Installation of 3,650m of Nexus Drainage Pipe

With time constraints being an issue, Blackley Construction were engaged on a labour/ machine-only contract to install twin 1350mm Diameter concrete pipes through a stopbank. Whittikers provided the grade and alignment as the requirement was to maintain flood protection at all times. The first section of pipes had to be laid and then the stopbank relocated over top of them to provide this flood protection. The second section of pipes were then laid on foundations that included weak flowable concrete, a seepage collar and finally polystyrene.

Laying pipes on polystyrene provided many challenges as the sinkage of the pipes into the polystyrene had to be allowed for. The pipes were laid to grade and on line. Once the pipe-laying was complete, Blackley Construction relocated the stopbank a second time back to its original alignment. This was compaction tested as it was constructed, with all tests passing.

Key features of the work and/or Statistics

• The project involved us laying to grade twin 1350mm diameter concrete pipes through a stopbank to match up with the outfall of a pump chamber.
• We installed a total length of 90m of pipe.

Key equipment used:

• Compaction rollers & hand compaction equipment
• Rotary Lasers
• Kobelco SK210, SK135 & Hitachi ZX 200 excavators

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Effluent Pond Construction for Freestall Cow Barn, #4 Dairy

In-situ clay ponds require a lot of planning because weather plays a major role in the construction process as does testing the structure. A stand of Pine trees had to be removed from a gulley so excavated material from the pond could be compacted into the gulley to form one of the pond walls. Existing drainage in the area was diverted so it wouldn’t impact on the construction or the completed structure. Throughout the process all re-compacted clay was tested to ensure density requirements were achieved. This project (combined with the Cow House site works) won a Contractors Federation, Manawatu Branch, Construction Award for projects up to $ 250,000.

Key features of the work and/or statistics:

• Investigate, design and construct to Practice Note 21, a trapezoidal shaped clay lined effluent pond. Site investigations included a full contour survey and permeability testing.
• Pond has a working capacity of 4,600m³

Key equipment used:

• Kobelco SK 210 – 20 Tonne excavator
• 7 tonne Vibrating roller
• D5 Bulldozer

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After soil testing and a complete site survey it was decided that an HDPE liner with geotextile, gas venting and safety ladders would be installed. The earthworks took 8 weeks to complete. The leak detection system was then installed and the area was made ready for the lining operation which took two days. Once the liner was installed the existing tile drains cut by the earthworks were redirected around the toe of the bank. The area was then topsoiled and grassed.

Key features of the work and/or Statistics

• Pond Sizing was determined by Fonterra.
• Blackley’s were engaged early in the project and this allowed us to investigate if the pond could be constructed using Practice Note 21 “In-Situ Clay pond criteria.
• Unfortunately the soil profile did not meet the permeability requirements.
• The pond measures 65m x 55m x 4m deep and has a working capacity of 9020m³.

Key equipment used:

• Kobelco SK 210 Excavator
• Terex Motor Scraper

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Locate various sections of the existing network to confirm pipe size and actual location.
Install 900m of 125mm & 100mm “Z” joint PVC pressure pipe for the mainlines & 880m of 50mm “Z” joint PVC pipe for the fixed in-ground sprinkler network.
Install 13 Bermad control valves & 5000m of 12mm control tube to activate the valves hydraulically.
Install 10 x 80mm K-Line irrigation hydrants and 46 fixed in ground sprinkler sockets.
Associated thrust blocks and testing all installed pipe work.

Key features of the work and/or statistics:

• Location of existing services
• Staged installation to fit in with farm operations & new factory start-up deadline.

Key equipment used:

• Ditchwitch 6510 Chain Trencher
• John Deer Tractor & Pipe Trailer
• Kobelco SK115 – 11 Tonne Excavator
• Ground Probing Radar

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The ground conditions at Ohakea are generally vey stony river run type material which can be difficult to excavate hence the wide range of equipment on the site. We also came across a large number of unknown services during the operation which kept our operators busy. And to complicate the project further the work was carried out while the runway was fully operational which meant that all excavated material had to be removed as we went and backfilling the trench had to take place as soon as possible.

Key features of the work and/or statistics:

The project involved the installation of 3300m of Megaflo 300 drainage medium complete with F2 filter material backfill
The drainage was required to stop ground water seeping under the runway.

Key equipment used:

• Marooka Backfill trucks
• Interdrain 1515 Chain Trencher
• Tractor & Trailer and a Nikkon Dump Truck
• Hired Mastenbroek Chain Rock Trencher
• Kobelco SK 80 Excavator

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Survey the new block and develop a paddock design, stock water layout and drainage design for the area. Install the stockwater pipe at 1.5m deep and then install the drainage system over the top. We also installed 374m of 450mm dia pipe along with two 4.5m deep 1200mm dia manholes so an existing open drain could be filled in. Other contractors were used to construct the open drain which required approximately 20,000m3 of earthworks.

Key features of the work and/or statistics:

Full RTK GPS survey of the site and the design of the layout. Major earthworks required for the retention drain which required Council approval.
Pipe grades and depths were designed across the whole area so that all new work would be at a suitable level for future drainage work.
Culvert under road lowered 500mm to accommodate the drainage of a low basin 1.5km away.
The installation of a 450mm pipe 5m deep, 20,000m of various sizes of land drainage pipe and 4500m of 63mm greenline water supply pipe.

Key equipment used:

• Kobelco SK210 and SK115 excavators
• Mastenbroek 2015 Chain Trencher
• Interdrain 1515 Chain trencher
• Marooka Backfill trucks
• Loaders

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The siteworks involved constructing an all weather access to the site, stripping and levelling the site, the excavation of foundations and the supply and placing of aggregate fill. We were also required to design and build a stormwater management system so that existing pipe work, when uncovered, could be adequately drained away so that it didn’t interfere with the building foundations.

Siteworks were completed on time and on budget to allow the construction of the building to meet contract timeframes.

This project (Combined with the pond construction) won a Contractors Federation, Manawatu Branch Construction Award for projects up to $250,000.

Key equipment used:
Kobelco SK210 and SK 135 excavators
Komatsu D53 Bulldozer
Compaction Rollers
RTK GPS and Nuclear Density meter
Metal Trucks

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A full site survey was conducted by Blackley Construction using our own RTK GPS. This survey included identifying ways to deal with the significant ground water issues as well as the effluent that would be deposited in the box culvert. The survey revealed that the groundwater could be drained through a sand hill into a swale drain approximately 150m away. It also revealed that the effluent could be gravity fed from the underpass to the existing effluent pond which was 700m away. The drainage and effluent pipes would be 6m deep running under the sand hill. A bench was cut through the sand hill so that a 200mm drainage pipe could be laid with a chain trencher to drain the groundwater from around the box culverts. A 200mm effluent pipe was also laid at the same time next to the drainage pipe.

Traffic management was carried out in house by Blackley Construction. With a road closure needed all affected parties were notified prior to the day when the box culvert sections were to be installed. The foundations were over excavated and the box culverts were placed on a 300mm layer of washed stone. Perforated drainage pipe was placed on each side of the culvert so that groundwater could be drained away through the new 200mm pipe. Culvert sections were placed in conjunction with Macintosh Cranes who provided the onsite cranage. Once all culvert sections were installed backfilling was carried out with stockpiled metal. This allowed Blackley Construction to have the road open that night – as required by the Traffic Management Plan. Over the following days work continued off the carriage way by fixing headwalls and the like. Once the headwalls were placed the road was then totally reinstated.

Key features of the work and/or statistics:
Telecommunication lines were relocated on both sides of the road so that phone lines remained live throughout the installation.
Final size was 3.5m x 2m x 14m
This was a Design Build project which included liaison with Local Authorities, traffic management, underground services, road reinstatement, roadside drainage, pre-cast concrete installation, QA documentation and health & safety reporting.

Key equipment used:
Hired Crane
Trucks and loaders
Kobelco SK210 & Kobelco SK135 Excavators
Sakai Roller
Topcon RTK GPS

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Portions of the main line installation were trenched with the Mastenbroek trencher for faster installation. Excavators used on other portions.