Case Studies
Case Study 1 - SH2 Mangatawhiri Deviation
Project Owner
Transit New Zealand
Project description
Construction of an expressway on New Zealand’s most dangerous stretch of road - deviating from Mangatawhiri and re-joining SH2 at Maramarua Golf Club. The new expressway will stretch seven kilometres in total with a passing lane at the eastern and western ends along with two bridges, three cattle underpasses and one major retaining wall.
Duration
October 2006 to August 2008
Laboratory project
Multiplex Heb JV were contracted to construct the SH2 Mangatawheri Deviation. The area is renowned for Moisture Sensitive material which can make construction and testing difficult.
Brief
Stevenson Laboratory supplied services for the three key stages of the project:
Geotechnical Investigation
Earthworks – Cut and Fill
Pavement Construction
Services provided
The geotechnical investigation was carried out over a very short Christmas period. The investigation involved over 40 test pits each logged with samples taken for further Lab testing.
The sampling generated over 100 Standard Compaction and Shear Vanes along with over 60 Hand Augers and 400 water contents. Staff worked through Christmas and weekends to complete testing so that test data could be analysed and applied to design before the project was due to start in February 2007.
The Earthworks required over Two Thousand Nuclear Densometers, Shear Vanes and Scalar sets.
The Pavement Construction required over One Thousand Nuclear Densometers
Challenges
The contractor had tight deadlines to meet, due to the construction start dates. All laboratory tests from the Geotechnical investigations needed to be completed in time.
Stevenson Laboratories worked closely with the site engineer to ensure every single structural layer (from the bulk fill up to the base-course level) of approximately 200 to 300mm, was tested thoroughly. This had to be completed before the road was sealed in August 2008.
Benefits to client
Accurate results, 24/7 availability and the prompt service, enabled the engineers to make critical decisions on the spot. This enabled the project to be completed six months short of the due date for completion.
Case Study 2 - AIAL (Auckland International Airport Limited)
Project Owner
AIAL (Auckland International Airport Limited)
Project descriptionHardstands and Runway Extensions
DurationAt intervals during the past six years (since 2000).
Laboratory projectTest concrete samples made at Auckland Airport by Firth Concrete technicians at Firth on-site mobile batching plant and then delivered to Stevenson Laboratory for testing.
BriefStevenson Laboratory were asked to carry out large volumes of 4,7 and 28-day aged Flexural Tensile testing on 100 x 100 x 400mm moulded concrete beam specimens and to return result data on the same day.
Services providedHardened concrete testing, flexural tensile strength and density testing.
Benefits to client
Provision for accommodating large volume storage of specimens coming into the lab for testing. Meeting this challenge involved designing and building new mobile storage and curing tanks at short notice to deal with several large trials.
Fast turnaround – all testing had to be completed within pre-arranged timeframes.
Case Study 3 - Waikato Northern Landfill – Hampden Downs
Project
Waikato Northern Landfill – Hampden Downs (60k south of Auckland)
Project OwnerFulton Hogan/Enviro Waste Services
SubcontractorTwomey Construction
Engineering ConsultantsFraser Thomas Engineering
Duration of testingSince October 2004
Services providedTwomey Construction were sub-contracted to construct an impermeable clay liner, new hardstands and cell foundations for the landfill. Stevenson Laboratory were asked to test in situ soil strength and density to confirm that the clay compaction was resulting in a structure of the correct density to meet landfill requirements to prevent toxic leakage.
ChallengesTo provide short notice testing service, requiring large volumes and quick turnaround (same day or 24hr return on results). The client was faced with a short earthwork season in which to complete a specified number of cells ready for use by the landfill operation. The laboratory made a commitment to the client, giving them assurance that we would arrive on site within two hours of any request. We managed to maintain this commitment over the busiest construction season in recent years, by recruiting and training only the best candidates.
Benefits to clientThe testing was completed on time. Client completed the works on site by the deadline.
Case Study 4 - Mercer to Long Swamp section of Waikato Expressway
Project
Mercer to Long Swamp section of Waikato Expressway
Project OwnerTransit New Zealand
SubcontractorStevenson Resources (supplied metal to various stages of project)
Duration of testingOver a two-year period.
Services providedStevenson Laboratory tested base course and sub base to contract specifications. We were asked to confirm that the products were compliant. This involved three test samples per 2000 tonne stockpile. Tests included sieves, sand equivalent, weathering quality index, and CBR (California Bearing Ration).
Challenges
Turnaround: Completing the tests within a tight time frame. Tests that would normally take five to seven working days were completed within four, with no loss of quality. The lab made the job a top priority. As soon as Stevenson’s Huntly Quarry notified the lab that a stockpile was ready it immediately went to collect samples to take back to the lab so that the quarry could maintain their production schedule. To meet tight deadlines, the lab hired and trained additional staff. Testing was undertaken to obtain the best and most consistent grade of aggregate. If tests failed, the stock pile would be remixed or altered to the lab’s recommendations and additional tests were undertaken before the product was released to client.
Mix designs: During the last season of the project, the lab specified mix designs and ongoing evaluation of the designs to obtain a consistent base course product.
Production delays at the quarry were minimised due to fast-testing turnaround.
The lab was able to specify mixes to guarantee consistent product quality.
Stevenson Resources were able to supply a quality product to the Expressway project.
