Underground PipelinesModule #8

Prepared by

Dr. Randy R. RappJuly 2005

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Installation Methods

• Trenching and backfilling (cut and cover)– Traditional– Bedding can be critical

• Pipe jacking• Horizontal directional drilling• Slip lining• Pipe bursting

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Horizontal Directional Drill

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HDD Reception Pit

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Plastic Pipe

• PVC, PE, HDPE• Protect joints

– Solvents, thermal (PE, HDPE), or threads– Snaking– Bedding and backfilling– Flotation– No blocking– Expansion loops or joints– Supports

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Vitreous Clay Pipe (VCP)

• National Clay Pipe Institute standards, p. 183; Table 8-2

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Concrete Pipe

• Unreinforced• RCP, Reinforced Concrete Pipe

– Reinforcement patterns– Inspection and preparation– Laying and jointing– Bedding and backfill

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RCCP (Reinforced Concrete Cylinder Pipe) and ML&C (Mortar-Lined and

Coated Steel Pipe)

• Delivery, storage and handling• Excavation and bedding• Lifting and positioning• Jointing• Backfilling and compaction

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Trenches

• Sheeting• Subsidence• Specifications• Backfilling

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Payment

• Station lengths, if specified• Otherwise, slope length

– Length placed before cutting, rounded up to nearest 2-ft increment

– If centerline is skewed, use longer side– Include any “formed out” distance