Introduction

Sliplining is a trenchless rehabilitation and replacement method that installs a new carrier pipe inside an existing host pipe to restore structural integrity, hydraulic performance, and service reliability with minimal surface disruption. Hinterland Group evaluates sliplining alongside other in‑house trenchless options to select the most cost‑effective, least disruptive solution for each asset. See our end‑to‑end trenchless capabilities on the Pipe Rehabilitation and Services pages.

Southeast Coverage (Florida‑First)

We mobilize quickly across: Florida (FL), Georgia (GA), South Carolina (SC), North Carolina (NC), Alabama (AL), Tennessee (TN), Louisiana (LA), and Texas (TX).

Callout: Hydrostatic Test Workflow For pressure mains, our sliplining program follows a disciplined hydrostatic test—pre‑checks, de‑air, soak/stabilize, pressurize, hold/measure, acceptance, and safe de‑pressurization. See the full step‑by‑step process below.

See sliplining and complementary trenchless work in action:

Gravity/stormwater: Charlotte County Stormwater Collection Rehabilitation
Pressure/force main: Fort Pierce Utilities Authority (FPUA) Force Main

See Sliplining on the Main Site →

When Sliplining Is The Right Choice

Host pipe has moderate to severe defects (corrosion, joint offsets, infiltration) but maintains a generally continuous alignment and sufficient internal clearance for insertion.
Capacity loss from a reduced diameter is acceptable, or mitigated by improved roughness and localized upsizing where feasible.
Open‑cut replacement is infeasible due to depth, utilities, traffic, environmental constraints, or schedule.
The asset is a pressure main needing a new, leak‑tight pressure class pipe, or a gravity line needing a structurally sound, corrosion‑resistant liner installed with annular grouting.

Compare with our other methods if alignment change or upsizing is required: pipe bursting, CIPP, geopolymer spincast.

Systems Served: Pressure and Gravity

Pressure mains: potable water transmission/distribution, reclaimed water, and force mains. Design focuses on pressure class, surge, restrained joints, and a validated hydrostatic test, followed by disinfection when applicable. See complementary construction and bypass capabilities under Repair & Replacement.
Gravity conveyance: sanitary sewer, stormwater, culverts, and special structures. Design focuses on long‑term structural capacity, corrosion protection, abrasion resistance, and robust annular grouting to eliminate groundwater paths. See Inspection and Maintenance for cleaning and CCTV workflows.

Materials We Install (Project‑Driven Selection)

Hinterland performs all trenchless technologies in‑house, enabling objective material selection per site constraints, hydraulics, and lifecycle cost. Learn more.

HDPE (High‑Density Polyethylene)

Typical use: pressure or gravity; fused joints create a fully restrained, leak‑tight system.
Advantages: excellent corrosion/chemical resistance; flexibility for insertion through bends of the host; long, continuous pulls reduce number of pits.
Considerations: SDR selection for pressure class and buckling under external loads; thermal contraction/expansion management; pulling loads and insertion logistics.

FRP (Fiberglass‑Reinforced Polymer)

Typical use: gravity or pressure where high stiffness/strength and corrosion resistance are required, including large diameters and long spans.
Advantages: high structural stiffness at lower wall thickness; customizable layups for gravity/pressure classes; smooth interior for favorable hydraulics.
Considerations: segment joining (gasketed or laminated joints); handling/laydown planning; ovality tolerance and annular grout pressures.

PVC (Polyvinyl Chloride)

Typical use: pressure (gasketed restrained systems) and gravity (gasketed gravity pipe) where rigidity, smoothness, and well‑defined standards/pressure classes are desired.
Advantages: predictable pressure ratings; excellent interior smoothness; broad availability.
Considerations: joint restraint strategy for pressure mains; insertion clearances and bell‑to‑spigot transitions; thermal and handling limits.

Annular Grouting: Objectives and Execution

Proper annular grouting locks the carrier pipe structurally, eliminates groundwater flow paths, and prevents flotation or ovalization.

Mix selection: flowable, low‑shrink cementitious or cellular grout tailored to span, cover depth, groundwater head, and host condition. Strength and density are specified to meet structural needs while limiting buoyant uplift on the carrier pipe.
Sequencing: install bulkheads and vents; pump from low points to high points; stage lifts to control pressure at the crown and to avoid carrier deformation. Monitor injection pressure continuously.
Port layout: grout ports and vents at engineered intervals (e.g., at pits, manholes, and intermediate stations) based on reach length and host geometry to ensure complete fill and air relief.
Controls and QA: record batch data, temperature, density/flow checks, start/stop times, injected volumes by port, and line pressures. Verify complete fill via CCTV/visuals at accessible points and vent returns.
End seals and water‑stops: install end seals at structures and service interfaces to resist infiltration/exfiltration and protect the annulus; detail transitions to manholes, structures, or fittings.

Hydrostatic Testing Workflow (Pressure Mains)

Hinterland’s pressure‑main sliplining program executes a disciplined hydrostatic test to validate pipe integrity and joints. Acceptance criteria, pressures, and durations follow the project specifications and applicable AWWA/municipal standards. 1) Pre‑test checks: confirm installation records, appurtenances isolation, thrust/anchor restraints, and temporary caps or test bulkheads. Verify all air release points are accessible. 2) Pre‑fill and de‑air: fill the test section slowly from the low point; cycle air release valves at high points until a continuous water column is verified. 3) Stabilization/soak: hold at a preliminary pressure (or ambient full water condition) to allow temperature and pipe expansion stabilization per specification. 4) Pressurization: raise to the specified test pressure (often a multiple of operating pressure, capped by pipe/fitment limits). Record pressure and temperature at defined intervals. 5) Test period: maintain pressure for the specified duration; measure makeup water added (if any) to sustain test pressure. Log ambient and water temperatures. 6) Acceptance: compare measured makeup water/leakage to allowable criteria in the contract documents. No visible leakage at appurtenances or test assemblies. 7) Post‑test: depressurize safely; remove temporary assemblies; complete disinfection and flushing for potable systems as specified; compile a signed test report with calibrated gauge and data logger records.

Access, Bypass, and Traffic Management

Access pits: size and spacing designed for carrier length, fusion/assembly method, and host obstructions; locations coordinated to avoid critical utilities and maintain traffic.
Bypass pumping: for sewers/force mains, design, install, and monitor a right‑sized bypass with redundancy and telemetry per flow metering and contingency plans. See Repair & Replacement and Maintenance for in‑house bypass capabilities.
Surface impacts: phased MOT plans, night/weekend work windows, and restoration plans minimize disruption in business districts, neighborhoods, and corridors.

Diameter Envelope and Typical Applications

The optimal sliplining size is project‑specific (host condition, hydraulics, clearances, and available carrier sizes). Hinterland routinely evaluates small to large conveyance assets and delivers custom solutions when needed.

Carrier material	Typical applications	Common host diameter range we evaluate	Notes
HDPE	Pressure mains, force mains, gravity	~6–72 in	Long fused pulls; fully restrained joints; excellent corrosion resistance.
FRP	Large gravity lines, culverts; select pressure	~24–96 in+	High stiffness; segmental install; engineered joints; well‑suited for large diameters.
PVC	Pressure and gravity (gasketed)	~6–48 in	Widely available pressure classes; restrained joint options for pressure service.

Ranges above are typical evaluation bands; final selections depend on structural/hydraulic modeling, host geometry, market availability, and project specifications documented during Evaluation & Assessment.

QA/QC and Closeout Package

Pre‑construction: cleaning and CCTV inspection, survey, and constructability review; baseline videos/reports.
Production records: fusion/weld or joint logs, pulling loads (if monitored), annular grout batch/pressure/volume logs, insertion and staging documentation.
Testing and commissioning: hydrostatic test reports (pressure mains), disinfection/flushing records for potable mains, final CCTV for gravity systems.
Deliverables: as‑builts, redlines, GIS data (if requested), O&M guidance, and recommended preventive Maintenance Plans.

States We Serve for Sliplining

We mobilize across the Southeast from our Florida HQ and regional resources, providing rapid response and program delivery in:

Florida (FL)
Georgia (GA)
South Carolina (SC)
North Carolina (NC)
Alabama (AL)
Tennessee (TN)
Louisiana (LA)
Texas (TX)

See our regional coverage and markets on Markets We Serve.

Why Hinterland for Sliplining

Complete trenchless portfolio in‑house for unbiased method selection and single‑source accountability. Pipe Rehabilitation
Integrated services: inspection, bypass, electrical, lift station, and restoration to keep systems online during construction. Services
24/7 emergency readiness and large‑fleet mobilization to protect communities and operations. Maintenance
Safety‑first culture and documented project controls that reduce risk and ensure predictable outcomes. About

Request a Sliplining Assessment

Ready to evaluate sliplining for a pressure main or gravity line? Hinterland’s team will review inspection data, model hydraulics, define material/grout solutions, and deliver a construction plan and schedule. Contact us to start your assessment: Contact Us.

Sliplining (Pressure & Gravity) — Southeast