Introduction

Sliplining is a trenchless rehabilitation method that inserts a new pipe inside an existing host pipe and seals the annulus to restore structural integrity, flow reliability, and service life. Hinterland Group performs sliplining in-house alongside other trenchless methods, enabling unbiased selection and integrated delivery across water, wastewater, and stormwater assets throughout the Southeast. See our Pipeline Rehabilitation and Services pages for our full PRIME offering.

Materials and where each fits

• HDPE (high-density polyethylene)

• Best for pressure and gravity pipelines when fully restrained, chemically resistant liners are desired; widely used for water, force mains, and culverts. Butt-fused strings are inserted and grouted. Reference standards include ASTM F714 (PE pipe) and ASTM F2620 (heat fusion). AWWA C906 covers PE pressure pipe commonly used for waterworks.

• FPVC (fusible PVC)

• PVC manufactured to AWWA C900 and fused for monolithic restraint, suited to pressure mains where PVC hydraulics and fittings compatibility are preferred. AWWA C605 provides underground installation and hydrotesting practices for PVC systems, including fused joints.

• FRP (fiber-reinforced polymer, “fiberglass”)

• For large-diameter gravity or pressure lines requiring high stiffness and corrosion resistance. AWWA C950 defines FRP pressure pipe classes; AWWA M45 is the primary design manual.

Diameter ranges and run lengths

• Typical sliplining diameter envelope spans 8 in to >100 in depending on liner type, access, and shape condition. Typical continuous pulls are ~300–1,000 LF; segmental sliplining is often 100–300 LF. Selection is governed by access constraints, host alignment, and insertion loads.

Gravity vs pressure applications

• Gravity sewers and storm drains

• Objectives: restore structure, reduce infiltration/exfiltration, and stabilize soils with annular grout. Assess hydraulic impacts from reduced cross-section and mitigate (e.g., inlet improvements) where required.

• Service reconnections: laterals are commonly reconnected by localized excavation and saddle fittings; robotic cutters can assist with trimming tie-ins and obstructions. Post-install CCTV is performed to PACP standards.

• Pressure mains (water, reclaimed, force mains)

• Objectives: regain pressure rating and surge tolerance with restrained liner systems and suitable appurtenances. Hydrostatic testing follows material-specific standards (e.g., AWWA C605 for PVC systems; FRP per C950). Services are typically reconnected using external taps/tapping sleeves and restrained saddles; interior robotic reinstatement is not used on pressure pipe.

Annular space grouting (why, what, how)

• Purpose: eliminate infiltration paths, prevent liner flotation and point loading, and transfer loads uniformly to the host. Grout also seals terminations at manholes/structures.

• Mixes: low-density cellular or cementitious grouts are typical; select for pumpability, shrinkage control, and heat of hydration compatible with liner. Controlled low-strength material (CLSM) is common for segmental FRP/PVC applications.

• Execution: place grout in lifts, maintain balanced pressures, and monitor liner ovality and flotation. Ensure full encapsulation to avoid bearing at the invert. Terminations receive water-tight bulkheads/band seals before grouting.

Robotic reinstatement and service reconnections

• Gravity pipelines: laterals after sliplining are usually reconnected by excavation and mechanical saddles. Robotic cutters are useful to trim ends at manholes, remove intrusions, and prepare tie-ins. Where CIPP is selected instead of sliplining, robotic lateral reinstatement from within the pipe is standard practice (Hinterland performs both methods; see Inspection).

• Pressure mains: services are reconnected by external taps/tapping sleeves and restrained saddles; do not use internal robots for pressure services. Follow material-specific tapping and pressure test procedures per AWWA standards.

QA/QC and acceptance testing

• Pre-construction

• Cleaning and PACP-coded CCTV to document condition, verify clearances, and identify obstructions.

• Survey of bends/ovality, service inventory, and bypass requirements.

• Production controls

• Fusion QA: record heat/fusion parameters and bead quality for HDPE (ASTM F2620) and FPVC; maintain heat/fusion logs and operator qualifications.

• Liner handling: verify stringing length vs. insertion loads; perform test pulls where warranted.

• Grouting QA: log mix design, density/flow, grout volumes, lift sequence, pressures, and liner deflection checks during placement.

• Post-construction

• Hydrostatic testing per material standard (e.g., PVC systems per AWWA C605; FRP per AWWA C950 as applicable).

• PACP/LACP post-CCTV for gravity systems, service verification, and final acceptance documentation (as-builts, test records, fusion/grout logs).

Representative project snapshots (Florida/Georgia)

• Coastal Florida storm system: large-diameter CMP outfall stabilized with FRP segmental slipliner and cellular annular grout to control infiltration and tidal surcharge. Work sequenced around tides with bypass and staged grouting to manage flotation risk.

• Central Florida force main: HDPE sliplining of aged PCCP to restore pressure service; fused strings installed from limited access pits, followed by hydrotest and hot taps for service reconnections.

• Georgia culvert rehabilitation: degraded RCP under roadway sliplined with FPVC to balance constructability and hydraulics; inlet improvements offset cross-section loss and maintained design flows. Night work minimized traffic impacts.

Note: Snapshots illustrate common regional conditions and method selections. Hinterland evaluates each asset and may recommend CIPP, pipe bursting, geopolymer spincast, or open-cut replacement when sliplining is not optimal. See Pipeline Rehabilitation and Evaluation & Assessment.

Quick selector: sliplining materials at a glance

Liner material	Typical use cases	Joining method	Typical diameter envelope	Core references
HDPE	Water, force mains, gravity sewers, culverts; long continuous pulls	Butt fusion of PE per established parameters	Commonly 8–65 in for waterworks; gravity/culvert sliplining up to >100 in, project-dependent	ASTM F714 (PE pipe), ASTM F2620 (fusion), AWWA C906 (PE pressure pipe)
FPVC (fused PVC)	Water and pressure sewer mains where PVC hydraulics/appurtenances are preferred	Butt fusion process for PVC; PVC appurtenances	4–60 in nominal classes per AWWA C900; project-dependent in sliplining	AWWA C900 (PVC pressure pipe), AWWA C605 (PVC installation/hydrotest)
FRP (fiberglass)	Large-diameter gravity or pressure lines; high stiffness/corrosion resistance	Gasketed bell/spigot or adhesive joinery	1–156 in pressure classes defined; segmental for very large gravity	AWWA C950 (FRP pressure pipe), AWWA M45 (design manual)

Owner inputs that accelerate design and pricing

• Pipe inventory: host material, diameter(s), wall/section loss, bends, access points, and surface constraints.

• Hydraulics: design flows/levels, headroom for cross-section changes, and allowable energy grade impacts.

• Connections: count and type of laterals/services and reconnection preferences.

• Testing/acceptance: desired hydrotest criteria, CCTV deliverables (PACP/LACP), and documentation standards.

Standards and technical references (non-exhaustive)

• Sliplining selection, methods, and reinstatement: AWWA Manual M28, Rehabilitation of Water Mains (Ch. 8 Sliplining; Ch. 11 Service Laterals).

• HDPE liner pipe: ASTM F714 (PE pipe); ASTM F2620 (heat fusion). Waterworks PE: AWWA C906.

• PVC systems: AWWA C900 (PVC pressure pipe); AWWA C605 (underground installation and hydrotesting, including fused joints).

• FRP systems: AWWA C950 (Fiberglass Pressure Pipe) and AWWA M45 (Fiberglass Pipe Design).

• Gravity pipeline inspection/QC: NASSCO PACP/LACP for pre/post CCTV deliverables.

• Annular grouting practice: DOT and research guidance for full encapsulation and CLSM/cellular grout usage; evaluate density, lift sequencing, and bearing control for each project.

Why Hinterland Group for sliplining

• All trenchless technologies performed in-house, enabling method-neutral recommendations and single-source accountability.

• Integrated CCTV inspection, bypass, electrical, and emergency response capabilities across the Southeast.

• Regional deployment from Florida and the Carolinas supports rapid mobilization for planned work and emergencies. Explore Services, Maintenance Plans, and Inspection.