Sewer Lining For Storm Water Pipes: Methods, Costs, And Practical Considerations

When storm water pipes fail, you usually find out the hard way: flooding where it’s never flooded before, sinkholes that appear out of nowhere, or rapidly deteriorating pavement and landscaping. The problem is urgent, but ripping everything up to replace buried storm lines is expensive, disruptive, and often unnecessary.

That’s where sewer lining for storm water pipes comes in. Modern trenchless lining lets you structurally rehabilitate aging storm drains from the inside, restoring capacity and extending service life, often at a fraction of the cost of open-cut replacement and with far less disruption.

In this guide, you’ll learn how storm water pipe lining works, the technologies available, key engineering and cost considerations, and what it takes to plan a successful project. Whether you manage residential, commercial, or municipal systems, this will help you decide when lining is the right move, and how to do it right.

NuFlow is a leading trenchless pipe repair and rehabilitation company serving residential, commercial, and municipal properties. If you’re already dealing with flooding, erosion, or suspected storm line failures, you can get expert help or request a free consultation through our plumbing problems page.

Understanding Storm Water Pipe Problems And Why Lining Is Used

Common Issues In Storm Water Systems

Storm water systems work hard and get very little maintenance attention until something goes wrong. Over time, you’re likely to see:

• Corrosion and material loss – Especially in corrugated metal pipe (CMP) and reinforced concrete pipe (RCP). Constant wet/dry cycles, road salts, dissolved oxygen, and chemicals in runoff can eat away at the pipe wall.
• Joint separation and offset joints – Ground movement, poor bedding, and traffic loading can separate joints, leading to leaks, soil loss, and inflow/infiltration.
• Cracks, fractures, and breaks – Age, heavy loads, or shallow cover can cause longitudinal and circumferential cracking. In plastic pipes, you may see deformation or buckling.
• Root intrusion – In some systems (especially combined or older systems near vegetation), roots follow moisture into joints and cracks, restricting flow.
• Sediment buildup and debris – Imperfect slopes, rough interiors, and structural defects trap silt, leaves, and trash, which reduce hydraulic capacity.
• Infiltration and exfiltration – Groundwater entering the system (infiltration) and storm flows leaking out (exfiltration) both cause problems: surcharging, soil loss, sinkholes, and pavement failures.

Because storm water pipes are often large-diameter and buried under roads, parking lots, or critical infrastructure, addressing these issues with excavation alone can be extremely costly.

How Storm Water Pipe Failures Impact Properties And Infrastructure

Storm system defects aren’t just an underground nuisance, they quickly become surface-level problems that you can’t ignore:

• Surface flooding and backups – Reduced hydraulic capacity from debris, deformation, or collapsing pipes can cause localized flooding during moderate storms, not just extreme events.
• Sinkholes and voids – Exfiltration washes fines out from around the pipe. Over time, this creates voids that collapse, forming sinkholes in yards, pavements, or roadways.
• Pavement and foundation damage – Settlement and loss of subgrade support lead to cracked asphalt, sidewalk heaving, and even structure foundation issues near failed lines.
• Environmental damage – Exfiltrating storm flows can erode adjacent slopes and streambanks, while infiltration can overload downstream systems and treatment facilities.
• Regulatory and liability exposure – For municipalities, HOAs, and commercial owners, recurring flooding or visible sinkholes increase risk of claims, code violations, and regulatory scrutiny.

Because storm systems are designed around expected flow rates and levels of service, any reduction in capacity or structural integrity undermines your entire drainage strategy.

When Sewer Lining Is A Better Option Than Pipe Replacement

Open-cut replacement still has its place, especially where:

• Existing pipe is severely collapsed beyond cleaning
• Lines are very shallow and easily accessible
• Grades must be redesigned or realigned

But, sewer lining for storm water pipes is often the better option when:

• The pipe is structurally compromised but still mostly intact – Cracked, corroded, or jointed pipes that maintain a continuous path are ideal for lining.
• Surface disruption must be minimized – Under roads, driveways, landscaped areas, buildings, or sensitive habitats, trenchless methods avoid extensive excavation.
• You need faster turnaround – Lining projects can often be completed in 1–2 days per reach, rather than weeks of traffic control and restoration.
• Budget is constrained – Trenchless methods typically cost 30–50% less than full dig-and-replace once you factor in restoration, traffic control, utility relocations, and business interruption.
• Access is limited – Where you can only get to the system through manholes, catch basins, or small excavations, lining lets you work from existing access points.

As trenchless technology leaders, NuFlow specializes in CIPP lining, epoxy coating, and UV-cured pipe rehabilitation with minimal property disruption. If you’re comparing options, sewer lining is the solution you should at least evaluate before committing to full replacement, especially for large-diameter storm drains beneath valuable improvements.

How Sewer Lining For Storm Water Pipes Works

Overview Of Trenchless Pipe Rehabilitation

Trenchless rehabilitation is essentially “surgery from the inside” for your storm water system. Instead of digging up and replacing the pipe, you:

1. Access the pipe through manholes, catch basins, or small pits.
2. Clean and prep the interior.
3. Install a new structural or semi-structural liner inside the old pipe.
4. Cure or set the liner so it becomes a tight-fitting new pipe.

The host pipe becomes a form and load-sharing structure for the new liner. Done correctly, you end up with a smooth, corrosion-resistant pipe-within-a-pipe designed to last 50+ years.

Step-By-Step Sewer Lining Process For Storm Drains

Most storm water lining projects follow a similar sequence (details vary by technology):

1. Site setup and traffic control – Crews stage equipment near access points, set up safety barriers, and establish any required lane closures or detours.
2. Initial CCTV inspection – A camera is run through the storm line to document defects, confirm dimensions, and identify laterals, inlets, and structural risks.
3. Cleaning and debris removal – High-pressure water jetting, mechanical cutters, or descaling tools remove roots, corrosion, loose concrete, sediment, and debris.
4. Final pre-lining assessment – A follow-up CCTV verifies that the pipe is clean enough for lining and that there are no blockages or severe collapses that would prevent liner insertion.
5. Liner installation – Depending on the method, this may involve:

• Inverting a resin-impregnated tube with water or air (CIPP)
• Pulling a liner into place and inflating it
• Spin-casting or spraying a lining material onto the walls
• Pulling in a sliplining pipe or segmental lining panels

1. Curing or setting – For CIPP and many polymeric liners, heat, steam, hot water, UV light, or ambient cure is used to harden the liner.
2. Reinstatement of inlets/laterals – Robotic cutters reopen catch basin inlets, lateral connections, or outfalls that the liner covered.
3. Final CCTV and testing – The rehabilitated pipe is inspected and, where specified, tested for leakage, thickness, and structural performance.

NuFlow’s epoxy and CIPP systems are engineered to be installed quickly, with most individual segments rehabilitated in one to two days, minimizing flooding risk and disruptions.

Pre-Inspection And Cleaning Requirements

Storm water systems are often dirtier and more irregular than sanitary sewers, so proper preparation is critical:

• CCTV mapping and condition grading – You should know pipe sizes, materials, lengths, inverts, and key defects before choosing a lining method.
• Thorough cleaning – Sediment, rocks, and organic debris must be removed. In corroded concrete or CMP, loose material should be descaled so the liner bonds or fits correctly.
• Bypass or flow management – Even though storm lines are usually dry-weather systems, you need a plan for handling rainfall during construction. This may include temporary plugs, pumps, or scheduling around weather.
• Structural evaluation – An engineer should confirm that the host pipe still has enough integrity to support lining and the surrounding soil loads.

Cutting corners here often leads to liner irregularities, wrinkles, or incomplete curing. A high-quality pre-inspection and cleaning program is one of the best investments you can make in the success of the project.

Curing, Final Inspection, And Return To Service

Once the liner is in place:

• Curing – With CIPP, curing might be done with hot water, steam, or UV light. With epoxy spray systems, cure times are typically faster but still must be verified. Cementitious linings hydrate over time and may require controlled moisture or curing agents.
• Cool-down and depressurization – After curing, the liner is cooled (if heated) and internal pressure is released. The liner shrinks slightly to form a tight fit against the host pipe.
• Cutting inlets and laterals – Robotic cutters or trained technicians reopen storm inlets, junctions, and laterals, restoring system connectivity.
• Final CCTV inspection – A detailed video log documents installation quality, liner continuity, thickness, and reconnection details. This is often part of the project closeout package.
• Return to service – Once inspections are complete and any punch-list items are resolved, the storm line is ready for normal operation, and can immediately perform during the next rainfall.

If you’re a property owner or manager and want to understand what this would look like on your site, you can explore real-world case studies of storm and sewer lining projects similar to yours.

Types Of Lining Technologies Used In Storm Water Pipes

Cured-In-Place Pipe (CIPP) Lining

CIPP is one of the most widely used trenchless methods for storm water pipe rehabilitation. A flexible liner tube, saturated with a thermosetting resin, is inserted into the host pipe and then cured to form a rigid, load-bearing pipe.

Key advantages for storm applications:

• Structural renewal – Properly designed CIPP can be fully structural, capable of carrying soil and live loads even if the host pipe continues to deteriorate.
• Smooth interior – Cured liners have a low roughness coefficient, often improving hydraulic performance even though slightly reduced diameter.
• Versatility – Works in many materials (clay, concrete, CMP, PVC) and a wide diameter range, from small laterals to very large storm drains.
• Custom thickness – Wall thickness can be engineered to match depth, loading, and host pipe condition.

NuFlow employs CIPP and UV-cured variations for situations where structural performance and long-term durability are critical, such as deep or traffic-bearing storm mains.

Spray-On And Spin-Cast Liners (Cementitious And Polymeric)

Spray-applied linings are ideal when you need a new corrosion-resistant or structurally enhanced inner surface without installing a full tube liner. Two main categories:

• Cementitious linings – High-strength cement or mortar is spin-cast or sprayed, then troweled or finished to create a new interior shell. Often used to rebuild deteriorated concrete or CMP and restore shape.
• Polymeric/epoxy coatings – Epoxy or polyurethane products are sprayed or spin-cast to create a thin but highly corrosion-resistant liner. In some formulations and thicknesses, these can also be semi-structural.

Benefits for storm pipes:

• Good for large diameters, man-entry pipes, and culverts where CIPP logistics are challenging.
• Excellent for corrosion protection in environments with salts, industrial runoff, or aggressive soils.
• Minimal loss of internal diameter, which helps maintain hydraulic capacity.

NuFlow’s epoxy coating systems are designed for long service life (50+ years in many applications) and can be tailored to the corrosion and abrasion conditions in your storm network.

Sliplining And Segmental Lining Systems

Sliplining involves pulling a smaller-diameter pipe (often HDPE or PVC) through the existing pipe, then grouting the annular space. Segmental systems use interlocking panels or segments, often in large culverts or tunnels, to form a new internal shell.

Pros:

• Simple, well-established methods with predictable engineering behavior.
• Suitable for very long runs or large culverts.
• Often economical where some loss of diameter is acceptable.

Cons:

• Noticeable reduction in internal diameter, which can affect hydraulic capacity.
• More challenging around numerous bends, inlets, and junctions.

Choosing The Right Lining Method For Different Pipe Materials And Diameters

Your choice of technology should be driven by:

• Pipe material – Corroded CMP may benefit from CIPP or cementitious rebuild plus coating. Concrete pipes often pair well with CIPP or spray linings. Plastics may only need corrosion protection or joint rehabilitation.
• Diameter and length – Smaller diameters (e.g., 4″–18″) typically favor CIPP or epoxy lining. Large-diameter storm drains and culverts may lean toward CIPP, spray/spin-cast systems, or segmental panels depending on access.
• Structural needs – If you require a fully structural solution, CIPP or structurally rated spray liners are usually preferred. For non-structural corrosion protection, thin epoxy or polyurethane coatings may suffice.
• Hydraulic constraints – Where you can’t afford to lose much capacity, low-roughness liners or thin-coat systems are attractive.
• Access and site constraints – Tight sites or limited access shafts may rule out some methods.

A trenchless specialist like NuFlow will evaluate your existing storm water assets and recommend the most appropriate technology mix based on risk, performance goals, and budget.

Engineering Considerations Specific To Storm Water Applications

Hydraulic Capacity, Flow Rates, And Roughness Coefficients

Storm systems are designed around peak flow events, so any rehabilitation must protect or improve hydraulic performance.

Key considerations:

• Diameter reduction vs. smoother surface – Lining often reduces the inside diameter slightly, but the smoother wall (lower Manning’s n) can offset this and sometimes even increase capacity.
• Design storms – Your engineer should check post-lining capacity against your target design storm (e.g., 10-year, 25-year, 100-year events) to confirm adequate performance.
• Backwater effects – Lined pipes may change hydraulic grade lines upstream of outfalls or junctions. Modeling helps avoid unintended ponding or surcharging.

In many cases, switching from rough, deteriorated concrete or CMP to a smooth CIPP or epoxy-lined surface results in equal or better hydraulic capacity even though a minor diameter reduction.

Handling Large Diameters, Multiple Inlets, And Catch Basins

Storm water systems are often more complex than sanitary lines:

• Multiple inlets and laterals connect at various angles and elevations.
• Catch basins and manholes interrupt straight runs.
• Large diameters (36″, 48″, 72″ and beyond) present constructability challenges.

Your lining design must address:

• How to access large pipes (man-entry vs. remote equipment).
• How many lateral/inlet reinstatements will be required and whether robotic tools can reach them.
• Whether partial lining (only the worst segments) or full-length rehabilitation makes more sense.
• How to handle transitions in diameter or material.

Experienced trenchless contractors adapt installation methods, using inversion, pull-in, or spray/spin cast approaches, to fit these complexities without excessive excavation.

Design Life, Structural Requirements, And Codes

For most owners, the goal is a multi-decade fix, not a band-aid.

Your design team should consider:

• Design life – Many modern lining systems are engineered and warrantied for 50+ years when installed correctly.
• Structural classification – Is the liner fully structural (Class IV), semi-structural, or non-structural? How will it perform if the host pipe continues to deteriorate?
• Loading conditions – Depth of cover, soil types, traffic loads (HS-20/HS-25 or heavier), and groundwater conditions.
• Applicable standards and regulations – Many jurisdictions reference ASTM standards for CIPP and other lining methods, alongside local stormwater codes and environmental rules.

NuFlow’s engineering teams work within these standards to ensure rehabilitated storm lines meet structural and regulatory expectations, not just short-term operational needs.

Dealing With Corrosion, Abrasion, And Chemical Exposure

Storm water flows can be harsh:

• Corrosion – Deicing salts, industrial runoff, and acidic soils attack metallic and concrete pipes.
• Abrasion – Sand, gravel, and debris carried during high flows scour the pipe interior.
• Chemical exposure – In some catchments, oils, fuels, or industrial contaminants may be present.

For long-term performance, your lining system should:

• Use corrosion-resistant materials (epoxy, polyester/vinyl ester resins, or polymer-modified mortars) appropriate to your environment.
• Have adequate thickness and hardness to resist abrasion.
• Be compatible with other components in your system (e.g., manhold repairs, joint seals, or outfall structures).

Matching material properties to your actual stormwater chemistry is crucial for achieving the expected 50-year design life.

Cost, Timelines, And Comparing Lining To Full Replacement

Typical Cost Drivers For Storm Water Pipe Lining Projects

Every project is unique, but common cost drivers include:

• Pipe size and length – Larger diameters and longer runs require more material and more complex installation equipment.
• Access conditions – Difficult access, deep manholes, limited staging space, or the need for temporary shafts all increase costs.
• Degree of deterioration – Heavily corroded or deformed pipes may require more extensive cleaning, spot repairs, or thicker liners.
• Number of inlets and laterals – Each reinstatement adds time and cost, especially in dense urban networks.
• Bypass and traffic control – Managing flows and maintaining public safety often represent a significant portion of project costs.
• Selected technology – CIPP, epoxy spray, cementitious lining, sliplining, and segmental systems all carry different unit costs.

NuFlow typically finds that trenchless solutions come in 30–50% below the total cost of open-cut replacement when you fully account for surface restoration, business interruption, and risk.

Budgeting And Bidding: What Owners And Managers Should Expect

When you’re budgeting or preparing to bid a storm water lining project, you should:

1. Start with a condition assessment – Don’t guess. Have the lines inspected and defects coded so bidders price the actual conditions.
2. Define performance goals – Structural vs. non-structural, design life, and hydraulic targets should be clearly stated.
3. Specify acceptable technologies – Many owners list CIPP, spray-applied liners, or other approved systems rather than prescribing a single method.
4. Plan for contingencies – Include allowances for unforeseen obstructions, extra cleaning, or spot repairs that might be discovered during work.
5. Compare life-cycle costs – Don’t just look at low bid. Consider design life, maintenance impacts, and future replacement risk.

Property owners and managers who work with NuFlow often appreciate the ability to phase projects, starting with the highest-risk segments, based on a clear condition and risk profile.

Side-By-Side Comparison: Lining Versus Open-Cut Replacement

Here’s how lining usually stacks up against traditional dig-and-replace for storm water pipes:

1. Cost

• Lining: Generally 30–50% less overall when site restoration is considered.
• Open-cut: Higher direct construction cost plus pavement, landscaping, utility relocations, and potential business losses.

2. Schedule

• Lining: Often completed in days per segment, with much shorter overall project durations.
• Open-cut: Weeks or months, especially in congested or high-traffic corridors.

3. Disruption

• Lining: Minimal surface impact: limited lane closures and smaller work zones.
• Open-cut: Major excavation, full lane closures, noise, dust, and extended inconvenience.

4. Risk

• Lining: Less risk of hitting unknown utilities or destabilizing nearby structures because excavation is limited.
• Open-cut: Higher risk of utility conflicts, public complaints, and environmental exposure.

5. Performance

• Lining: Long service life, improved corrosion resistance, and often improved hydraulics.
• Open-cut: New pipe also offers long life, but at greater upfront disruption and cost.

For many storm water assets, lining gives you 80–90% of the benefit of full replacement at significantly lower cost and with far less disruption, which is why it has become a go-to strategy for municipalities, campuses, and commercial properties.

Operational And Environmental Benefits Of Lining Storm Water Pipes

Minimizing Surface Disruption, Traffic Impacts, And Downtime

One of the biggest reasons you might choose lining is what doesn’t have to happen:

• No large, open trenches across busy streets or driveways
• No tearing up parking lots, landscaped campuses, or sports fields
• Less noise, dust, and general construction chaos

For commercial and institutional sites, that translates into:

• Lower business interruption and fewer complaints from tenants or customers.
• Easier traffic and pedestrian management.
• Shorter permit durations and fewer long-term road closures.

Storm water lining is often done from existing manholes, catch basins, or small access pits. NuFlow’s crews are trained to work efficiently in tight, sensitive environments so you keep operations going while critical drainage work is completed.

Reducing Infiltration, Exfiltration, And Sinkhole Risk

A lined storm pipe greatly reduces:

• Infiltration – Groundwater entering the pipe through joints and cracks, which can overload downstream systems or treatment plants in combined systems.
• Exfiltration – Storm flows leaking out into surrounding soils, leading to erosion, voids, and eventual surface collapse.

By re-establishing a continuous, watertight interior:

• You stabilize the surrounding soils.
• You restore reliable drainage paths, reducing roadway and yard flooding.
• You significantly lower the risk of future sinkholes or sudden pavement failures.

Environmental And Regulatory Advantages Of Trenchless Lining

Storm water regulations are getting stricter, and failures are more visible than ever. Lining supports compliance and sustainability goals by:

• Protecting receiving waters – Preventing uncontrolled discharges into soils and groundwater reduces pollution pathways.
• Supporting MS4 and stormwater management plans – Rehabilitated infrastructure helps you meet system performance and maintenance commitments.
• Reducing carbon footprint – Less excavation means fewer truck trips, less aggregate and asphalt use, and lower embodied carbon overall.
• Limiting disturbance in sensitive areas – In wetlands, riparian corridors, or protected habitats, trenchless work can avoid clearing and grubbing.

For municipalities and utilities looking to stretch limited capital while meeting regulatory obligations, trenchless storm water pipe lining has become an essential tool. If you oversee public systems, NuFlow’s municipalities & utilities resources can help you evaluate network-wide rehabilitation strategies.

Planning And Executing A Successful Storm Water Lining Project

Condition Assessment And Prioritizing Segments For Repair

A successful project starts with knowing what you actually have underground.

Steps you should take:

1. Inventory your assets – Map storm lines, materials, ages, diameters, and known trouble spots.
2. Perform CCTV inspections – Use standardized defect coding (e.g., NASSCO PACP where applicable) to rate condition.
3. Assess risk – Consider consequence of failure (near buildings, roadways, or critical infrastructure) alongside pipe condition.
4. Prioritize – Tackle the worst/highest-risk segments first while planning long-term for the rest.

This approach helps you phase work effectively, smoothing budget impacts while addressing the riskiest problems before they become emergencies.

Coordinating With Stakeholders And Utility Locates

Even though trenchless work is less intrusive, coordination still matters:

• Utility locates – Always confirm the location of other underground utilities, particularly near access pits or potential bypass runs.
• Traffic and access planning – Coordinate with facility managers, tenants, or public works to schedule work during off-peak hours or lower-impact periods.
• Communication – For public projects, inform residents or businesses about the duration, purpose, and expected benefits of the work.

For larger networks or multi-site owners, NuFlow coordinates across stakeholders to sequence work efficiently, minimizing disruption while maintaining strong safety and quality standards.

Quality Control, Testing, And Long-Term Maintenance

Your lining project shouldn’t end when the last liner is cured. To protect your investment, you should:

• Require final CCTV video – Documented evidence of liner condition, connections, and workmanship.
• Specify material testing – Resin cure tests, thickness checks, and structural calculations where appropriate.
• Keep detailed records – As-builts, submittals, and warranties should be stored with your asset management records.
• Plan periodic inspections – Even lined systems benefit from periodic CCTV checks, especially after major storm events.
• Maintain catch basins and inlets – Keeping surface structures clean helps your rehabilitated pipes operate at full capacity.

NuFlow’s trenchless systems are backed by warranties and a proven track record of rehabilitating storm, sewer, and water lines worldwide. You can see how similar projects have performed over time in our storm and sewer case studies.

If you’re a contractor who wants to add high-quality trenchless lining to your services, consider becoming part of the global NuFlow contractor network or exploring how to become a contractor with full training and technical support.

Conclusion

Storm water infrastructure is easy to ignore, until it fails. When you start seeing flooding in odd places, unexplained pavement settlement, or recurring erosion, it’s a sign your buried storm lines may be reaching the end of their original service life.

Sewer lining for storm water pipes gives you a powerful alternative to digging everything up. With CIPP liners, epoxy coatings, spray-applied systems, and other trenchless methods, you can:

• Restore structural integrity and hydraulic performance
• Reduce infiltration, exfiltration, and sinkhole risk
• Extend asset life by 50+ years
• Avoid the disruption, risk, and cost of full replacement

The key is choosing the right technology, designing for your specific hydraulic and structural needs, and working with an experienced trenchless provider.

NuFlow has decades of experience rehabilitating storm, sewer, and water systems for residential, commercial, and municipal clients using minimal-disruption trenchless technologies. If you’re facing storm water failures or want to proactively assess your system, you can get help with plumbing and drainage problems or request a free consultation through our plumbing problems page.

With the right plan and partner, you can fix failing storm water pipes from the inside out, protecting your property, your community, and your budget for decades to come.

Frequently Asked Questions About Sewer Lining for Storm Water Pipes

What is sewer lining for storm water pipes and how does it work?

Sewer lining for storm water pipes is a trenchless rehabilitation method that creates a new “pipe within a pipe.” Crews access the storm line through manholes or catch basins, clean it, install a liner (such as CIPP or spray-applied coatings), cure it in place, and restore inlets, providing a smooth, long-lasting interior.

When is sewer lining for storm water pipes better than full pipe replacement?

Lining is usually the better option when the storm pipe is cracked, corroded, or jointed but still mostly continuous, and when you need to minimize surface disruption under roads, parking lots, or buildings. It’s also preferred when budgets are tight, access is limited, or faster turnaround is critical.

How long does storm water pipe lining last, and is it structurally reliable?

Modern storm water pipe lining systems, including CIPP and epoxy coatings, are typically designed for 50+ years of service life. When properly engineered, many liners can be fully structural, capable of carrying soil and traffic loads even if the host pipe continues to deteriorate, while also improving corrosion resistance and hydraulic performance.

How much does it cost to line storm water pipes compared with excavation?

Costs depend on diameter, length, access, degree of deterioration, number of inlets, and chosen technology. However, trenchless lining for storm water pipes commonly comes in about 30–50% cheaper than open-cut replacement once pavement, landscaping, traffic control, business disruption, and restoration expenses are included in the total project cost.

Can sewer lining be used on all types and sizes of storm water pipes?

Most common storm pipe materials—corrugated metal, reinforced concrete, clay, and many plastics—can be rehabilitated with some form of lining. CIPP and epoxy are often used from 4″ up through large-diameter mains, while spray/spin-cast and segmental systems are well-suited for very large culverts or man-entry pipes, depending on access and hydraulic needs.