Background
7Lahey is a builder. By a "Subcontract Agreement" dated 20 April 2011 ("the Subcontract"), Lahey engaged Trident to carry out earthworks at North Beach Bathers Pavilion in Wollongong.
8Under the Subcontract, Trident agreed to carry out the earthworks for a lump sum of $591,831.
9Trident claims (and the Adjudicator determined) that there was a variation to the scope of works under the Subcontract in respect of certain excavation ("the Excavation Variation"). The Adjudicator determined Lahey should pay Trident $71,417.50 ("the Sum") in respect of the Excavation Variation.
10Lahey's position before the Adjudicator was that, amongst other arguments, Trident was not entitled to the Excavation Variation because Trident had not complied with certain contractual conditions precedent. Thus, Lahey argued, Trident was contractually barred from making the Excavation Variation ("the Bar to Variation Point").
11Clause 40 of the Subcontract dealt with variations. It provided that if Trident: -
(1)was given a direction to "vary the work" by Lahey, such direction would not itself "constitute a variation";
(2)considered "a variation applies" it "must claim a variation" within 2 days of the direction "otherwise it shall be barred";
(3)was of the opinion that a direction was a variation, even if not expressly so identified, it "shall within 2 days of receiving the direction" notify Lahey "of its opinion in writing"; and
(4)did not give the notices required by cl 40 strictly in accordance with cl 40, then Trident "shall not be entitled to make any Claim with respect to the direction".
12Clause 46 also dealt with "Time for Notification of Claims". Arguably, that provision did not apply to claims for variations; in any event, it is not necessary to consider that matter for present purposes.
13On 20 June 2011 Lahey gave Trident a site instruction as follows: -
"Find attached [the geotechnical engineer's] recommendations for slope stabilisation where you are unable to achieve the 1:1 benching due to protected trees and other obstructions.
These recommendations are based on the site inspection on 17/06/11, of the retaining wall excavation...
Please note that this direction is not a variation to your contract.... Should you consider that this direction is a variation, you need to inform us in accordance with your contract conditions."
14It was common ground that this instruction amounted to a direction by Lahey to Trident to implement the recommendations made by the geotechnical engineers. The content of those recommendations were not in evidence before me.
15Later on 20 June 2011, Trident replied to the site direction as follows: -
"Please refer to our contract all shoring is a variation charged at $50.00 per m2 plus GST. We will require a variation to be issued prior to commencement of works."
16The work that Trident ultimately performed, and which gave rise to the Excavation Variation, was not "shoring". In those circumstances, there is an issue between the parties, not necessary for me to resolve, as to whether Trident's email of 20 June 2011 amounted to a notice of the kind called for by cl 40 of the Subcontract, as set out at [11] above.
17Later on 20 June 2011, Lahey replied to Trident's email as follows: -
"Trident have to provide a safe excavation for other trades to work within, this is governed by Australian Standards and Work Cover COP. This could be benching/shoring or in this case cyclone fencing is provided as a recommendation by [the geotechnical engineers].
As experienced Civil Engineering Contractors, what are your proposals to make these excavations safe as required by legislation?"
18It is Lahey's case that, by this email, Lahey was suggesting that the relevant works could be carried out by benching or shoring, that it was up to Trident to make a proposal as to which course should be followed and that Lahey was making it clear it did not accept that the proposed work constituted a variation. Again, it is not necessary for me to express an opinion about that submission.
19On 30 June 2011, Lahey wrote to Trident: -
"Further to our discussions today regarding the retaining wall excavation, the most important factors to consider is [sic] the stability of the existing slope and the safety of workers underneath it. The [geotechnical engineer's] report was provided as a suggestion, the final stabilisation solution needs to be determined by Trident or your own Geotech Consultant.
You need to provide us with a method and product that suits the site conditions, provides the tensile strength to prevent excavation collapse, falling rocks and any other hazard protection needed, so we can detail and construct the retaining walls."
20Lahey submitted that this communication was "only a suggestion" and that Lahey was making clear that it considered that the proposed retaining wall excavation was part of the scope of works under the Subcontract, and was not a variation.
21Mr Harry Hatzitanos, from Trident, stated in a document before the Adjudicator: -
"I went to the site on the 1st of July 2011 and showed [Lahey's representative] the samples and explained that this would not fix the problem of a possible slide of the embankment as the only solution to that was to shore, so he asked me to excavate it a bit further back just so that they would have a bit more room to move, I explained to him that this will incur further expense as it would involve more excavation and more backfilling and that we could only backfill with granular fill which would not require compaction with a vibration plate as this would eliminate the fear of collapse of material.
[Lahey's representative's] response to that was [to] go ahead as it would be a cheaper option so we went ahead."
22There is no suggestion in Mr Hatzitanos's statement that he was then contending that the works to be done constituted a variation.
23The relevant work was carried out in July 2011.
24On the evidence before me, the next communication from Trident to Lahey about this work was the service of a payment claim pursuant to s 13 of the Act on 25 September 2012 ("the Payment Claim"); some 14 months after the work had been done.
25The Payment Claim annexed an invoice dated 24 August 2012 numbered 1697 from Trident to Lahey which, amongst other claims, claimed the Sum as follows: -
Extra Works Over excavation to retaining walls 60.00 17,490.00
265m3 @ $60.00 per m3
Extra Works Removal of additional spoil 265m3 @ $45.00 per m3 45.00 13,117.50
Extra Works Backfill with granular fill 265m3 @ $140.00 per m3 140.00 40,810.00