Good Engineering Practice for Northern Water and Sewer Systems

Table of Contents
PIPING
Page
2.1 INTRODUCTION...........................................................................................................................2-1
2.2 MATERIALS IN USE ....................................................................................................................2-1
2.3 ABOVE OR BELOW GRADE INSTALLATION...........................................................................2-3
2.3.1 Buried Pipes.....................................................................................................................2-3
2.3.2 Utilidor Construction.........................................................................................................2-4
2.4 PIPE MATERIAL SELECTION CRITERIA...................................................................................2-5
2.4.1 High Density Polyethylene (HDPE)..................................................................................2-6
2.4.2 Polyvinyl Chloride (PVC)..................................................................................................2-8
2.4.3 Ductile Iron (Cement Lined) .............................................................................................2-9
2.4.4 Steel (Cement Lined) .....................................................................................................2-10
2.5 UTILIDORS.................................................................................................................................2-10
2.5.1 Boxed Utilidors...............................................................................................................2-10
2.5.2 Individually Insulated Pipes............................................................................................2-11
2.5.3 Pipe ................................................................................................................................2-11
2.5.4 Pipe Support ..................................................................................................................2-11
2.5.5 Lateral Pipe Movement on Supports..............................................................................2-11
2.5.6 Thermal Expansion/Contraction.....................................................................................2-11
2.6 PIPE BEDDING ..........................................................................................................................2-11
2.6.1 Clean Sand Bedding ......................................................................................................2-13
2.6.2 Crushed Gravel ..............................................................................................................2-13
2.6.3 Screened Pit Run Gravel ...............................................................................................2-13
2.6.4 Warning Tape.................................................................................................................2-13
2.7 CONNECTIONS TO STRUCTURES..........................................................................................2-13
2.7.1 Flanges ..........................................................................................................................2-13
2.7.2 Differential Movement Connections...............................................................................2-14
2.8 FREEZE PROTECTION .............................................................................................................2-15
2.8.1 Polyurethane Pipe Installation .......................................................................................2-15
2.8.2 Electric Heat Trace.........................................................................................................2-15
2.8.3 Water Heating ................................................................................................................2-16
2.8.4 Water Circulation............................................................................................................2-16
2.8.5 Bleeding Water to Waste ...............................................................................................2-16
2.9 THAW RECOVERY ....................................................................................................................2-16
2.9.1 Sewer Manholes/Access Vaults.....................................................................................2-16
2.9.2 Sewer Access Portals ....................................................................................................2-17
2.9.3 45° Valved Nipples (50 mm) ..........................................................................................2-18
2.9.4 Pipe Draining..................................................................................................................2-18
2.9.5 Steam Thawing ..............................................................................................................2-18
2.9.6 Hot Water Thawing ........................................................................................................2-18
2.9.7 Electric Thawing.............................................................................................................2-18
GOOD ENGINEERING PRACTICE
Piping
Apr-04