international
construction
may 2014
42
Intelligent tools
UTILITES
various spraymethods. Somuch so that even the leading spray
companies are now starting their own departments that only
workwith lining.”
He said housing associations, property owners, property
managers and construction companies were coming to
understand the benefits of renovating sewer systems without
open cut construction.
“When the methods and materials are reliable and the end
result is the same as a traditional pipe replacement, we see that
>
evenmore people choose lining instead of breaking up property
to replace old leaky pipes.”
Trenching
However, those on the trenching side of the underground
utilitiesmarket would likely argue that theirmethod is themost
popular. In any case, if the job requires the ground tobe opened
up, it presents contractors with an entirely different array of
challenges.
Indeed, National Trench Safety said trench shields were
evolving as contractors moved more and more towards using
lightweight excavationmachinery to dig trenches.
Joe Turner, director of engineering, said, “The change in
excavation technology is strongly related to the advancement
of smaller, lightweight equipment for excavations inmid depth
utilitywork.
“Large, heavydown anddeep excavators tear up streets, require
S
cottishWater required the replacement of a60m length of 300mmdiameter sewer
witha600mmdiameter pipe inEdinburgh, UK– a job that presenteda challenge to
contractor PipelineDrillers.
Various optionswere considered, including open cut, horizontal directional drilling (HDD),
standardpipebursting andauger boring. But all were rejecteddue to a range of factors
including the limited siteaccess and the risk of local disruptionandenvironmental damage.
A combined auger boring rig andpipeburst rigassemblywas selected for the task– at one
side of the run,where the existingpipe ranat 3.5mdeep, aPerforator PBA150 auger boring
systemwith150 tonnes of thrustwas used. At the reception end of the run, aHammerhead
100 tonne capacityHB100pipebursting rigwas positioned, providedbyUMole.
A series of pulling rodswerepassed through theexistingpipe to connect themachines.
Working together toprovideup to250 tonnes of forceat thepipe eatinghead, thePerforator
unit jacked the assembly head forwardwhileat the same time theburster rigpulled the
assembly towards its operatingpit.
Not only did this provide sufficient thrust to theburstinghead to fracture the oldpipe, but
also enoughpressure toensure thenewpipepassed into thegroundeffectively. At the same
time, thedisplacedearthand fragments of thebrokenpipewere transferredbackdown a steel
sleeveby the auger spiral, and removed to the surfaceby skips from the jackingpit.
A600mmdiameter sewer pipewas inserted through the sleevepipe and connectedat
either end to the remainder of the sewer network. Theduration of theworks totalled two
weeks.
Peter Taylor,managingdirector of PipelineDrillers, said, “Thiswas not an easy project by
anymeans. The logistics bordered onnightmarishwith limits on equipment size, site storage,
transportation andprecise timing. However, our crewworked extremelywell with [lead
contractor] George Leslie’sworkforce to safely andefficiently completewhatwas something of
auniqueproject under challenging circumstances in an excellent timeframe.”
Lateral thinking
A pipe bursting system came into its own on a sewer project
DitchWitch’s new JT60 and JT60 all-terrain HDD rigs come
factory-equippedwith GPS technology for fleet tracking and
remote viewing of machine data.
Vermeer’s new Tier 4 Final-compliant D9x13 S3 Navigator
HDD rig is the first of the S3 generation of drills, and
has been designed for installation of utilities such as
communication, power, gas andwater, aswell as some
limited sewer applications.
