A slideshow detailing the Engineering aspects of the Cascade Dam HDD

1. Priority Sewerage Program
Upper Blue Mountains Sewerage Scheme
Horizontal Directional Drilling
Author: Dean Garratt

2. GOALS & BACKGROUND
PSP Alliance
Environmentally sensitive
engineering
• PSP alliance aims to improve public health and
protect the environment especially local
waterways and catchments
• Upper Blue Mountains project introduces
reticulated sewerage to replace poorly
performing septic tanks
Major Sydney Water catchment area
World Heritage Area (We are boring under Cascade Creek pictured in the
background)

3. PROJECT SCOPE & ISSUES
• Connect the new sewerage network to the Winmalee sewerage treatment plant.
• Use Horizontal Directional Drilling to bore from Meadow Bath to the existing North Katoomba sewer
through Sandstone, Claystone and minor seams of Ironstone.
• Perform geological survey and detailed design analysis to minimise risk and maximise design life
• Use trenchless technology (HDD) to minimise the impact on the environment.
– This is particularly important due to the World heritage status and tourism of the region.
– HDD allows precise control of the grade so pumping stations
aren’t needed, eliminating capital, running and maintenance costs.
• Install 2 pipelines: 2366m @ DN450mm and 2358m @ DN225mm.
• The smaller pipe will be used as backup in case of blockage or overload.
• Use Heavy Duty Polyethylene (HDPE) pipe to maximise design life
and ease of installation.

4. HOME
Technical Specification
CostsPlans Productivity
End Show
The HDD Process
Achievements
HOME PAGE
Site Layout
Pipe Welding
Pipe Installation
Schedule

5. HomeThe geographical layout showing location of
pipes and Cascade Dam
Section DN225 Section DN450
PLANS – Plan View

6. Home
Home
PLANS – DN225 Section
Plan View Section DN450

7. Home
PLANS – DN450 Section
Plan View Section DN225

8. Home
• The HDD for the DN255 was carried out first
• The rig was then moved to the DN450 location & 225mm
pilot hole was drilled
• The hole was then forward reamed to 450mm diameter
• After drilling was complete, the pipes were installed into the bores
• The pipes were welded in parallel with the drilling so that they
could be installed into their bores as soon as drilling was complete
Summary Schedule

9. Site Layout
Home

10. • A detailed geotechnical survey helps make the right
choice of drilling rig, fluid composition, tools and
techniques
• Drill path is engineered using computer-aided design
and sophisticated mechanical and stress engineering
software
• With the rig accurately aligned to the drill path, drilling
fluid (bentonite & water) is pumped down the drill pipes.
This provides high pressure fluid to jet nozzles for drilling
the softer materials, or power to a down hole motor
which drives a roller-cone bit in rock.
• The fluid provides drilling power, consolidates the walls
of the drillhole, acts as a lubricant and carries spoil out
of the hole
• As the cuttings laden fluid travels back up the drillhole, it
is captured, the cuttings removed and recycled, so the
fluid can be pumped back around the drilling loop
• The downhole drilling assembly is guided by electronic
steering instrumentation that transmits data in real time
to a surface-based computer that allows the driller to
precisely locate the drilling assembly and guide it along
the pre-determined drill path
• The drilling assembly is replaced with a reamer which is
pulled back or pushed forward to enlarge the pilot hole
to the size needed for the product pipe
HDD Process Home

11. Technical
Spec
The American Augers DD-1100: DD1100 Spec. link
Home
Engine Type:
2 x Caterpillar 3412E DITTA diesel engines.
Rating:
2 x 760 HP @ 2100 RPM = 1520 total HP
Pumps:
Each engine drives 4 hydrostatic drive pumps – 2 for rotary
torque and 2 for thrust/pullback
Rotary System:
Four pinion drives
100,000 ft-lbs rotary torque @ 0-40 RPM (at max torque)
44,000 ft-lbs rotary torque @ 0-90 RPM (at max speed)
Carriage System:
Six pinion drive, each with a planetary gearbox and two
speed radial motor. Two 3” mud hoses in a hose carrier.
Carriage Thrust/Pullback:
500 tonnes @ 6.9m/min
372 tonnes @ 9.2m/min
241 tonnes @ 13.8m/min
114 tonnes @ 32.5 m/min
Operators Control Console Description:
Electric over hydraulic controls, pulse with modulation,
Diagnostic warning lights for all filters & fluid levels. Full
digital and analogue instrumentation.
Other Features:
Wire-line steering system, 3785 LPM flow capacity, Wiggle
steer

12. Home
• The pipeline was joined using industry
standard butt fusion welding
• Due to access restrictions, the pipeline was
welded & debeaded in 800m lengths. Each
length of pipe was 12m.
• The welding machine used was a McElroy
TracStar No. 618 Fusion welder
• Welding the DN225 pipe achieved
approximately 5-7 joints/day
• Welding the DN450 pipe achieved
approximately 3-5 joints /day
• To see an animation of the butt fusion welding
process, click on the link below
Fusion welding animation
HDPE Pipe welding

13. Home
•The pilot hole was drilled short of tunnel. The bentonite in the borehole
was cleaned via flocculation. Once the drilling mud is cleaned the last
section of the borehole will be drilled with clean water and punch into the
tunnel
•The pipes were pushed/floated in from entry side (rig site, Medlow Bath)
towards the exit side (Katoomba)
•A 30 tonne excavator was used straddle the entry point and feed the
pipe directly into the hole with additional excavators used to help manage
the bends in the pipe string
•The pipe was fed into the bore open ended to allow fluid remaining in the
belly of the bore to flow into the pipe thus insuring the pipe is not too
buoyant which would jam the pipe against the top of the hole
• The designers generated 31 variations of what installation loads may be
seen when installing the pipe, they took into account the following criteria;
-Mud Weight
-Viscosity
-Helical Buckling
-Sinusoidal Buckling
-Asbuilt profile of the bore.
-Properties of the HDPE pipe
HDPE Pipe Installation

14. Production & Productivity - Overview
Home
• Productivity was increased by using
parallel processes
• Drilling operations were carried out 24/7 to
decrease the overall duration thus
minimising overhead costs
• On average approximately 10-15 men
were used during the peak day operating
period & 6-8 men used during the night shift
to save on cost
• The plant and equipment chosen was
advanced enough to complete the work with
a high factor of safety.
DN225 Pilot hole for DN450 pipe
DN225 Drilling

15. Production & Productivity – DN225 Drilling
Average production = 2.2 manhours / metre
Home
Overview DN225 Pilot hole for DN450 pipe
Average productivity = 76 metres / day

16. Production & Productivity – DN225 Pilot hole Drilling for DN450 pipe
Overview DN225 Drilling
Average production = 2.0 manhours / metre
Home
Average productivity = 126 metres / day

17. • Total Cost incl indirects = $14.4 million
• Total Cost directs only = $10.3 million
• Total length of 2 bores = 4724m
• Rate incl indirects = $3050/metre
• Rate directs only = $2180/metre
Cost
Home

18. Technical feats and
achievements
At 2.4km length, this is the world's
longest HDD sewer installation,
overtaking the record set by AJ Lucas
with the Wollongong sewer pipeline
installed in 2004.
Home

19. End of presentation