TRADING TERMS AND CONDITIONS
These Trading Terms and Conditions (“Terms”) apply (unless otherwise previously agreed in writing) to the supply of Services by Durkin Constructions Pty Limited (“Durkin”) to a Client from time to time. Any supply of Services by Durkin to the Client made after the date of acceptance of these Terms is a supply pursuant to the supply agreement constituted by these Terms and the relevant Order accepted by Durkin (“Agreement”) and any such supply does not give rise to a new or separate agreement.
INTERPRETATION
1. In these Terms unless the contrary intention appears:
Additional Charges includes all delivery, handling and storage charges, goods and services tax, stamp duty, interest, legal and other costs of recovery of unpaid money and all other government imposts and all money, other than the Fees, payable by the Client to Durkin arising out of the performance of the Services.
Client means the person to or for whom the Services are to be supplied to by Durkin.
Confidential Information includes any information which is not publicly available and relates to processes, equipment and techniques used by Durkin in the course of Durkin’s business and provision of Services including all information, systems, data, drawings, specifications, documentation, source or object code, designs, construction, workings, features and performance notes, techniques, concepts not reduced to material form, schematics, proposals and intentions and technical data.
Fees means the list price for the Services as charged by Durkin at the date of delivery or such other price as may be agreed by Durkin and the Client or advised by Durkin.
Intellectual Property includes registered or unregistered trademarks, patents, domain names, copyrights, processes, know-how, registered designs or other like rights or any right to apply for registration of any of the former.
Order means the purchase order made by the Client for the supply of Services by Durkin.
Services means the Services as specified by Durkin to the customer in the customer’s Order.
2. ORDER FOR SERVICES
2.1 The Order constitutes an offer by the Client to purchase Services in accordance with these Terms.
2.2 An Order given to Durkin is binding on Durkin and the Client, if:
2.2.1 a written acceptance is signed for or on behalf of Durkin; or
2.2.2 the Services are supplied by Durkin in accordance with the Order.
2.3 An acceptance of the Order by Durkin is then to be an acceptance of these Terms by Durkin and the Client and these Terms will override any conditions contained in the Client’s Order. Durkin reserves the right to accept a part only of any Order by notifying the Client in writing or by performing the Services to the Client. No order is binding on Durkin until accepted by it.
2.4 The Client must, as a minimum, provide Durkin with a copy of its Order or alternatively written agreement for Services before Durkin commences any work. No project will commence without an order number supplied.
2.5 An order which has been accepted in whole or in part by Durkin cannot be cancelled by the Client unless it is made in writing and is delivered by post, hand delivery or facsimile or email to Durkin. The Client is liable to reimburse Durkin for the costs it has incurred for labour and materials in fulfilling the Purchase Order up to the date the requested for cancellation is received and acknowledged by Durkin.
2.6 Any quotation given by Durkin is only valid for 60 days from its date of issue and shall not constitute an offer.
3. SUPPLY OF SERVICES
3.1 Durkin shall supply the Services to the Client in accordance with the Order and any specifications provided by the Client provided they comply with any applicable law or regulatory requirement at the time of the Services.
3.2 The supply of Services is conditional on the Client providing all the necessary information to perform the Services.
3.3 Durkin shall use all reasonable endeavours to meet any performance dates specified in the Order, but any such dates shall be estimates only and time shall not be of the essence for performance of the Services.
3.4 Durkin reserves the right to amend the Order if necessary to comply with any applicable law or regulatory requirement and Durkin shall notify the Client in any such event.
3.5 Durkin warrants to the Client that the Services will be provided using reasonable care and skill.
4. FEES AND CHARGES
4.1 The Fees for the Services are as set out in the Order or calculated in accordance with Durkin's current price list at the date of the Contract available on request and are payable to Durkin.
4.2 A credit account is only available to the Client if they have completed a Credit Application Form which has been processed and approved by Durkin. Until this Credit Application Form is approved or where no Credit Application Form has been submitted, then Durkin shall invoice the Client and the Client shall pay each invoice submitted by Durkin in full in advance of the Services being supplied.
4.3 Subject to prior Credit Approval in accordance to Durkin’s credit control practices, unless agreed otherwise, Durkin will issue an invoice to the Client which shall be payable in full within 30 days of the date of the invoice. Interest is charged at the rate of 10% per annum for each day from the expiry of that period that payment is overdue, and any legal fees incurred to recover overdue payments.
4.4 All amounts payable by the Client are expressed exclusive of Goods and Services Tax (GST), except as otherwise specified. If GST is payable by Durkin on Fees invoiced, the Client must pay Durkin an amount equal to that GST in addition to the Fees on receipt of a GST tax invoice.
4.5 All amounts payable by the Client under these Terms must be paid full without any set-off, counterclaim, deduction or withholding (other than any deduction or withholding of tax as required by law) of any kind.
4.6 Any changes or additions to the Services will be subject to Fees and Additional Charges.
4.7 If the Client is in default, Durkin may at its option suspend performance of any further Services or cancel an agreement without prejudice to any of its existing rights.
4.8 If the Client arranges for a third party to pay any of Durkin’s fees or charges, the Client remains liable to the extent that the third party does not pay in full by the due date.
5. BUILDING AND CONSTRUCTION INDUSTRY SECURITY OF PAYMENT LEGISLATION
5.1 The Client acknowledges and agrees that:
5.1.1 Durkin may from time to time serve payment claims in accordance with the Building and Construction Industry Security of Payment Act 1999 (BCISPA) (as amended from time to time) on the Client for Services supplied in New South Wales; and
5.1.2 Durkin may from time to time service payment claims on the Client for Services supplied outside of New South Wales in accordance with the relevant Building and Construction Industry Security of Payment Act of the State or Territory (as amended from time to time) in which they were supplied.
6. DELIVERY
6.1 Durkin shall use reasonable endeavours to provide the Services within a reasonable timeframe and subject to receiving all relevant information from the Client or otherwise as agreed. Durkin may perform the Services at any time on any agreed day. If Durkin is requested by the Client to perform the Services at a particular time, Durkin may agree to the request and may levy Additional Charges to cover any additional cost to do so.
6.2 Durkin shall not be liable for delays in performance or failure to provide the Services where delivery is not reasonably possible due to circumstances not caused by Durkin and which are beyond Durkin’s reasonable control.
6.3 Notwithstanding any delay in the delivery or performance of those Services the Client is still obliged to accept or pay for the Services.
7. WARRANTIES
7.1 Durkin’s liability is limited to, to the extent permissible by law and at Durkin’s option to:
7.1.1 the supply of Services again; or
7.1.2 the payment of the cost of having the Services supplied again.
7.2 Any claims to be made against Durkin for the failure of performance or delivery of Services must be lodged with Durkin in writing within 7 days of the delivery or agreed performance date.
7.3 To the extent permitted at law, all other warranties whether implied or otherwise, not set out in these Terms are excluded and Durkin is not liable in contract, tort (including, without limitation, negligence or breach of statutory duty) or otherwise to compensate the Client for:
7.3.1 any increased costs or expenses;
7.3.2 any loss of profit, revenue, business, contracts or anticipated savings;
7.3.3 any loss or expense resulting from a claim by a third party; or
7.3.4 any special, indirect or consequential loss or damage of any nature whatsoever caused by Durkin’s failure to complete or delay in completing the order to perform or deliver the Services.
8. DISPUTE RESOLUTION
8.1 If a dispute arises in connection with this Agreement, a party to the dispute may give to the other party to the dispute notice specifying the dispute and requiring its resolution under this clause (“Notice of Dispute”).
8.2 If the dispute is not resolved within 7 days after the Notice of Dispute is given to the other party, each party to the dispute must nominate 1 representative from its senior management (“Representative”) to resolve the dispute.
8.3 If the dispute is not resolved within 7 days of the dispute being referred to the Representative (First Period), the dispute must be submitted to mediation by a mediator acceptable to the parties, or absent agreement, by a mediator nominated by the President of the law Society of New South Wales from time to time.
8.4 While any such dispute remains unresolved the parties agree to continue the performance of the Agreement to the extent that such performance is possible given the nature of the dispute, in particular the Client agrees to make payments under this Agreement as they fall due and payable.
8.5 This clause does not prevent any party from obtaining any injunctive, declaratory or other interlocutory relief from a court, which may be urgently required, but otherwise no proceedings until mediation process completed.
9. INTELLECTUAL PROPERTY AND CONFIDENTIAL INFORMATION
9.1 All Intellectual Property in or arising out of or in connection with the Services (other than Intellectual Property in any materials provided by the Client) and any works or deliverables executed from them is owned by Durkin except where otherwise indicated. This shall include but is not limited to the format, layout, text, images and set up of the surveys, images and tests.
9.2 Unless otherwise permitted by law, the material and deliverables (including but not limited to the surveys, tests, images, reports and other data produced by Durkin) must only be used in the format provided and for the sole purpose of the Client’s business or operations and may not otherwise be copied, reproduced, displayed or distributed to any third parties in whole or in part without prior written approval from Durkin.
9.3 Unless required by law or otherwise agreed, the Client must keep confidential all information (including but not limited to Confidential Information) it receives from Durkin which relates to the Services, Durkin’s business or any other Services Durkin provides and any of Durkin’s Intellectual Property, other products or processes except to the extent that the information is in the public domain.
10. DURKIN PERSONNEL
10.1 The Client agrees to not solicit employees or personnel of Durkin. Any attempt to solicit employees or personnel from Durkin would be seen as a breach of these Terms and the Client may be liable for all expenses relating to the recruitment and training of a new employee.
11. TERMINATION
11.1 Durkin may on written notice immediately terminate an Order, agreement and/or the Client’s credit account if the Client:
11.1.1 fails to pay an invoice when due;
11.1.2 breaches these Terms or an agreement between the Client and Durkin; or
11.1.3 becomes or threatens to become insolvent or subject to any form of external administration.
11.2 The Client may on written notice to Durkin terminate an Order or agreement with Durkin in the event of a material breach by Durkin of its obligations under such Order or agreement and such breach has not be remedied within thirty (30) days of written notice from the Client requiring the breach to be remedied.
11.3 If Durkin terminates an agreement with the client under clause 9.1 or if the client terminates an Order or agreement under clause 9.2 then:
11.3.1 Durkin’s obligations under it are at an end;
11.3.2 Durkin’s accrued rights and remedies are not affected;
11.3.3 Durkin may retain all monies paid under it; and
11.3.4 Durkin may invoice the Client, and the Client must pay, for all Services provided up to the termination date.
12. INDEMNITY
12.1 To the full extent permitted by law, the Client will indemnify Durkin and keep Durkin indemnified from and against any liability and any loss or damage Durkin may sustain, as a result of any breach, act or omission, arising directly or indirectly from or in connection with any breach of any of these Terms by Client or its representatives.
13. SECURITY INTEREST
13.1 The Client grants a security interest in all of its present and after acquired property and in all of its present and future rights, title, estate and interest, whether legal and equitable, in relation to any personal property, including any debts owed to the Client, in favour of Durkin to secure the performance of its liabilities and obligations hereunder or on any account whatsoever.
13.2 For the purpose of this clause and other relevant clauses in this Agreement “PPSA” means the Personal Property Securities Act 2009 and the expressions “accession”, “collateral”, “financing statement”, “financing change statement”, “security agreement”, “security interest”, “perfected security interest” and “verification statement” have the meanings given to them under, or in the context of the PPSA.
13.3 If requested by Durkin the Client must immediately sign any documents, provide all necessary information and do anything else required by Durkin to ensure that the security interest created in Durkin’s favour is a perfected security interest.
13.4 The Client must not grant any other security interest in favour of any party until Durkin has perfected its security interest created under this Agreement.
13.5 The Client must not do or permit anything to be done that may result in the security interest granted to Durkin ranking in priority behind any other security interest.
13.6 To the fullest extent permitted by the PPSA the Client agrees to contract out of the application of the provisions listed in sections 115(1) and 115(7) and the sections listed therein shall not apply.
13.7 The Client hereby waives any rights the Client may otherwise have to:
13.7.1 receive any notices or statements the Client would otherwise be entitled to receive under sections of the PPSA including for the avoidance of any doubt the sections referred to in sections 115(1) and 115(7) of the PPSA;
13.7.2 apply to a Court for an order concerning the removal of an accession under section 97 of the PPSA;
13.7.3 object to a proposal of the Client to purchase or retain any collateral under sections 130 and 135 of the PPSA; and
13.7.4 receive a copy of a verification statement confirming registration of a financing statement, or a financing change statement, relating to any security interest created under this document.
14. GENERAL
14.1 These Terms are to be construed in accordance with the laws from time to time in the State of New South Wales and the Commonwealth of Australia. The parties submit to the non-exclusive jurisdiction of the Courts of New South Wales, Australia and any courts which may hear appeals from those courts in respect to any proceedings in connection with these Terms.
14.2 These Terms contain all of the terms and conditions of the contract between the parties and may only be varied by agreement in writing between the parties.
14.3 Any conditions found to be void, unenforceable or illegal may, to that extent be severed from the Agreement.
14.4 No waiver of any of these Terms or failure to exercise a right or remedy by Durkin will be considered to imply or constitute a further waiver by Durkin of the same or any other term, condition, right or remedy.
15. SUI SURVEYS
15.1 Durkin recommends that the most recent Dial Before You Dig (DBYD) plans are requested for each site. This can be done by the Client or by Durkin (Durkin prefers to obtain review and consolidate the DBYDs in-house and ensure they are legible and current). It is a legal requirement to have current Electricity and Gas DBYD plans for any excavation greater than 150mm deep. If DBYD’s are obtained by the client they must be at a scale that enables the plans to be read on site
15.2 Durkin will obtain DBYD plans if requested by the Client. An additional fee will generally be charged to obtain and analyse the plans, generate a DBYD Master file and make available to the site crews prior to commencing the field works.
15.3 The DBYD plans generally show the position of Mains only, and service connections to individual properties are not generally shown. If the Client has plans indicating the Services within their property, they should be made available to Durkin 5 days prior to the start of work.
15.4 Durkin are accredited DBYD Locators and have over 15 DBYD Certified Locators. Only DBYD Certified Locators can locate Telstra and Optus services in New South Wales (NSW).
15.5 If the DBYD application returns a positive notice for VIVA Energy, they must be contacted before any excavation works take place regardless of distance from the excavation site.
15.6 Verizon insist on sending one of their Contractor’s to site to unlock their pits and relock the pits after Durkin have located the asset. They will not provide a price list, but charge per job once the details are known. The cost is generally estimated to be over $1000.00 per day plus GST. Durkin will advise the quantum of any costs once they are known. If Optus is located within the work area, Durkin will complete a “Optus Asset Location Advice” sheet and forward it to Optus for record keeping.
15.7 Major distribution fuel lines need to be located by the relevant Pipeline Inspector depending upon who owns the pipeline. The DBYD plans received will advise of the relevant contacts to facilitate this. Costs can apply for this service, particularly at night. The DBYD plans received will advise of the relevant contacts to facilitate this. The Pipeline Inspector need to attend any potholing works. Costs can apply for this service, particularly at night.
15.8 Major gas pipelines such as the Ethane pipeline that deliver gas from the Moomba gas field in South Australia to NSW need to be located by the relevant companies Pipeline Inspector. The Pipeline Inspector need to attend any potholing works. Costs can apply for this service, particularly at night.
15.9 Ausgrid and Endeavour Energy insist on having an Ausgrid Supervisor on site if any of their pits or Sub Stations need to be opened to track their cables. The cost is estimated to be over $1000.00 per day plus GST (dayshift) and can be over $2,000 per night. Durkin will advise the quantum of any costs once known.
15.10 If potholing of Jemena High Pressure Gas Lines or Ausgrid/Endeavour Energy Transmission cables is required, a Jemena/Ausgrid/Endeavour Supervisor is required on site to oversee the works. Both companies charge for the supervision and the cost is estimated to be above $1,000.00 (>$2,000.00 per night) per day. Durkin will advise the quantum of any costs once known.
15.11 ElectroMagnetic (EM) location can only accurately track metallic pipes. Plastic, concrete, asbestos or earthen‐ware pipes cannot be tracked unless they have a tracer wire attached to them. Even if a tracer wire is attached, the accuracy of the trace can be limited, as the signal tends to “jump” to better conductors if they are in close proximity. It can be difficult to track pipes and cables under heavily reinforced concrete slabs as the signal tends to “jump” onto the rebar.
15.12 Sewers, Storm‐Water pipes and Sewer pipes can be traced using EM equipment with Flex Rods and Sondes. This requires us to be able to access the pipe from pits or manholes. The crews are equipped with Gatic lifters and Telstra pit keys. Covers which are rusted into position or heavier than 50kg cannot be lifted by our crews. If a 1-man crew is required on site, assistance will need to be given by the Client when lifting heavy pit covers.
15.13 Only Free Flowing Storm water and Sewer Pits/Pipes can be tracked via Flex Rods and Sonde provided that they are not too deep. 3-5m depth is usually the maximum depth that a sonde can be located accurately. Pits and pipes which are backed up need to be cleaned prior to locating. GPR can locate blocked pipes provided that they are not too deep. Sewer branch lines are often difficult to detect as they are generally too deep to be seen with GPR and are difficult to rod unless rodding points are on the branch line.
15.14 Ground Penetrating Radar (GPR) Locating can track non‐metallic pipes. The effectiveness of GPR locating is highly dependent upon the soil type. It is generally very effective in sandy soils, but can have limited effectiveness in very heavy clay soils. GPR signals can struggle to penetrate through reinforced concrete slabs. Highly saline environments can also affect signal penetration. There is a conflict between resolution and penetration, i.e. a high frequency antenna can locate small diameter pipes at shallow depths, but its depth of penetration can be limited to 300-500mm in heavy clay soils. Low frequency antennae can penetrate deeper into the ground but often cannot detect small diameter pipes.
15.15 As no single tool can provide the best solution, Durkin recommend the use of both GPR/EM equipment for all jobs.
15.16 Experience around the world has shown that “best practice” using EM/GPR equipment in combination should result in detection rates of 80‐95%. Durkin cannot guarantee that Durkin will locate all mains/Services on a job site.
15.17 Unless the scope of the works is limited, a 2‐man crew will generally be more cost effective than a 1-man crew.
15.18 The locating accuracy is dependent upon the pipe/cable type, its depth, and the prevailing soil type. In most situations, the plan position will be accurate to within +/‐300mm, and the depth to within +/‐500mm. AS 5488 is the relevant Australian Standard for SUI Surveys. Significant outliers do occur, in particular for depth measurements. Potholing is required by the Utility Authorities to confirm the plan position/depth of any Mains.
15.19 AS 5488 stipulates 4 Quality Levels (D, C, B, A) and electronic locating to QL-B only recognises the use of EM equipment in Direct Connection mode, Flexitrace/Sonde, Flexitrace/Sonde, and in certain cases Induction. Only clean signals can be recorded as QL-B. To supplement the Quality Levels in AS5488 Durkin have created their own internal Quality Levels (X, Y, Z) to allow the use of locating equipment/techniques which don’t conform to AS 5488 and also to record medium and low confidence locates which do not conform with the definitions in AS 5488. The cover page (attached in Annexure A) describing the AS 5488 and internal Durkin confidence levels needs to be read and understood by the Client before Durkin are engaged.
15.20 It is important to recognise that nylon/plastic gas mains and Services laid without an intact trace wire are very difficult to locate electronically. The use of GPR to track them is more effective in sandy soils (locate accuracy generally 50-80%) but is lower in clay soils (locate accuracy 25-50%). As such it is essential to pothole all gas mains and Services located to validate the data
15.21 The Gas Tracker technology can be used to increase the locate accuracy of gas mains and Services. Its use requires permission from property owners to temporarily disconnect the gas supply to their property (generally 30-45 minutes) so that a licensed plumber can attach the Gas Tracker transmitter to the gas pipe riser and send a trackable pulse down the pipe. Once the locate is complete the meter is reconnected, and the boiler relit if necessary. The Gas Tracker is used in conjunction with GPR and can get the locate accuracy up to 90-100%. The Gas tracker works well when nylon/plastic pipes are in direct contact with the surrounding soil. The signal is weakened/lost if the pipe is inserted into a steel/cast iron or a plastic sleeve.
15.22 The only point of certainty in any SUI survey is where the utilities are exposed in either a pothole or a pit where the 3D position can be accurately measured with tapes or survey equipment. The individual Utility authorities specify potholing frequencies for their assets (every 5m for Telstra). It is the Client’s responsibility to review the requirements of the Utility companies and arrange potholing before construction at their stated frequency. Care needs to be taken with interpolating utility positions between potholes/pits as straight lines as the depth and plan position can vary considerably from a straight line.
15.23 Durkin will use reasonable care and skill to utilise all electronic locating equipment to maximise SUI survey accuracy and guarantee that all SUI Engineers/Technicians will follow the Quality Procedures that they have been trained in. As outlined above Durkin cannot guarantee Durkin will find all Sub Surface Utilities as some are not traceable electronically. Durkin will advise the Client of any mains shown on DBYD that Durkin cannot locate, and any other Sub Surface Utilities that are indicated by visual indicators such as valves, pits, trenches but which cannot be electronically located.
15.24 Electronic Locating can be difficult in private properties particularly schools, universities, hospitals and factories. The Sub Surface Utilities are generally not shown on DBYD plans and the routes of the Utilities can be random. Universities and Hospital’s in particular have a high density of Sub Surface Utilities. Whilst Durkin allow for a significantly reduced productivity rate on these sites due to the complexity, any as built service drawings assist considerably in maximising locate accuracy and Durkin encourages the Client to use their best endeavours to obtain any such drawings. It is very important to advise Durkin immediately if any utilities are found not shown on the Durkin Utility maps so Durkin can trace the utilities found and update the map.
15.25 On occasion, underground utility Services are buried within the bound layers in a road pavement, or just underneath them. As power tools are required to break out the bound layers, damage can occur to the utilities when using best practice potholing techniques. If Services are damaged in this manner, Durkin will not be liable for any actual, direct, indirect or consequential costs or loss arising from the damage.
15.26 Durkin will set pressures for Non-Destructive Digging (NDD) trucks as per the allowable pressures suggested by the relevant Utility Durkin. Durkin takes no responsibility for any damage that occurs to a pipe/cable/conduit by using the NDD equipment correctly and at the correct pressure.
15.27 If a Client finds Sub Surface Utilities on site which are not marked by Durkin, or cannot find Sub Surface Utilities Durkin, that have marked, they must contact Durkin, immediately so that one of our SUI Technicians/Engineers can go back to site to investigate and resolve.
15.28 All pavement reinstatements are considered temporary.
DISCLAIMER
15.29 Due to the limitations of the equipment as described above, there will on occasion be no indication of the presence of underground objects, cavities or concealed Services, including pipes or cables. The environment can also hinder or prevent accurate feedback or information. Trained staff will determine the location and position of concealed objects, cavities and Services, to the best of their ability with the latest equipment. All results relayed to the Client will be the most accurate information possible, for the Client to then use at their discretion. Durkin will not be liable for actual, direct, indirect or consequential loss or costs incurred by the Client due to the existence of undetected objects, cavities or Services.
16. ENGINEERING SURVEYS
16.1 To provide enough lead time to review the documents and prepare a Survey management Plan (SMP) upon a Client’s request at a cost to be advised by Durkin, the Client must provide Durkin in writing within [ 7 business ] days prior to the commencement of the field works the following:
16.1.1 Any design packages (IFC/AFC);
16.1.2 project specific survey requirements; and
16.1.3 approved departures from general survey specifications (e.g. RMS G-73 for Detail and RMS-G71 for Construction surveys, etc.)
16.2 For Conformance surveys, detailed program of site works to be supplied to Durkin 7 business days to allocate resources accordingly. Durkin prefers to be consulted at detail planning phase of construction works so that data capture dates can be allowed for in the program.
16.3 Deviations from AFC drawings/models by the client or their subcontractors to be advised to Durkin in writing. Durkin will not be liable for discrepancies between design and WAE (Works as executed) should the client or their subcontractors deviate from AFC drawings/models without formal approval of the principal client or written notifications to Durkin.
16.4 The extent and scope of survey works will be to the scope/extents confirmed in the formal fee proposal and methodology. Considering the wide range of survey activities, the scope supplied by the client to explicitly mention the type of survey works required. Where survey control points are established by Durkin on construction sites managed by the client, it’s the client’s responsibility to protect the survey controls from disturbance/damage by construction plants/material, and ensure safe access to set-up and have visuals between control points maintained.
16.5 Any project or site-specific inclusions/exclusions provided in Durkin’s proposals to be considered in conjunction with the above-mentioned terms.
17. CONCRETE IMAGING
17.1 Post Tension and Steel Reinforcement Drawings are invaluable when performing Concrete Imaging surveys. Whilst there is no guarantee that they are accurate, they give Durkin’s Engineers/Technicians a guide as to how the structure was built. The Client is encouraged to obtain these drawings and supply them to Durkin before works start on site.
17.2 Electrical and Communication ducts are often buried in concrete slabs/beams and can be difficult to locate electronically. The Client is encouraged to obtain any Work as Executed (WAE) drawings and supply them to Durkin 7 business days before works start on site. Alternatively, maintenance staff can often give advice on potential duct run locations and should be made available to discuss with Durkin staff.
17.3 The depth of penetration of Concrete Imaging equipment can be 150-300mm depending upon the rebar density and age of the concrete. It is recommended to always scan the top and bottom surface of all slabs and beams and all faces of columns to maximise detection rates.
17.4 Depth accuracy with Concrete Imaging Equipment is generally +/‐15%. Calibration to a known slab thickness or rebar/PT depth is required to gain these accuracies.
17.5 It can be difficult to see the bottom layer of reinforcement in some slabs as the top layer can “mask” the layer underneath. For suspended slabs and beams the underside of the slab/beam and the beam walls should be scanned to determine the rebar layout on each face of the concrete member. If the underside of the slabs/beams cannot be seen, there is a risk that penetrations may be made in high risks areas such as supporting beams or adjacent to a structural column. There is also a risk that pipes/cables/lights attached to the underside of the slab/beam may be damaged during the penetration process. EM equipment should also be used to confirm the location of buried Services. Pipes and cables are often “tied” to the reinforcement bars, and cannot be differentiated from the bar itself. If a decision is made to cut through reinforcement, the risk that there may be conduits, pipes or cables tied to the relevant bars needs to be considered by the Client.
17.6 Durkin recommends the use of 3D scans whenever possible as they can show buried pipes/ducts/cables not visible using 2D scans alone.
17.7 Discussions should be held with a suitably qualified Structural Engineer if any penetrations require any rebar to be cut. This is essential to ensure that the structural capacity is not affected.
17.8 It is difficult to do scans in corners of rooms and any planned penetrations in these areas should be avoided due to the risk of damage to steel reinforcement, post tensioned cables and electrical/communication Services.
17.9 The accuracy of concrete imaging reduces at anchor points due to the amount of reinforcement and the spread of the anchor cables. Penetrations in the vicinity of anchor points should be avoided
17.10 Support beams are often highly congested with Post Tensioned Cables, Heavy Reinforcement and possibly pipes and cables. It is recommended to avoid core drilling through beams due to the congestion and the loads carried by the beams.
17.11 Post Tension (PT) duct sizes are often not known. It is recommended that a 300mm exclusion zone either side of the center line of any PT cables marked is adopted for penetration purposes
17.12 An exclusion zone of +/300mm is recommended from the centre line of any suspected communication/electrical cables marked
17.13 It is important that the Client advises Durkin if any differences are found on site as compared to the plans/reports supplied by Durkin as soon as it becomes known to the Client. Durkin will mobilise staff to site once it is put on notice to investigate and update the plans if required and re-issue them.
DISCLAIMER
17.14 Due to the limitations of the equipment as described above, there will on occasion be no indication of the presence of underground objects, cavities or concealed services, including pipes or cables. The environment can also hinder or prevent accurate feedback or information. Trained staff will determine the location and position of concealed objects, cavities and services, to the best of their ability with the latest equipment. All results relayed to the Client will be the most accurate information possible and available at the time for the Client to then use at their discretion. Durkin will not be liable for any actual, direct, indirect or consequential loss or costs incurred by the Client due to the existence of undetected objects, cavities or services. In this manner, Durkin will not be liable for any actual, direct, indirect or consequential costs or loss arising from the damage.
18. PAVEMENT TESTING
18.1 Core and Bore Hole Logs represent the material encountered in the particular hole, and the holes represent only a very small sample of the entire surface area. Pavement materials can vary considerably, and care must be taken in extrapolating the Core and Bore Hole logs to represent entire road pavements. Interpretation of the information and its application to design and construction should therefore take into account the spacing of boreholes, the frequency of sampling and the possibility of other than “straight line” variations between bore holes and core holes.
18.2 Where ground water levels are measured in boreholes, there are many potential problems. In low permeability soils, groundwater although present, may not enter the hole slowly or perhaps not at all during the time the hole is left open. A localised perched water table may lead to an erroneous indication of the true water table. Water table levels will vary from time to time with seasons or recent weather changes. They may not be the same at the time of construction as are indicated in this report. The use of water or mud as a drilling fluid will mask any ground water inflow. Water has to be blown out of the hole and drilling mud must be first washed out of the hole if water observations are to be made. More reliable measurements can be made by using standpipes or piezometers
18.3 Durkin will not drill any Core and Bore Holes without obtaining current DBYD plans, and scanning the area electronically to find possible utility services in the work area. Potholing may also be required to ensure that the separation distances required by the individual Utility Companies and as stipulated in the document “Work Near Underground Assets Guide – Safework NSW 2007”. This document can be found on the Safework Website
18.4 DCP testing of subgrades gives an estimation of subgrade stiffness at the time of testing. The strength of certain subgrades are highly moisture dependent.
18.5 Engineering Reports are prepared by qualified personnel and are based on the information obtained and based on the engineering standards of interpretation and analysis as at the date of the provision of Services. Where the report has been prepared for a specific design proposal, the information and interpretation may not be relevant if the design proposal has been altered. In this situation Durkin will be pleased to review the report and the sufficiency of the investigation work.
18.6 Every care will be taken with interpretation of subsurface conditions, discussion of geotechnical aspects and recommendations or suggestions for pavement design and construction. However, Durkin cannot always anticipate or assume responsibility for unexpected variations in ground conditions (the potential for this will depend partly on bore/corehole spacing and sample frequency), changes in policy or interpretation of policy by statutory authorities, and the actions of contractors responding to commercial pressures.
18.7 In the event that conditions encountered on site during construction appear to vary from those which were expected from the information contained in the report, Durkin request that they are immediately notified. Most problems are more readily resolved when conditions are exposed than at some later stage well after the event.
ANNEXURE A - EFFECTIVENESS AND LIMITATIONS OF SUBSURFACE UTILITY INFORMATION (SUI) SURVEYS