Rafael Ortega, PE at LAN, discusses design issues, ROW concerns, technical specifications, and critical installation and constructability of large diameter water transmission lines.
10. Geotech Investigation
Soil conditions vary along alignment
Determine limits of soil variations
Subsurface conditions impact:
Sb f diti i t
– Long-term performance of pipeline
Long-
– Specifications
– Tunneling criteria
– Construction claims
11. Traffic Control
Key to project acceptance by stake holders
The more detailed the less disruption
Optimize h i
O ti i phasing:
– Minimize duration of impacts
– Provide for progressive transitions
14. Route Evaluation Factors
Limits of City jurisdiction
ROW Acquisition
Distinct Neighborhoods
Di ti t N i hb h d
Type of Construction Environment
–DDevelopment type
l
– Contamination
20. Rigid vs. Flexible
g
Width of Trench
– Practical Space Required
– Larger Pipe = Larger Width
All Pipe Not Created Equal
21. All Pipe Not Created Equal
p q
Made to Order
Material
Mt il
Properties
– less fo gi ing
forgiving
Design
Considerations
22. Nonmetallic Materials
PVC, FRP, HDPE
PVC FRP
Speed of installation
Alternatives in stray current areas
Alt ti it t
Steel or DIP bends and outlets
–V l
Valves, fittings, and outlets
fi i d l
– Vertical and horizontal
25. Pipe Comparison Summary
Gasket
Field Joint
Pipe Corrosion Modifications Field Welding Bonding
Pipe Material Design Joint Type Protection Allowed? Allowed? Req’d?
Ductile Iron
D til I R/F G Y Y N Y
Steel F G or W Y Y Y Y or N
FRP F G or W N Y N N
Fused/
HDPE F Flanged N Y Y N
PCCP R G or W Y N Y Y or N
Bar Wrapped F G or W Y N Y Y or N
F = Flexible R = Rigid G = Gasket W = Welded Y = Yes N = No
27. Challenges During Construction
Pipe material availability
Private utility relocations
Competition for contractor’s
resources
Construction phased to
C t ti h dt
avoid impacting operations
28. Construction Issues
Verify densities of pipe bedding
Lay pipe continuously
Do t
D not remove stulls prior to backfill
t ll i t b kfill
Perform internal inspections during construction
29. Bedding Requirements
g q
Pipe Embedment
– Bottom shaping
– Compaction at haunches
Movement of trench support
Use of special embedment material (depth)
Trench dams
30. Backfill Critical
Effectiveness of compaction critical
– Loading capability
– Deflection affects coating and linings
E’ = Modulus of Soil
– % Compaction
– Type of Soil
– Greatest Affect on Wall Thickness
35. Butt Strap
Butt-Strap
Closure Piece
Cl Pi Poorly Grouted
P l G td
36. Exterior Joint Grout
Diaper;
– w/ ethafoam backing
– Width
Installation
– Grout mix and testing
– Bottom joint recess (similar to bell form)
– Rod and set time required
q
38. Annular Space Issues
p
Flotation of Pipe
Grouting Monitoring
– M it i key
Monitoring k
– Pressure and volume
– Potential exists w/ low-density grout
low-
40. Testing of Line
Impacted by potential contamination from
existing section
Water discharge receptors
– Capacity
– Locations
Schedule considerations
– Fill rates
– Required interconnects – temporary and permanent
41. Unavoidable Change Orders
Debris encountered in excavations
Longer work duration
Unanticipated services
U ti i t d i
– Active
– abandoned