Evidence of Mr Alan Wolski
192 Mr Wolski gave evidence in an affidavit dated 17 December 2019. In his affidavit Mr Wolski deposed that he was a registered professional engineer in Queensland, and an employee of GHD as a Technical Director (Structures). He deposed that he had 34 years' experience in the design development and procurement of government building infrastructure, and further that as a senior and Principal Structural Engineer in the Queensland Department of Works for 24 years he conducted and supervised maintenance inspections of damaged buildings.
193 He also deposed that his work as a forensic engineer had included investigations of concrete decay, floor strengthening, building systems review and review of underpinning systems.
194 Materially Mr Wolski deposed:
6. On 14 December 2017, GHD delivered a Reservoir Condition Assessment Alexandra Hills High Level Reservoir (Condition Assessment). Annexed hereto and marked "AW-1" is a copy of that Condition Assessment.
7. On 14 February 2018, GHD delivered a Preliminary Report on the Implications of Proposed Antenna Installations at Alexandra Hills High Level Reservoir (Preliminary Report). Annexed hereto and marked "AW-2" is a copy of this Preliminary Report.
8. On 1 November 2018, GHD delivered a Memorandum to Seqwater titled "Alexandra Hills Reservoir Roof Condition" (1 November 2018 Memorandum). Annexed hereto and marked "AW-3" is a copy of the 2 November 2018 Memorandum.
9. On 16 November 2018, GHD drafted a Reservoir Condition Assessment Addendum to GHD Memorandum dated 14 February 2018 - Correction and Update dated 16 November 2018 (Addendum Report). Annexed hereto and marked "AW-4" is a copy of the Addendum Report.
10. On 26 November 2018, GHD was briefed with a letter of instructions by the Respondent's solicitors, K&L Gates, to answer a number of questions regarding the Reservoir Tower. Annexed hereto and marked "AW-5" is a copy of the letter of instructions.
11. On 8 March 2019, I, along with Mr Daniel Anstice of GHD, prepared a report regarding the roof slab of the Alexandra Hills Reservoir Tower (8 March 2019 Report). Annexed hereto and marked "AW-6" is a copy of the 8 March 2019 Report.
12. I have read and reviewed the report of Mr Antony Vose dated 1 October 2019, filed by the Applicant.
13. On 28 October 2019, I prepared a Memorandum containing my response to Mr Vose's report (28 October 2019 Response). Annexed hereto and marked "AW-7" is a copy of the 28 October 2019 Response.
14. On 22 November 2019, I prepared a further Memorandum containing my further response to matters raised in my 28 October 2019 Response (22 November 2019 Response). Annexed hereto and marked "AW-8" is a copy of the 22 November 2019 Response and letter of instructions.
195 The Preliminary Report dated 14 February 2018 stated, in summary:
2 Findings
The following points summarise GHD's findings with relevance to the suitability of the proposed future antenna installations at the Alexandra Hills High Level Reservoir:
2.1 Resilience Capacity
• Security of site access, in relation to telecommunication maintenance staff accessing the reservoir, has implications for resilience of the reservoir, in terms of ensuring an appropriate water supply.
2.2 Structural Capacity
• Calculations will be conducted on the structural capacity of the reservoir, as well as the structural impact of the installed telecommunication equipment. The structural capacity of the reservoir is deemed likely to be sufficient to support the installed telecommunications as well as future installations.
2.3 Electrical Capacity Assessment
• The assessment on electrical capacity has been carried out to determine the electrical loading imposed on Seqwater from the telecommunication installations and associated equipment. The assessment concluded that the current electrical capacity is sufficient to operate and maintain the reservoir, and that Seqwater are able to meet the maximum current capacity requirement. However, clearly this assessment would need revisiting in the light of any planned future telecommunications installations and appropriate information must be provided by the telecommunications providers for potential installations in order that such an assessment can be conducted. Likewise, the electrical capacity assessment (and the implications of current and future telecommunications installations) would need revisiting upon any future upgrade/expansion works required by Seqwater, with respect to ensuring the safe operation and maintenance of the reservoir in the future.
• It would be prudent for future telecommunications installations applications to consider utilising an independent mains supply.
• The communications carrier facilities built into the water tower stair well area, and indeed the proposed Satellite wall mounted communication cabinet (Land Access and Activity Notice, dated 2 May 2017), may provide some added risk to the safe operation of the water tower. The risks associated with the carrier communications equipment and associated batteries being located in the tower is that if there is any fire event that occurs while the tower is occupied with personnel above the communications equipment levels, the personnel's only viable escape path would be compromised by smoke.
2.4 Whole of Life Management
2.4.1 Residual Life of Structure
• Given its age, the high level reservoir structure itself would likely have been designed for a service life of 50 years +/- 10 years, i.e. 40 to 60 years. The ability of the reservoir to function beyond the maximum design life cannot be predicted at this time.
2.4.2 Future Operation and Maintenance Activities
Risk of Radio Frequency (RF) Exposure
• The presence of telecommunication equipment at the reservoir introduces a risk of Radio Frequency (RF) exposure to workers in accessing the roof and the tank surrounds. Therefore, all personnel accessing these zones (including Seqwater staff carrying out routine inspection and maintenance) must have undergone RF awareness training, which is considered additional to the training normally required to access and enter a Seqwater reservoir. A preliminary review of the report by CoreEarth titled "Alexandra Hill Water Supply Reservoir - RF EME Measurement Survey for Seqwater", dated 5th October 2017, indicates that there are no issues accessing the reservoir by the external ladder or by entering the reservoir hatch. However, there is an exclusion zone approximately 1.75 m directly above the ladder, of which workers must be made aware. Due to the arrangement of the telecommunication equipment pointing outward from the reservoir, and the directional nature of RF emittance, there is a significant hazard when approaching the reservoir from outside its footprint, e.g. in an EWP delivering equipment. Any proposed works that involve approaching the reservoir from the outside must be detailed in a Safe Work Method Statement and an approach plan, detailing the proposed method of safe approach (likely to involve significant logistics, an outage, making future inspection, operation and maintenance problematic) and access.
Health and Safety Issues Associated with Inspection and Maintenance
• As mentioned above, the risks associated with the carrier communications equipment and associated batteries being located in the tower is that if there is any fire event that occurs while the tower is occupied with personnel above the communications equipment levels, the personnel's only viable escape path would be compromised by smoke.
• As also mentioned above, due to the arrangement of the telecommunication equipment pointing outward from the reservoir, and the directional nature of RF emittance, there is a significant hazard when approaching the reservoir from outside its footprint whilst the antennae are switched on (see Figure 1 below). Considerable effort is required to switch off all antennae, thus already making routine inspection, operation and maintenance of the reservoir extremely difficult.
• The handrail is unfit for its purpose, which is to act as a safety rail for workers on the roof. A number of telecommunications equipment were noted to be affixed to the handrail. Any use of the handrail besides its primary purpose is not appropriate, as it impedes access to the handrail in an emergency situation. Therefore, it is recommended that all existing installations affixed to the handrail are removed and that no future installations are affixed to the handrail. Additionally, the very poor condition of the handrail means that the current telecommunication equipment attachments are not structurally sound. This poses a considerable safety risk, both for workers on the roof and those below. The handrail and bolts should be replaced at the earliest opportunity.
• The proposed Location A (see Proposed Antenna No. 17 on Figure 2 below) of a future telecommunications installation is not appropriate with regards to its proximity to the access hatch, as a sufficient clear zone is required around the hatch. A minimum clear distance of 2000 mm is required where a fall hazard exists at an entry point. In addition, sufficient clear distance is required in order to set up tripods and safely lay down and pick-up personnel and materials required for inspection and maintenance within the reservoir.
• Insect nests and bird's droppings were also noted throughout the internal tower. While these are located in the reservoir and therefore do not affect water quality, they could pose a health risk for workers within the tower and should be removed.
• The vent at the centre of the reservoir roof is made from asbestos cement, thus access to the roof area should be strictly controlled until removal of the asbestos is complete.
196 The report then set out maintenance activities required to address defects (including removal and replacement of the handrail on the roof and removal of antennae attached to the handrail), although noting that fire risk, asbestos and RF exposure issues outlined created difficulties in carrying out those defects.
197 The report concluded:
3 Summary
In summary, any future installations will increase the risk associated with resilience and current health and safety issues due to increasing both the number of people accessing the reservoir and the number of antennae installed on the reservoir.
It is recommended that all existing installations affixed to the handrail are removed and that no future installations are affixed to the handrail.
The electrical capacity assessment would need revisiting in the light of any planned future telecommunications installations and appropriate information must be provided by the telecommunications providers for potential installations in order that such an assessment can be conducted. Likewise, the electrical capacity assessment (and the implications of current and future telecommunications installations) would need revisiting upon any future upgrade works required by Seqwater, with respect to ensuring the safe operation and maintenance of the reservoir in the future. It is therefore recommended that future telecommunications installations applications consider utilising an independent mains supply.
The proposed antenna Location A is not appropriate due to its proximity to the access hatch, as a sufficient clear zone is required around the hatch. A minimum clear distance of 2000 mm is required where a fall hazard exists at an entry point, sufficient clear distance is also required to lay down and pickup personnel and materials required for inspection and maintenance within the reservoir.
The current fire risk and potential RF and asbestos exposure issues create difficulties in carrying out many of the maintenance activities required to address current defects. All personnel accessing potential RF exposure zones must have undergone RF awareness training, which is considered additional to the training normally required to access and enter a Seqwater reservoir.
Considerable effort is required to switch off all existing antennae, thus already making routine inspection, operation and maintenance of the reservoir extremely difficult.
Given its age, the high level reservoir structure itself would likely have been designed for a service life of 50 years+/- 10 years, i.e. 40 to 60 years. The ability of the reservoir to function beyond the maximum design life cannot be predicted at this time.
With respect to the proposed location of equipment (antenna at both locations A and B on roof plus one wall mounted communication cabinet) proposed by Satellite in their Land Access and Activity Notice dated 2 May 2017 (LAAN), these installations are likely to affect Seqwater's operation and maintenance from a safety/operation/maintenance perspective. It is recommended that no further installations be allowed at the Alexandra Hills High Level Reservoir until the electrical safety risks be rectified, the asbestos vent be removed and an operations and maintenance plan is in place which allows regular safe access to both the internal and external faces of the reservoir.
A telecommunications mono-pole is already present at the Alexandra Hills Reservoir site, and presents a viable alternative option for the installation of the proposed telecommunication equipment. An assessment can also be carried out to determine other suitable areas of the site to be made secure for the purpose of installing poles and antennae, as an alternative to installation on the reservoir.
198 Annexure AW-4 to which Mr Wolski referred was a letter from Mr Daniel Anstice to the respondent, as follows:
Dear Carmel,
Reservoir Condition Assessments 16/17
Addendum to GHD Memorandum dated 14th February 2018 - Correction and Update
I am writing this addendum to provide a correction and update to GHD's memorandum entitled 'Preliminary Report on the Implications of the Proposed Antenna Installations at Alexandra Hills High Level Reservoir', dated 14th February 2018.
Under section 2.2 of the memorandum, GHD state the following:
"The structural capacity of the reservoir is deemed likely to be sufficient to support the installed telecommunications as well as future installations."
We have since become aware that the reservoir was designed in accordance with Standards Association Australia (1952) Minimum Design Loads on Buildings - SAA Interim 350. Seqwater believe that the 1955 reprint was the current reprint at the time of the design of this reservoir and was not superseded until the release of AS CA34.1-1969.
Upon consideration of the designed intent, we now remove the above sentence from the memorandum, by way of this addendum letter.
Should you have any queries regarding this letter please contact the undersigned.
199 In the 8 March 2019, Dr Anstice and Mr Wolski opined, inter alia:
3.1 Question - Please provide an explanation as to why GHD removed the following sentence from the Preliminary Report, by way of the Addendum Report: "The structural capacity of the reservoir is deemed likely to be sufficient to support the installed telecommunications as well as future installations"
Answer - The sentence was removed as no structural analysis had taken place, and as such no assertion could be made in relation to the structural capacity.
3.2(c)(i) Question - With respect to installing additional telecommunication equipment, is there any effect on the structural integrity of the Alexandra Hills Reservoir roof?
Answer- With respect to the integrity (durability or structural load carrying capacity) of the roof slab, correctly installed telecommunications equipment, subjected to the professional oversight of the building approval process, will not reduce the structural integrity of the roof slab (the roof slab being supported only by the walls at its extremities).
What can result from permanently installing equipment on the roof slab is a reduction in additional live load that can be supported by the roof slab. This may prejudice the ability of the slab to support maintenance activities by the asset owner. The assessment of the impact of an individual piece of permanent equipment does require professional engineering calculation. In the broader context of construction work, in Queensland this process is managed under the Building Approval system.
Under the the [sic] Qld Building Act, an antenna is specifically listed as a class 10 b Other Structure and is subject to the provisions of those regulations.
The structural impact of installing an individual piece of equipment depends on its weight and location, in particular its juxtaposition to existing equipment on the roof slab. The roof slab has a very low allowable live load, consistent with the design code of the time of its design and broadly consistent with the current design code. To simplify design, these codes assume a uniformly distributed load over the whole roof. While individual telecommunications equipment pieces may be heavier than the allowable load it is not covering the whole roof. In placing the equipment near the edge of the roof slab and not at mid-span, heavier equipment loads can be accepted.
Some of the equipment is near the edge of the roof slab or fixed to the wall, in which case the slab sees no load. From a bending action consideration, the edge of the slab can be taken to mean 600 mm from the physical outer edge. Some of the equipment is located further than 600 mm from the physical outer edge and thus the slab may see some load.
200 Dr Anstice and Mr Wolski gave an opinion concerning installation of telecommunications equipment on the roof, including:
Correctly installed, avoiding the potential issues noted above, fixing equipment to the roof slab would not have any structurally deleterious effect.
201 Dr Anstice and Mr Wolski opined that it would not be appropriate to install telecommunications on a new safety handrail after the handrail replacement, because:
The handrail's only intended purpose was to act as a safety rail for workers on the roof, and any other use could impede access to the handrail in an emergency situation; and
Affixing antennae equipment to handrails could lead to overloading the handrail fixings due to an increased wind load or fatigue.
202 In relation to the impact of the installation of third party telecommunications equipment on the Reservoir Tower roof, they opined:
There was a risk of attachment bolts coming into contact with the reinforcement in the reinforced concrete structure;
Installation of equipment on the roof meant loss of space due to the equipment itself, loss of access to the "RF" zone of that third party telecommunications equipment, and less space for not only the respondent's maintenance personnel and equipment but also heavier equipment;
Because cable trays associated with telecommunications equipment have been affixed around most of the roof, storm water run-off is impeded, leading potentially to ponding and water backflow from the roof into the ventilation penetration.
203 In relation to whether the centre of the roof of the Reservoir Tower had a reduced load bearing capacity, and the area of the reduced loadbearing capacity, Dr Anstice and Mr Wolski opined as follows:
Based on information provided by Seqwater our understanding is that 41 telecommunication items (as per Core Earth Report entitled "Alexandra Hill Water Supply Reservoir R F EME Measurement Survey for Seqwater", dated October 2017) with a total estimated mass of 1074 kg (calculated by GHD with the aid of internet sources) are present at the roof, this works out to an average mass of approximately 25 kg. A reasonable assumption would be that this equipment has a structural zone of influence of a 1 m wide annulus around the perimeter.
The total live load that can be supported by the roof (assuming 41 kg·/ sq·m derived from back calculation from current concrete code) is 1674 kg. In the worst current situation this leaves a remaining allowable live load 600 kg which would be carried over the 5.2 m diameter inner "clear" space. This gives an allowable live load over every sq m on the remaining slab of 27.9 kg/ sq m.
As explained in para 3.2, the useable open area of the residual roof is only 16 sq m. The total load capacity for the roof capacity for the whole roof will not change. This means that on the useable area, 600 / 16 = 37.5 kg/ sq m can be applied.
It must be stressed that this calculation is simply a maximum lower bound estimate. In reality, several of the equipment pieces are mounted on the wall of the tank or right on top of the wall. It would not take much of this load to be taken off the slab to bring the residual allowable live load back up to its design value.
It is equally possible that given the age of the roof, unknown construction quality, and unknown effects of multiple telecommunication equipment installations, the total allowable load on the roof may be less than the design value. The only certain way to determine the load capacity of the roof is to test load it up to close to its theoretical elastic limit and back calculate an allowable capacity from measured strains.
204 In relation to the live load bearing capacity of the Reservoir Tower roof in respect of workers carrying out work on its surface, Dr Anstice and Mr Wolski opined:
The roof is a restricted space by way of its accessibility and authorised access to the site. The roof is not suitable for a crowd load. The implicit assumption in the low design load of 37 kg / sq m (41 kg/ sq m actual load capacity) is that in reality not every square metre will be concurrently loaded. The design standard currently and of its time would not anticipate that more than 5 persons or equivalent equipment load (say 595 kg) would be working on the roof at one time and they would not be bunched together or all standing at mid-span. It is imperative that a Safe Work Method to stop crowd loading be understood by workers on the site.
By way of its extreme age, wherein all manner of maintenance work and access has been carried out, including installation of telecommunication equipment, the roof has an adequate load capacity to carry out maintenance work subject to the stated limitations of live load
205 At 3.5 of their report Dr Anstice and Mr Wolski opined that it could be inferred from the respondent's statements to the applicant concerning access by EWP and tethered harness that all access to the roof was unsafe until the handrail works had been completed. At 5.0 they opined that Seqwater practice was for 5 persons and equipment to conduct an external and internal inspection of the reservoir, constituting 5 average sized persons (5x95 kg = 475 kg) plus 120 kg of equipment. The experts continued:
5.0…… In gross load terms, and following Seqwater's instruction as to the number of people (5 no.) required to access the slab at any one time, the slab has marginally sufficient capacity (595 kg theoretical applied load, 600 kg allowable capacity) to support the Seqwater maintenance workers and equipment load discussed in the above paragraph.
Seqwater maintenance loads can be applied to any accessible area on the roof provided the total load does not exceed 600 kg and the average load over any 5 sq m does not exceed 37.6 kg/sq m. Local load concentrations are acceptable, i.e. two men can stand together, but this does have limitations. These limitations are now more significant as the whole roof is approaching maximum allowable load.
206 Dr Anstice and Mr Wolski concluded as follows:
Conclusions
Based on the findings of the investigations as detailed in responses herein, it is concluded that Seqwater currently only has 600 kg of live load capacity available to it to undertake essential maintenance requiring access to the roof of the reservoir. Based on Seqwater's advice that this maintenance involves use of 5 maintenance staff and associated equipment, estimated to equate to approximately 600 kg of load, Seqwater currently only has marginally sufficient roof live load capacity available to it to undertake this essential maintenance.
Further, it can therefore be concluded that any additional loading of the roof from telecommunications or other infrastructure being installed on the roof of the reservoir will reduce the available roof live load capacity for maintenance activities to below the minimum of 600 kg required for maintenance activities, and therefore detrimentally impact Seqwater's ability to undertake essential maintenance required to ensure a continuous supply of drinking water to the surrounding community.
It is concluded that a lack of third party professional oversight on the design and installation of telecommunications equipment on the roof and uncontrolled access to this equipment has created an indeterminate risk for Seqwater in terms of the physical durability of the roof slab.
The combination of reduced available load for Seqwater to carry out their work on their structure and
Seqwater's responsibility to manage the impairment of their asset from the actions of others must have a limit. It is our opinion this limit has been reached on all counts and no further telecommunication equipment should be installed on this roof.
207 Mr Wolski commented on Mr Vose's expert opinion in the following terms:
Executive summary
Mr Voss does not advance any original calculation of his own to substantiate the claim of Satellite and Wireless that their antennae will have no detrimental effects on SEQWATER's use of the reservoir roof. Possibly this is because he claims the original design drawings he was provided were illegible.
The basis of Mr Voss' report is manipulation of GHD data and assumptions to attempt to demonstrate the roof is structurally adequate to carry the current and additional antennae loads while leaving a residual live load capacity. He does not specifically address the essential requirement for SEQWATER to place maintenance live load on the roof and the cumulative effect of antennae to reduce this ability. There is a disagreement in fact between us in that Mr Voss, who has not personally visited the site, claims there are 16 existing antennae on the roof whereas I have a photo showing 41 antennae.
Notwithstanding his significantly more positive opinion of mounting additional antennae, his summary recommends non destructive testing of the roof structure to assess the actual material properties that would allow a more accurate assessment of the load capacity of the slab. He does not warrant the structural capacity of the slab but selectively uses the GHD data to give a more favourable estimate of its possible residual live load capacity.
Mr Voss does not address other issues raised in the GHD memo such as long term durability or restricted rooftop access which would prejudice SEQWATER use of the space.
Specific Matters
Analysis
The statement by Mr Voss that GHD has made no supporting calculations is not true and taken out of the context where the GHD memo in section 3.1 advises that no analysis has been carried out on the slab. Our advice was intended to report that we had not completed numerical modelling of the bending behaviour of the roof slab with the non design load pattern of the antennaes. We have completed calculations of the slab's theoretical bending capacity based on the information in the original design drawings using rules from the current concrete code, and then reverse calculated from this result to determine a theoretical allowable uniformly distributed (UDL) live load.
We have then used this UDL to calculate a total allowable live load on the roof, taken off the estimated mass of all the antennae and made some conservative assumptions about relative distribution about antennae loads and other live loads, to determine what a reasonable theoretical live load is left available for use by SEQWATER to carryout maintenance activities.
Load= Bending stress (bending moment in technical terms). Mr Voss appears to agree with all of the above load and area assumptions and then checks them using a very accurate analytical method (finite element) to conclude that the difference in bending behaviour between the slab with the design UDL and the slab with the GHD adjusted pattern load is less than 2%. We therefore agree that provided the underlying assumptions are strictly correct, we can use calculation of residual live load to gauge an approximate lower bound of roof slab live load capacity.
Disagreement of facts
Mr Voss uses a report from his client Satellite and Wireless Pty Ltd to state that there are 13 antennae on the roof. Using the above GHD methodology on this basis he determines there is a significant available live load capacity on the roof. I disagree with the number of 13 antennae on the roof. I have was on the roof in September 2017 inspecting antennae fixings and noted a large number of installations. A count of antennae from a GHD drone photo of that time shows 41 antennae.
Agreement of facts
We agree that the actual load pattern of the antennae is complex and antennae fixed to the wall of the reservoir would result in some increase in available residual live load. We agree control of future installations with professional oversight (checking, documentation and as built inspection) would result in installations having no deleterious effect to the roof.
The implication of this however is that there must be a limit to third part live load that can be accepted on the roof without compromising the essential requirements of the asset owner to use the roof for its intended purpose. The additional implication is that the onus of investigation and warranty must be with the proponent.
Disagreement of risk management
Mr Voss and myself disagree sharply on how we recognise and recommend management of the risk to the slab from overloading. We agree the slab will not catastrophically collapse as a result of one too many antennae bolted to the roof or a third party maintenance team not aware of (or able to judge) load limits, crowding on the roof (the more likely risk). The slab will give ample warning by cracking and permanently deflecting (dishing in) that it has been overloaded. Even approaching final failure it will form a catenary and hang like a net from the supporting walls.
The real risk from overloading is the public health risk and extreme commercial loss to SEQWATER that a cracked slab or one that ponds unsanitary water, leaking into the reservoir. This could go unnoticed for a long time.
Due to this extreme and likely risk, I take a very conservative approach to any calculations concerning allowable live load as there is a wide range of real world ignorance and variability underlying the mathematically accurate models we develop. This is why design codes have factors of safety to account for all of these unknowns.
Mr Voss has the view that as long as the calculated allowable load value is less than a theoretical threshold, that is proof enough that the proposal is acceptable. Using the agreed GHD methodology in adjusting UDL we seem to agree that the residual live load available on the roof for use by SEQWATER is within 1% on the safe side of a theoretical limiting value. Mr Voss goes on to say that if this is perceived as cutting it a bit fine, a "significant structural reserve is inherent in the structural design of the high level water tower roof". The inference is that the proponents may reduce the regulated factors of design safety to justify a risk of overload. I strongly disagree with this approach as it is not in accordance with responsible engineering practice.
Late in his report Mr Voss recommends non destructive testing of the concrete and reinforcement in the roof as a means of reducing the unknown vales of calculation inputs and thus obtaining a more accurate theoretical value of roof slab load capacity. It is true this testing will improve the confidence of the accuracy of our calculations but it would not account for major variables such as placement of the reinforcement within the slab and the actual load pattern of antennae on the roof.
While I do not suggest the material testing not be done, when the final result is within a few percent of acceptable or not and the risk consequence so high, the most direct means of performance measurement is warranted. Measure what we need to know, which is how the roof behaves under live load. This can be done by slowly loading up the roof with shallow water filled wading pools while measurements with strain gauges will keep the roof deflection safely within its elastic limit (no permanent harm done to the roof). We will then have indisputable real world behaviour from which to extrapolate what a maximum allowable live load would be.
208 In a subsequent memorandum Mr Wolski materially stated:
1. In estimating the average mass of existing antennae equipment on the roof of the Alexandra Hills water reservoir, I have used internet sources of equipment tabulated data to make this estimate. My calculation included an allowance for the mass of ancillary items such as cabling, mounting posts and brackets. I do not wish to change my estimate of the average total mass per antennae of 25 kg each as advised in earlier correspondence.