emphasised above that “... the two rendering halls and the LTR2 dryer/meal processing room (three process areas) may need additional ventilation for working environment management ...” I therefore presume that the need for additional ventilation air for workplace cooling is far from certain, and in addition, the rate of additional air flow (stated as being within the range of 30,000 m3/hr – 100,000 m3/hr) is equally uncertain.

While it is entirely appropriate to comply with employee health and safety indoor air temperature requirements, I expect that all reasonably practicable measures will be implemented to minimise heat ingress into the working environment. Reference has been made to this at various times in s92 requests for information including ensuring all significant heat emitting plant is appropriately thermally insulated (with insulation that can be regularly washed-down). Would Golder confirm whether or not hot processing plant is appropriately thermally insulated (and if so, to what standard) and if not when will this be fully achieved.

The use of sequential building air ventilation to more effectively utilise building ventilation air, which was raised in s92 requests for additional information and which were ignored, has rated barely a mention in this Report. Reference was limited to the comment “However, environmental cooling air required for the rendering halls could be sourced from these [the raw materials reception] rooms.”1 Would Golder provide a more detailed analysis of how building ventilation air flow including additional air for cooling purposes as necessary could be optimised.

Section 3.3.4 Odour Impact from Building Air Ventilation

In Section 3.3.4, Golder evaluated their proposed option of ventilating rendering buildings to air from 3 m high vents located on building roofs. This discharge would be associated with a measurable residual odour associated with fugitive emissions which escape the concentrated sources systems and from diffuse sources. A odour exposure level (99.5 percentile 1-hour concentration, OU/m3) due to odour emissions from three building air discharge stacks (LTR1 and LTR2/HTR rendering halls and the LTR2 dryer room) was established using the CALPUFF dispersion modelling and use of the Auckland Council CALMET meteorological data sets for 2007 (ARC 2010). CALPUFF modelling was undertaken using the Version of 7.2.1 and the PRIME building downwash settings for onsite buildings.

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RCP Review of Golder Report Upgrade of Odour Extraction and Treatment Systems for Tuakau Proteins Limited – Final Version- 21 August 2020

Odour discharge rates and stack parameters modelled assuming flows of 4 m3/s at 30°C with 700 mm diameter stacks terminating 3 m above roofline. Each stack discharged odour at 5,300 OU/s (16,000 OU/s total odour discharge).

This odour discharge scenario was predicted to create a 99.5th percentile 1-hour concentration of 2 OU/m3 at the most impacted residential dwelling that is off Lapwood road (i.e. 150 m from the rendering plant and adjacent to the eastern site boundary). This impact is the Ministry for the Environment odour modelling criterion for high sensitivity receiving environments and worst case impacts during neutral to stable conditions. The predicted odour exposure at the nearest River Road properties for this scenario are well below this criteria.

In summary, an indicative total odour emission of 16,000 OU/s (5,300 OU/s from each of the three building air discharge stacks) is expected to cause minor levels of rendering odour exposure off-site. This is given that the building air discharge directly to air, would be the primary source of residual rendering odour emission from the site, given the operation of the concentrated sources systems and building air biofilter systems, as proposed in this report.

RPC Comment: Golder states that around 90,000 m3/hour of building air would be ventilated to the building air biofilter (which may also receive as well 10,000 m3/hour of air from the raw material reception halls ex their bins). The example volumetric flow for the three stacks in total of around 12 Am3/s is 43,200 A m3/hour (38,930 Sm3/hour) which gives a combined building air ventilation flow of around 143,000 Am3/hour. Of this, the direct discharge of building ventilation air to atmosphere is around 30% of the total rate of ventilation of the rendering buildings, which is a significant air flow. However, a rate of odour ‘mass’ discharge of 16,000 OU/s from the roof vents in total is quite low and while the indicative odour modelling suggests little issue downwind, more supporting information is required. This includes the basis of how the assumed 16,000 OU/s discharge rate was derived. (Modelling information to be provided should be of the quality expected for an application to WRC for a new air discharge permit.) I doubt that the indicated rate of odour emission would be consistent with fugitive emissions into the factory building(s) if significant issues with the concentrated sources system occurred, especially if the quality of raw materials being processed at the time was poor.

While I appreciate that increasing the rate of ventilation of the buildings by 43,000 Am3/hour greatly assist in providing an improved working environment especially during warm weather, more information should be provided as requested above. This includes the use of sequential building air ventilation to more effectively utilise building ventilation air (for example, Golder’s suggestion that environmental cooling air for the rendering halls could be sourced from these the raw materials reception rooms).

Section 3.4.1 Building Air Biofilter

General comments include if treating ambient building air alone, this bed is capable of treating air flows of 100,000 m3/hr (i.e. a loading at 50 m3air/hr per m3media, and a reasonable upper limit to be 60 – 70 m3air/hr per m3media bed loading.

RPC Comment: I support the comments by Golder but I also maintain that operating up to 70 m3 air/m3 media as a building ventilation air biofilter may be handicapped to some degree by including soil in the bark media due to the increased fines content. It also appears that the construction of the additional large biofilter has ceased – could Golder confirm this is the case, or otherwise.

Section 3.4.2 LTR1 Concentrated Source Biofilter

Golder states the bed is capable of treating pre-cooled concentrate source air flows up to 17,000 m3/hr (i.e. a loading at 35 m3air/hr per m3media. It is understood that biofilters at some plants are designed to


treat concentrated source streams at loading rates of 50 m3air/hr per m3media. Golder recommends use of the more conservative design value of 35 m3air/hr per m3media for the service rendering industry.

RPC Comment: I support the comments by Golder in respect to operating the biofilter as a dedicated concentrated sources biofilter at a loading of no more than 35 m3air/hour per m3media, especially if soil is incorporated in the bark media.

Section 4.1 Design Outcome

Golder states the required outcome of the design of the CSES and dryer NCG extraction system is to enable the routine discharge of rendering building air to atmosphere, as necessary to achieve a safe working environment, while not causing more than minor levels of rendering odours (defined as a maximum predicted 99.5 percentile 1-hour concentration 2 OU/m3) at the site boundaries due to building air discharge.

The discharge of building air should be via a vertical stack with a minimum efflux velocity of 10 m/s. The maximum odour emission rate associated with this building air ventilation can be established by requiring the total emission (OU/s) to cause a maximum predicted 99.5 percentile 1-hour concentration of 2 OU/m3 at the nearest private house (opposite the eastern site boundary off Lapwood Rd). This is predicted using an accepted dispersion modelling approach.

This above strategy requires the design and maintenance of a CSES that targets all significant odour sources, the ability to odorous streams to below 40oC for 99% of the time, and treating the resultant mixed streams via an appropriately sized and operated soil-bark biofilter.

RPC Comment: I have reservations about this design outcome – see my comments in Section 3.3.4 above. These comments relate to the discharge of building ventilation air direct to atmosphere, providing more information in respect to further minimising heat emissions into the working environment, and adopting sequential air ventilation to more effectively utilise building ventilation air (including environmental cooling air for the rendering halls could be sourced from raw materials reception rooms). In addition, the Ministry for the Environment’s current (2016) Odour Modelling Guideline for high sensitivity environments is 1 – 2 OU/m3 depending on atmospheric stability at the 99.9 or the 99.5 percentile2, not just 2 OU/m3. In addition, the appropriate ambient air guideline should apply to all sensitive development outside of the Company’s premises, not just to the “nearest private house”.

I also question the use of the 99.5 (0.5) percentile odour concentration at this location rather than the 99.9 (0.1) percentile. According to Freeman and Cudmore (2002) 3, the 99.5 percentile concentration can provide a useful indication of the potential for chronic (long-term) adverse odour effects, whereas the 99.9 percentile concentration prediction would provide better indication of the potential for acute (short-term) odour impacts. They also say that the 0.1 (99.9) % should be used to assist in the evaluation of modelling results for highly and moderately sensitive receiving environments. In this respect, TPL abuts sensitive development, and at least some of the occupiers of which have experienced significant odour nuisance over some years and are sensitised.

Table 2 of the MfE November 2016 Good Practice Guide for Assessing & Managing Odour is attached for information.

2 The November MfE Report recommends that the guidelines be treated as design ground-level concentrations for one-hour modelling averages as they already include the peak-to-mean ratio adjustment for all source types.

3 Odour Management under the RMA – Technical Background Report. Freeman & Cudmore. MfE N.Z. August 2002. (This report was the technical basis for MfE 2004 Good Practice Guide for Assessing & Managing Odour.)


4.2.1 Target Concentrated Sources Extraction Flows

RPC Comment: Comments noted and accepted.

Section 4.3.1 Building Air Extraction–Raw Materials Bins.

Golder states the raw material bins in LTR1 and LTR2 raw material receipt rooms have estimated volumes of approximately 120 m3 for each line. Installing a closable lid system on the existing raw material bins allows odours within these bins to extracted effectively. The revised building air ducting design indicates extraction rates of approximately 30 volume changes per hour (m3 air/hr per m3 building), and higher. This rate should ensure odours do not build up within the closed bins, or escape as fugitive emissions.

RPC Comment: In Section 3.3.1 indicated support for changes that will optimise air extraction from all significant buildings. In respect to direct ventilation of raw materials bins employing closeable lids directly connected to the build air ventilation system, while these would certainly improve raw material bins ventilation efficiency, such lids would require to be appropriately constructed to resist damage when moved to allow off-loading from trucks. In addition, their effectiveness when trucks are off-loading will be compromised unless a relatively sophisticated design is developed.

Section 4.3.2 Rendering Buildings

Golder states the modified building air extraction/biofiltration system provides an additional layer of protection against significant fugitive odour discharges. The total extraction volume (100,000 m3/hr) is evenly split between the LTR1 and LTR2/HTR rendering halls and the LTR2 dryer/meal processing room as set out in Table 5. Building ventilation rates in the range of 8 to 10 volume changes per hour are believed to be achievable.

RPC Comment: I support any realistic optimisation of ventilation air extraction systems. However, as I comment in Section 3.3.1 it will be useful to see why the 75%/19% imbalance of the LTR2/HTR building and LTR1 building occurred.

Section 4.4.1 Concentrated Source Biofilter

Golder recommends that concentrated source flows are treated via a dedicated concentrated source biofilter. Further, media volumes for these beds are based on the conservative design criteria of 35 m3 air/hr per m3 media. This value was previously established between the Waikato Regional Council and TPL (formerly Lowe Group, Tuakau) as a result of an application for a renewed air discharge consent for


the site in 2009. It has since been applied to a number of rendering plant biofilter designs throughout New Zealand.

RPC Comment: As I said in Section 3.4.2, I support the comments by Golder in respect to operating the biofilter as a dedicated concentrated sources biofilter at a loading of no more than 35 m3air/hr per m3media, especially if soil is incorporated in the bark media.


Golder comments that the building air biofilter currently treats a mix of building and concentrated source air streams. The latter requires long bed residence times and any channelling will readily lead to offsite odours. The building air biofilter can receive relatively high air loading rates, but are more prone to drying out and air channelling problems than dedicated CSES biofilters (which always receive a saturated air stream). The existing building air biofilter is relative close to the nearest neighbours, which is a less an issue when only used to treat relatively low levels of residual odour within a high flow of building air. Except for the air loading rate, all design and operational criteria listed in Table 12 are applicable to the building air biofilter.

RPC Comment: I support removing of concentrated sources from the Building Air Biofilter and being routed to an additional concentrated sources biofilter. Issues with the building air biofilter media drying out especially at higher air loading rates should be solved by installing a purpose-designed humidifier in the inlet duct of the building air biofilter.

Section 5.1.1 HTR Dryer Exhaust Design Change

The current ducting and fan layout for extraction of HTR cooker and LTR2 concentrated sources is an effective design. However, the size of the LTR2 fan and ducting post the LTR2 HX may well need to be increased if the HTR dryer and LTR2 concentrated sources flow are to be treated via a dedicated LTR2 concentrated source biofilter. The use of two dedicated fans (HTR fan and LTR2 fan), or else a single fan downstream of the HX’s is an effective arrangement, enabling these streams to be transferred (in the future) to a new concentrated sources biofilter. Currently these flows combine with the large building air flow and transfer to the large building air biofilter (Figure 3).

RPC Comment: I support combining these streams to be transferred to a new concentrated sources biofilter.

Section 5.1.2 Meal Dryers Exhaust Design Change

One option for improving the above arrangement would be for the common NCG duct to travel directly to the WHE HX (by-passing the non-operational fan and horizontal HX). This would shorten and simplify the existing 400 mm NCG duct and result in an approximately 50 m long section between WHE 1 and WHE HX.

The WHE fan’s 390 mm discharge duct currently connects to 700 mm inlet duct to the LTR1 biofilter fan. For this configuration, it would be better for the WHE fan to force the NCG flow through the WHE HX, whilst the discharge from the latter connects to the biofilter fan inlet. Alternatively, the NCG duct could remain connected to the WHE HX (as per Figure 4), and the WHE fan discharge duct instead connects to the 1300 mm biofilter inlet duct, downstream of the LTR1 biofilter fan.

The second arrangement is probably the best option to employ for enabling LTR1 concentrated sources to be isolated from the LTR2 concentrated source extraction system and for the LTR1 biofilter fan’s extraction capacity to be dedicated to LTR1 concentrated sources. For this, the smaller site biofilter would treat all LTR1 concentrated sources and the total NCG exhaust flows from the site’s WHEs.


RPC Comment: I support any realistic optimisation of ventilation air extraction systems.

Section 5.2.1 Dedicated Vs Combined Concentrated Sources Systems

The key modification to consider is the option of LTR1 and LTR2/HTR concentrated source systems returning to isolated systems. Therefore, having systems connected to their own extraction fan and dedicated cooling systems.

A common concentrated source system is an option, although this would require a larger interconnecting manifold between the two concentrated source systems shown for LTR2/HTR and LTR1. Other site activities need to be investigated to determine the significance of these and whether they are likely to be associated with offsite odour effects.

RPC Comment: My preference is LTR1 and LTR2/HTR concentrated source systems returning to isolated systems.

Section 5.2.2 Design Changes

The recommended design changes for the LTR2/HTR and LTR1 and concentrated source extraction ducts are shown respectively in Drawings 01B and 02B.

Modelled flows distributions following the above design changes shown in the Drawings 01B and 02B are summarised in Table 3 below. These revised flow distributions are for the same total concentrated source flows of 6,000 m3/hr and 7,000 m3/hr for LTR2/HTR and LTR1 concentrated sources respectively.

It can been seen from Table 3 that the revised designs for each line result in modelled extraction flow distributions, which better match the target design flows specified for LTR2/HT2 and LTR1 concentrated sources.

Some of the existing and new ducts with each concentrated source system have dampers recommended as shown in Drawings 01B and 02B. These are specified for specific ducts where the design flow is expected to be exceeded unless dampers are used.

RPC Comment: Comments noted.

Section 5.3.1 Building Air to Biofilter

The current distribution of the total building air extraction flow is heavily biased towards the LTR2/HTR rendering building. The LTR1 building, the LTR2 dryer/meal processing area, and LTR2/HTR raw material rooms would receive a relatively low rate air ventilation under the current design of the building air extraction duct. Proposed changes to the existing system that are highlighted in Table 4 and shown in Drawing 03B are summarised as follows:

shutting off a number of roof line building air vents above the LTR2 wet rendering area; including a new section of LTR2 manifold that allows for extraction of building air above the

LTR2 dryer; blank off several large diameter building air inlets into the LTR2 air manifold; extend the 1500 mm main central manifold so it connects to the main LTR1 building air manifold; increase the size of the LTR1 building air manifold to 1000 mm diameter; modifying the existing LTR1 raw material reception room manifold to extend down to and directly

connect to the LTR1 raw material bin; install new duct connections between the existing LTR2 cold sources manifold and the LTR2 raw

material bins; and10


enclosure of LTR1 and LTR2/HTR raw material bins with closable lids.

RPC Comment: I have no issue with related changes as proposed. In respect to extending ducting to proposed raw material bin lids, see my various comments above including in Section 4.3.1.

Section 5.3.2 Building Air to Atmosphere

Refine the design in terms of heat loadings and required flows to enable additional building air ventilation to atmosphere via vertical stacks (or a common stack) from the following:

LTR1 and LTR2/HTR rendering halls, and LTR2 Dryer/Meal rooms (max. ~ 8 m3/s); and Allow for ventilation of raw material building air into rendering halls (max. ~ 2 m3/s to 4 m3/s).

We estimate total ventilation flows to atmosphere within the range of 30,000 m3/hr to 100,000 m3/hr (in addition the flows extracted to the building air biofilter) to provide a suitable ambient environment for rendering plant staff. It is recommended these flow estimates are refined/checked based on any existing plant temperature records, and estimated heat loads in each plant.

RPC Comment: Conformation of rates of suggested ventilation noted. Also see Sections 3.3.3 and 3.3.4 above. While it is appropriate to comply with employee health and safety indoor air temperature requirements, I expect that all reasonably practicable measures will be implemented to minimise heat ingress into the working environment. Reference has been made to this at various times in s92 requests for information including ensuring all significant heat emitting plant is appropriately thermally insulated (with insulation that can be regularly washed-down). Would Golder confirm whether or not hot processing plant is appropriately thermally insulated (and if so, to what standard) and if not when will this be fully achieved?

The use of sequential building air ventilation to more effectively utilise building ventilation air, which was raised in s92 requests for additional information and which were ignored, has barely rated a mention in this Report. Reference was limited to the comment “However, environmental cooling air required for the rendering halls could be sourced from these [the raw materials reception] rooms.”4 Would Golder provide a more detailed analysis of how building ventilation air flow including additional air for cooling purposes as necessary could be optimised?

Section 5.4.1 LTR1 Concentrated Source Biofilter

It recommended that the current small concentrated source biofilter is dedicated to treating all of LTR1 concentrated sources and continued treatment of NCGs from the WHE plants. This will require pre-cooling equipment for LTR1’s concentrated sources. The options available include the horizontal shell & tube heat exchanger (HX). This was originally dedicated to LTR1 rendering line for cooling and is currently part of the WHE NCG cooling system which also includes a vertical HX.

RPC Comment: I support the recommendation that the current small concentrated source biofilter is dedicated to treating all of LTR1 concentrated sources and continued treatment of NCGs from the WHE plants – except I prefer that a dedicated biofilter is constructed to accept LTR2 and HTR concentrated sources.

Section 5.4.2: LTR2/HTR Concentrated Sources Biofilter (Proposed)

A dedicated biofilter for the cooled concentrated sources from the LTR2 and HTR lines (including HTR cooker NCGs) has a recommended design flow of 9,000 m3/hr (see Table 8). This requires 260 m3 of media to achieve the design loading of 35 m3air/hr per m3media. This indicates a bed area ranging from 200 to 300 m2 depending on the media depth, which will be influenced by the type and location of bed.

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The options for providing a new concentrated sources bed include modifying the existing large building air biofilter or else construction a new bed on site.

RPC Comment: I support the construction of a new (above ground) biofilter dedicated to cooled concentrated sources from the LTR2 and HTR lines (including HTR cooker NCGs). This biofilter should have a design load not exceeding 35 m3air/hr per m3 media if soil is incorporated in the bark media. I reject the possible alternative of modifying the building air ventilation biofilter to provide an integral treatment cell for these non-condensable gases.


Golder recommends the current practice of co-treatment of building and concentrated source air streams be discontinued. A design air loading rate of 50 m3 air/hr per m3media is recommended for the bed, which matches the 100,000 m3/hr design building air extraction flowrate, although operational experience may demonstrate higher loading rates are feasible in terms of treatment performance and bed stability. For such a large bed, the management of bed moisture and avoidance of air channelling will become increasingly difficult at high loadings.

RPC Comment: I support the proposal to discontinue the current practice of co-treatment of building and concentrated source air streams. I also recommend the air loading rate of the building air biofilter be at least 50 m3 air/hour per m3media. If the media of the biofilter consists only of screened good quality Pinus radiata bark nuggets (no soil) then the loading be increased to at least 70 m3 air/hour per m3media to provide for treating more building extraction air. To ensure appropriate bed moisture especially during dry weather conditions I recommend a purpose-designed inlet air duct humidifier be installed.

6.1 Monitoring Instrumentation - Recommendations

Recommended monitoring methods, frequency and logging requirements are detailed in the following Tables for each component of the overall air extraction and treatment system.

Table 9 - LTR1 and LTR2/HTR concentrated sources; Table 10 - Building air extraction syste to biofilter; Table 11 - Building air extraction to atmosphere; and Table 12 - Biofilters.

RPC Comments: Table 9 – For the CSES duct connections to process items, determining pressure differential with a hand-held gauge on a monthly basis may not be sufficiently frequent. I recommend frequency of monitoring be no less than monthly and the actual rate of monitoring be determined from experience with the upgraded systems and the Management Plan then be revised accordingly. I am very supportive for the main CSES Manifolds of the proposed instrumental gauge continuous measurement and logging of pressure, vacuum, and temperature.

Table 10 – I agree with all proposed values.

Table 11 – (building air discharge to atmosphere) Withhold comment at this stage subject to receipt of further information as indicated in the body of this response

Table 12 –Concentrated sources biofilter inlet flow assessment by pitoting frequency for routine monitoring change annual to 6-monthly; pH change 3-monthly to 6 monthly (biofilters subject to rainwash change in pH values is quite slow).

Section 6.1.2 Instrumental Protection


The monitoring system proposed in the above tables specifies a number of locations for continuous real-time temperature, humidity, pressure and vacuum measurement and subsequent data logging. For most locations the instrumentation will need protection from dust, fat, moisture, vibration and heat that is synonymous with rendering process streams. This is an aspect of the overall design that requires further consideration, suffice to say that the for pressure and vacuum measuring equipment, the use of pigtail siphon u-tubes is recommended to protect vacuum and pressure gauges against overheating and fouling. The pigtail would be connected to the duct and its siphon filled with a stable fluid, which protects the instrument.

RPC Comment: I agree these comments.

Section 6.1.3 Instrument Checks & Servicing

The site’s R&M programme should cover the routine checks and servicing of key real time instruments.

RPC Comment: I agree with this.

Section 7.0 Discussion

The report contains Golder’s recommendations for optimising the odour extraction and treatment systems at the site. It is apparent that following a number of process changes the system has been progressively modified since first installed and commissioned.

The modelling of flow distributions within the existing building air and concentrated source systems has made it clear that the existing ducting required modifications to provide a more balanced system, and in particular the isolation of LTR1 from the LTR2 concentrated source system is an important step. The main manifold structure for all extraction systems can be utilised following modifications to provide effective and even flow distributions associated with plant that is targeted by the CSESs.

The existing building air system is in most need of modification to enable adequate flows to be extracted from all process areas and this system requires the more substantive changes to its main manifold to ensure LTR1 building air and cold sources can be extracted effectively. A key change is the direct extraction of raw material bins and have these to include closable lids. Furthermore, the effective containment of air from the large raw material receipt buildings, makes it impractical, nor desirable to try and extract these buildings such that all their air is treated by a biofilter. However there is potential to pull air from these buildings into the rendering halls and so to provide a source of cooling air.

The maintenance of a suitable working environment within the rendering halls and especially the LTR2 dryer room is always a challenge for modern rendering plants. We consider that auxiliary building air ventilation directly to atmosphere is necessary to enable adequate management of the working environment – especially during very warm summer days. However this can be undertaken without causing odour issues given the extent of process emission controls (via the CSESs) and the existing building air -biofilter system.

The biofilter infracture at the site is substantial, however existing cooling system arrangements makes it more practical for LTR1 and LTR2 to be treated via their own dedicated biofilter systems, which provides for less risk and greater flexibility in the operation of these systems long term. To enable this, the construction of an additional concentrated source biofilter is recommended and an above ground system is the preferred option.

Finally, with respect to monitoring of the CSES, BAS and biofilter performances, substantial real-time monitoring and logging of key parameters are recommended (pressure, vacuum, temperature and humidity). This information is sufficient to providing engineering staff and management with early


warnings of gradual loss in the extraction and cooling system performances and especially the build up and gradual block of critical process air extraction ducts.

RPC Comment: Discussion comments noted. These points have been addressed individually.

Section 8.0 Conclusion

Golder concludes by saying that the recommendations in their report will enable TPL to effectively manage the odour effects from their operations to a minor level beyond the site boundary. However, it is also concluded that the changes and strategy recommended in this report are likely to refined and other options be considered following further review and consultation with the Waikato Regional Council, their advisors and TPL engineers.

RCP Comment: Golders conclusion is noted.

Further Points

Existing and Proposed Meal Processing Facilities

RCP Comment: The Golder December 2017 Report discusses processing of meal. It is reported in Section 2.4.2 of that report that while there is no air extraction from the Meal Hall, air is extracted from the meal conveyor and connects to the LTR1 hot sources line. It is also reported that for the proposed new milling facility, a new hammer mill will be installed.

The application for consent included a Building Design Statement that attached draft plans for a new meal hall to improve current site rendering activities. While the Building Design Statement was encouraging, additional technical information was needed to indicate how the target odour capture and control performance will be achieved in practice.

At this stage I am uncertain what the proposed meal milling and conveying ventilation extraction system is. I am also uncertain whether or not meal storage and bagging facilities will also be ventilated as a part of the proposed building air extraction system (and if so, whether it will be ventilated to the biofilter or direct to atmosphere from one of the proposed roof vents).

Could you please advise accordingly. (Note: It is likely Golder has provided additional information current as at mid-2019 in a letter dated 16 July 2019 to Tuakau Proteins Limited and sent to Waikato Regional Council by Mitchell Daysh Limited with their letter dated 2 August 2019, but I cannot find the Golder letter.

Provision of Contingency Measures

RCP Comment: Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions dated 24 April 2020 states as follows: “Effective contingency measures need to be undertaken if objectionable odour occurs. The measures are to be capable of reducing the discharge of odour to such a degree that no further objectionable odour occurs. The contingency measures identified shall include both effective and immediate and long-term solutions. Immediate in this context is agreed to mean within hours, and long term is to allow for upgrades that can take several months or longer.”

As I see it, the Golder Upgrade Report is light on upgrading of contingency measures in the context of Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions. Certainly, there is considerable emphasis on optimising rendering process concentrated sources systems and also optimising building air ventilation system effectiveness. There is also the proposal to install a second concentrated sources biofilter to enable the concentrated sources extraction systems for these rendering plants to be split which will also provide some processing redundancy. No mention was made in respect to retaining


the proposed second large biofilter to assist treating building ventilation air. There is the possibility of increasing the loading rate of the present large biofilter to enable a higher rate of building ventilation air to be treated. However, any practical increase in biofilter capacity would be unlikely to enable building ventilation air control to be an effective contingency measure if malfunction of the concentrated sources system occurred especially if raw materials of marginal to poor quality were being processed. (In addition, provision to provide cooling air to meet health and safety requirements, which was raised by Golder in March 2020, adds significantly to the required rate of building ventilation.) To compensate, Golder has now proposed a partial Split System5 with a high efficiency concentrated sources system for point source odour control with dispersion of part of the building ventilation air through vertical roof-mounted and fan-powered discharge stacks to supplement partial building extraction to biofiltration.

At this stage I believe Golder has not provided sufficient information to fully support their proposal, including the need to fully examine measures to optimise building air ventilation, and the environmental impact of discharging building air to atmosphere as part of the contingency measure if significant issues occurred with the concentrated sources ventilation system.

Consequently, at this stage, complete rendering buildings ventilation air extraction to a suitable biofilter is not a practicable contingency measure based on the information provided by Golder, and the partial system they propose needs further information to be supportable.

DRAFT 1: Dated RCP Review of Golder Report Upgrade of Odour Extraction and Treatment Systems for Tuakau Proteins Limited Received 28 July 2020 – DRAFT 1 6 August 2020 & Emailed to WRC 9 August 2020

Ron Pilgrim

Draft 1

9 August 2020

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Summary

A significant number of sections in the Golder Upgrade Report relate to simplifying and optimising existing processes and I support any such measures where practicable to do so.

In the absence of measured ducting flow rates and/or to supplement measured ducting flow rates Golder has used at various stages data developed from air flow distribution models. Provision of additional information has been requested about the models referred to including if it or they are privately developed models or commercial models, and in any case comment about model operation and limitations. It is reasonable to say that for all validated models the quality of the output data is very dependent on the quality of the input data including any assumptions made.

In respect to Section 3.3.1, Golder comments that the building air ventilation extraction system became significantly unbalanced (modelling indicated around 75% of total flow would be extracted from the LTR2/HTR building and only 19% of flow would be extracted from the LTR1 building). The reason for this is explained to some degree in Section 7.0 (Discussion) of the Golder Report. At what point ventilation imbalance issues became apparent is not stated but I cannot recall mention being made of this imbalance in Golder Reports that formed a part of the current application for the new air discharge permit. However, irrespective, I support practical measures that will optimise air extraction from all significant buildings. In respect to ventilation of raw materials bins, fitting closeable lids directly connected to the building air ventilation system as targeted extraction should significantly improve

5 Split System- as discussed by Terry Schulz of the Odour Unit Pty Limited, Mascot, NSW 2020.15


extraction efficiency. This is providing such lids can be appropriately constructed to resist damage when moved to allow off-loading from trucks. In addition, their effectiveness when trucks are off-loading raw materials will also be compromised unless a relatively sophisticated design is developed.

In respect to Section 3.3.3 (additional building ventilation), Golder advises modelling results indicate that the two rendering halls and the LTR2 dryer/meal processing room (three process areas) may need additional ventilation for working environment management (cooling) within the range of 30,000 m3/hour to 100,000 m3/hour in additional the 90,000 m3/hour of building air that could be ventilated to the building air biofilter (which will also receive 10,000 m3/hour of air from the raw material reception halls ex the their bins). Consequently, the need for additional ventilation air is currently uncertain, and in addition, the rate of additional air flow is also uncertain. While it is entirely appropriate to comply with health and safety indoor air temperature requirements, I expect all reasonably practicable measures will be implemented to minimise heat ingress into the working environment. Reference has been made to this at various times in requests for additional information including ensuring all significant heat emitting plant is appropriately thermally insulated. Golder is requested to confirm whether or not hot processing plant is appropriately thermally insulated (and if so, to what standard) and if not when will this be fully achieved and what difference will this make to estimated building airflows.

The use of sequential building air ventilation to more effectively utilise extraction air, which was raised in requests for additional information and which were ignored, has rated barely a mention in this Report. Reference was limited to the comment “However, environmental cooling air required for the rendering halls could be sourced from these [the raw materials reception] rooms.”6 Golder is requested to provide a more detailed analysis of how building ventilation air flow including additional air for cooling purposes as necessary could be optimised.

In Section 3.3.4 (odour impact from building air ventilation) Golder comments about the evaluation using atmospheric dispersion modelling of ventilating rendering buildings in part through three 3m high vents located on building roofs. This discharge would be associated with indoor residual odour associated with fugitive emissions which escape the concentrated sources systems and from diffuse sources. While the indicative odour modelling suggests little issue downwind at the nearest sensitive receiver, the rate of odour emission of 16,000 OU/s from the roof vents in total is quite low and more supporting information is required including how the assumed 16,000 OU/s discharge rate was derived. (Modelling information to be provided should be of the quality expected for an application to WRC for a new air discharge permit.) I doubt the indicated rate of odour emission would be consistent with fugitive emissions into the factory building(s) if significant issues with the concentrated sources system occurred, especially if the quality of raw materials being processed at the time was marginal or poor. While I appreciate increasing the rate of ventilation of the buildings by 43,000 Am3/hour would greatly assist providing an improved working environment especially during warm weather, more information should be provided as requested above. This includes the use of sequential building air ventilation to more effectively utilise extraction air (for example, Golder’s suggestion that environmental cooling air for the rendering halls could be sourced from these the raw materials reception rooms).

Golder states the required outcome of the design of the CSES and dryer NCG extraction system is to enable the routine discharge of rendering building air to atmosphere as necessary to achieve a safe working environment while not causing more than minor levels of rendering odours (defined as a maximum predicted 99.5 percentile 1-hour concentration 2 OU/m3) at the site boundaries due to building air discharge. I have expressed reservations in Section 3.3.4 above about this design outcome. These comments relate to the discharge of building ventilation air direct to atmosphere, providing more information in respect to further minimising heat emissions into the working environment, and adopting sequential air ventilation to more effectively utilise building ventilation air (including environmental

6 Page 5 of Report.16


cooling air for the rendering halls could be sourced from raw materials reception rooms). I also have reservations about the appropriate ambient air odour guide line and percentile, and in any case it should apply to all sensitive development outside of the Company’s premises, not just to the “nearest private house”.

It is important to keep in mind that TPL abuts sensitive development, and at least some of the occupiers of which have experienced significant odour nuisance over some years and are sensitised.

My preference is that the LTR1 and LTR2/HTR concentrated source systems return to isolated systems. This includes removing of the concentrated sources extraction air associated with LTR2/HTR from the Building Air Biofilter and routed to an additional concentrated sources biofilter. Issues with the building air biofilter media drying out especially at higher air loading rates should be solved by installing a purpose-designed humidifier in the inlet duct of this biofilter.

In respect to existing and proposed meal processing facilities, Section 2.4.2 Golder’s December 2017 Report stated that while there is no air extraction from the Meal Hall, air is extracted from the meal conveyor and connects to the LTR1 hot sources line. It is also reported that for the proposed new milling facility, a new hammer mill will be installed. The application for consent included a Building Design Statement that attached draft plans for a new meal hall to improve current site rendering activities. While the Building Design Statement was encouraging, additional technical information was needed to indicate how the target odour capture and control performance will be achieved in practice. At this stage I am uncertain what the proposed meal milling and conveying ventilation extraction system is. I am also uncertain whether or not meal storage and bagging facilities will also be ventilated as a part of the proposed building air extraction system (and if so, whether it will be ventilated to the biofilter or direct to atmosphere from one of the proposed roof vents).

Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions dated 24 April 2020 states that effective contingency measures need to be undertaken if objectionable odour occurs, and the measures must be capable of reducing the discharge of odour to such a degree that no further objectionable odour occurs. The Golder Report is light on discussing contingency measures in the context of Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions. There is considerable emphasis on optimising rendering processes and their concentrated sources extraction systems and building air ventilation system effectiveness. What specifically concerns Waikato Regional Council is there are no recommended or possible options that TPL could implement while future upgrades are being implemented, and after commissioning if objectionable odour still persists. For example, one possibility may be to cease operation of the Tuakau Plant until at least critical remedial work is carried out; and another possibility could be to reduce the processing capacity of the overall plant sufficiently to enable effective operation of part of the plant while remedial work is being carried out on the remaining part of the plant. There may well be other contingency options available to TPL and if so these, and the possible examples above, should be explored and discussed.

Conclusion

A significant number of sections in the Golder Upgrade Report relate to simplifying and optimising existing processes and these are supported where practicable to implement.

In the absence of measured ducting flow rates and/or to supplement measured ducting flow rates Golder has used at various stages data developed from air flow distribution model(s). Provision of additional information has been requested about these models.

In respect to Section 3.3.1, Golder comments that the building air ventilation extraction system has became significantly unbalanced (modelling indicated around 75% of total flow would be extracted from the LTR2/HTR building and only 19% of flow would be extracted from the LTR1 building). The reason


for this is explained to some degree in Section 7.0 (Discussion) of the Golder Report. I support practical measures that will optimise air extraction from all significant buildings.

Golder advises based on flow modelling results from the two rendering halls and the LTR2 dryer/meal processing room (three process areas) may need additional ventilation for working environment management (cooling). However, the need for extra ventilation air is not certain, and if needed, the rate of additional air flow is also uncertain. In addition, as far as practicable measures to minimise heat ingress into the working environment should be implemented using thermal insulation for example, and adoption of sequential building air treatment – a more detailed analysis of which has been requested from Golder.

While indicative odour dispersion modelling of the proposal to discharge part of the building ventilation air from three rooftop vents suggests little issue downwind at the nearest sensitive receiver, the rate of odour emission of 16,000 OU/s from the roof vents in total is quite low. More supporting information is required including how the assumed 16,000 OU/s discharge rate was derived. (Modelling information to be provided should be of the quality expected for an application to WRC for a new air discharge permit.) While I appreciate increasing the rate of ventilation of the buildings by up to 43,000 Am3/hour would greatly assist improving the working environment especially during warm weather, more information is requested. This includes the use of sequential building air ventilation to more effectively utilise ventilation air such as the suggestion that environmental cooling air for the rendering halls could be sourced from the cooler raw materials reception rooms. I also have reservations about the appropriate ambient air odour guide line and percentile level suggested, and that it should apply to all sensitive development outside of the Company’s premises, not just to the “nearest private house”. It is important to keep in mind that TPL abuts sensitive development, and at least some of the occupiers of which have experienced significant odour nuisance over many years and are sensitised.

The application for consent included a Building Design Statement that attached draft plans for a new meal hall to improve current site rendering activities. However, additional technical information was and still is needed to indicate how the target odour capture and control performance will be achieved in practice.

Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions dated 24 April 2020 requires that effective contingency measures need to be undertaken if objectionable odour occurs, and the measures must be capable of reducing the discharge of odour to such a degree that no further objectionable odour occurs. The Golder Report does not specifically discuss recommended or possible contingency options that TPL could implement to prevent the emission of objectionable odour while upgrades are being implemented, and after commissioning if objectionable odour still persists. Contingency options available to TPL should be explored and discussed.

Taking the Golder Upgrade Report in its entirety, there are a significant number of sections relating to simplifying and optimising existing processes and these are supported where practicable to implement. However, there are still significant matters that require additional information to effectively assess their consequences including provision of effective contingency measures in respect to Section 4(d) of the Guiding Principles for Pre-Hearing Expert Discussions dated 24 April 2020. Consequently, since the Report is incomplete, I am unable to say at this stage that if the overall proposals are fully implemented as indicated in the Golder Report that the emission of objectionable or offensive odour beyond the boundary of the Tuakau Proteins Limited site will be reliably and consistently prevented. My comments in this respect are also reinforced by the second paragraph of the following statement in Section 8 (the concluding statement) of the Golder’s report: “It is concluded that the recommendations in this report will enable TPL to effectively manage the odour effects from their operations to a minor level beyond the site boundary. However, it is also concluded that the changes and strategy recommended in this report are likely to refined and other options be considered following further review and consultation with the Waikato Regional Council, their advisors and TPL engineers.” (Emphasis added.)


----------------------------------------------------------------------

The Peer Review dated 6 August 2020 by Terry Schulz of The Odour Unit of the Golder Associates Upgrade Report was received by the undersigned on 14 August 2020.

This Addendum comprises extracts from the Peer Review.

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Addendum

The report also offers comments and suggestions that indicate that a concept design is being developed, although a clear way forward and recommendations are not included. It reads like an interim report. [Last sentence of Paragraph 5.]

The Golder Report contains an excellent detailed description of the existing TPL plant and its OCS [odour control system]. The process and layout drawings are excellent. It is difficult for me to envisage how any previous considerations about the design and performance of the OCS could have taken place without this information. [Part of Paragraph 6.]

Much of the commentary and improvement concepts appear to have been based on opinion and experience at other rendering plants, rather than actual plant operating data such as airflow measurements, pressure profiles, fan specifications, and perhaps even smoke testing. Reliance is on a computer-based airflow distribution modelling to determine individual airflows through the existing OCS without verifying the accuracy of these important projected results by actual field measurements. The report cites many assumptions required by this model without discussion of accuracy or confidence. Actual plant airflow data within the Concentrated Source Extraction System (CSES) or to the existing biofilters is fundamental to the development of an effective and optimised upgrade to the OCS. This data will be required as part of the detailed design of new extraction ductwork and biofilter improvements. [Part of Paragraph 7.]

Notwithstanding the above comments, I am confident that the improvements to the extraction system identified in the assessment will result in a substantial decrease in concentrated-source process odour releases into the rendering buildings and a corresponding decrease in fugitive odour emissions from the buildings. It is difficult to say whether these improvements will be sufficient to ‘eliminate objectionable odour’ at the nearest receptor locations. [Paragraph 8.]

Overall, the proposed changes to the CSES network are likely to substantially improve process odour capture. However, it is recommended that direct airflows within the major branches of the CSES in all three plants and to each of the biofilters be measured as a priority, to add confidence to the changes proposed. [Paragraph 11.]

As a final comment, I agree with the report that the BAS (Building Air System) airstream will not be saturated. In my experience, it will be a few percentage points above the ambient relative humidity (RH). This air will not be compatible with sustainable good odour removal performance in biofilters, without humidification. [Paragraph 14.[

Notwithstanding the above considerations and accepting the sensitivity of the community, I believe that more work is needed to justify the implementation and use of a direct-to-atmosphere ventilation system. I believe this concept should be deferred until such times as the effectiveness of any future upgrade to the OCS at the TPL plant can be demonstrated. [Paragraph 19.]

In my experience, it is very difficult to adequately flow balance a dual ventilation/CSES system, using only one fan. This is due to much lower pressure losses in the simpler ventilation duct system than in the more complex, higher pressure-loss CSES ductwork. Dampers are required. It is unclear whether the air distribution modelling examined this issue or included a flow damper in the main ventilation duct. My


company, in similar rendering plant biofilter systems, has always used separate fans for ventilation and CSES airflows. [Part of Paragraph 21.]

I am concerned that the report contains no pressure data at all, other than the suggestion of a 4 kPa duty on this fan and references to adequate negative pressures at the collection points. Pressure data is relatively easy to collect and is very informative. Any further analysis should also consider changes in biofilter back pressure with bed moisture level. It is known that the existing ‘pipe-in-gravel’ biofilter design typically incurs relatively high pressures and is more pressure-sensitive to bed moisture levels and adequate drainage than plenum floor biofilters. Changes in fan airflow are therefore likely. [Part of Paragraph 22.]

While I accept that the biofilter design is widely used in New Zealand, my own experience with similar designs in Australia is that large ‘pipe-in-gravel’ biofilters often suffer from ‘patchy’ odour removal performance, despite very low loading rates. This is due mainly to difficulties in achieving and maintaining adequate and even bed moisture levels across quite large areas. I have also found that the shallow bed depth makes this type of biofilter susceptible to short-circuiting and that blockages in the air distribution openings can occur. [Part of Paragraph 24.]

Having made this point, I am ambivalent about the continued use of the existing biofilters and how they are configured or loaded, provided that evidence can be tabled showing sustainable good odour-removal performance across a range of operating and weather conditions. However, it is vital that all airstreams directed to the biofilters be fully humidified prior to treatment. This typically involves a dedicated scrubber/humidifier vessel or a series of in-duct water spray nozzles. For the biofilter design in use at the TPL plant, unevaporated carry-over water from an in-duct spray system may present problems with drainage and blockages. [Paragraph 25.]

All but the smallest of biofilter systems designed by my company in the past 20 years have been equipped with humidification systems. In my opinion, it is the single largest factor in achieving good sustainable performance. I note that Golders have previously stated expressly that no humidification is proposed for BAS Biofilter 1, despite acknowledging (Section 4.4.2 of the Golder Report) that the BAS Biofilter is more prone to drying out and air channelling than the CSES Biofilter 2, which receives fully saturated air. [Paragraph 27.]

While I have already mentioned my preference for combining CSES and Ventilation airflows prior to biofilter treatment, this is conditional on pre-humidification of the air. [Paragraph 28.]

In my experience, humidified biofilters are not sensitive to higher odour concentration/loadings if the inlet odour concentration is less than 50,000 ou – a figure most unlikely to be encountered in a mixed ventilation/CSES airstream. [Paragraph 29.]

Should the existing biofilters continue to be used, I recommend that an intensive condition and performance review be undertaken. This would include total airflow, pressures, temperatures, spatial outflow distribution (i.e. the evenness of the air airflow across the bed), odour testing, and physical examination of the pipe distribution and drainage systems. The assessment should ideally cover wet and dry weather conditions. [Paragraph 30.]

As a final biofilter-related comment I am disappointed that the Golder Report does not consider the replacement of both biofilters with a single high-rate unit, based on an above-ground, plenum floor, deep bed (2 metres), low-pressure design, loaded at 100 m3/m3/hr and equipped with a single humidifier/scrubber unit. This equates to a biofilter bed area of 750 m2 for an airflow of 150,000 m3/hr. [Paragraph 31.]


The Golder Report sets out an extensive process and OCS monitoring program that reflects the need for regular checks on condition and performance throughout the system. I strongly agree with the general approach of key parameter monitoring. [Paragraph 32.]

Concluding Comments The Golder Report documents previously lacking technical information which clearly lays out the existing processing plant and OCS. This has enabled a mostly desk-top analysis to be carried out which has identified shortcomings in the existing CSES and BAS and has proposed concepts for improvements to both systems. [Paragraph 36.]

The extent to which these concepts can be further developed is hampered by the lack of physical operation and performance data, as well as equipment specifications from the TPL plant. Currently, the Golder Report infers recommendations but appears to lack sufficient engineering rigour, and perhaps the confidence needed, to nominate a clear way forward. [Paragraph 37.]

My recommendation is to gather the above important physical data and specifications and combine this with the knowledge documented in the Golder Report, such that a genuine Concept Design for an upgraded OCS can be developed. [Paragraph 38.]

Ron Pilgrim Consulting Comments

In paragraph 8 Terry Schulz, notwithstanding some previous comments, expresses confidence that the improvements to the extraction system identified in the Golder assessment will result in a substantial decrease in concentrated source process odour releases into the rendering buildings and a corresponding decrease in fugitive odour emissions from the buildings. However, then comments that “It is difficult to say whether these improvements will be sufficient to ‘eliminate objectionable odour’ at the nearest receptor locations”.[emphasis added.]

In paragraph 19, Terry states that “…notwithstanding the above considerations and accepting the sensitivity of the community, I believe that more work is needed to justify the implementation and use of a direct-to-atmosphere ventilation system. I believe this concept should be deferred until such times as the effectiveness of any future upgrade to the OCS at the TPL plant can be demonstrated.” [Emphasis added.] [Paragraph 19.]

In paragraphs 22 to 29 inclusive, Terry discusses the existing biofilters. He notes they are relatively unsophisticated and more pressure-sensitive to bed moisture levels and adequate drainage than are plenum floor biofilters. The large ‘pipe-in-gravel’ biofilters often suffer from ‘patchy’ odour removal performance despite very low loading rates and this is due mainly to difficulties in achieving and maintaining adequate and even bed moisture levels across quite large areas. In addition, he has found that the shallow bed depth makes this type of biofilter susceptible to short-circuiting and also blockages in the air distribution openings can occur. Having said this he is ambivalent about the continued use of the existing biofilters and how they are configured or loaded, providing that evidence can be tabled showing sustainable good odour-removal performance across a range of operating and weather conditions. He cautions, however, it is vital that all airstreams directed to the biofilters be fully humidified using a dedicated humidifier or a series of in-duct water spray nozzles, but also cautions that un-evaporated carry-over water from an in-duct spray system may present problems with drainage and blockages. Terry also stated his preference for combining CSES and building ventilation airflows prior to biofilter treatment because humidified biofilters are not sensitive to higher odour concentration/loadings if the inlet odour concentration is less than 50,000 ou – a figure most unlikely to be encountered in a mixed ventilation/CSES airstream.

In paragraphs 30 and 31, Terry recommends that if the existing biofilters continue to be used, an intensive condition and performance review be undertaken with the assessment covering wet and dry weather


conditions. Terry also expresses his disappointed that the Golder Report does not consider the replacement of both biofilters with a single high-rate unit, based on an above-ground, plenum floor, deep bed (2 metres), low-pressure design, loaded at 100 m3/m3/hr and equipped with a single humidifier/scrubber unit. This equates to a biofilter bed area of 750 m2 for an airflow of 150,000 m3/hour.

In his conclusions, Terry comments that the extent to which concepts can be further developed is hampered by the lack of physical operation and performance data, as well as equipment specifications from the TPL plant. Currently, the Golder Report infers recommendations but appears to lack sufficient engineering rigour, and perhaps the confidence needed, to nominate a clear way forward. He recommends the important physical data and specifications be gathered and combine this with the knowledge documented in the Golder Report, such that a genuine Concept Design for an upgraded OCS can be developed.

I noted that the only reference to increasing building ventilation airflows to provide a cooler working environment was in paragraph 16 where Terry commented that “…a case is put for the direct ventilation of air in the LTR2/HTR and LTR1 rendering halls to atmosphere, based on the need for cooling and operator comfort.” I believe that acceptance of using ventilation air for cooling of internal working areas is based on standard Australian practice of substantially increasing building ventilation rates in hot climates to comply with Health and Safety Requirements. Presumably, the Australian practice also includes ensuring hot plant is appropriately thermally insulated.

Terry made no mention in his report about the desirability of optimising building ventilation rates by sequential ventilation although my understanding of his response when asked during the meeting was to the effect that this goes without saying.

Terry also made no comments in his report about maintaining the integrity of building wall and roof cladding.

In respect to high rate biofiltration unit referred to by Terry in his paragraph 31, I understand the odour filtration media consists of screened bark nuggets and does not contain soil or other added fines.

Ron Pilgrim

21 August 2020


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