Project Overview

• Client: Major Research University
• Location: St. Louis, Missouri
• Pipe Scope: 300 ft of 24-inch mainline + 300 ft of 12-inch pipe (600 ft total)
• Depth Below Surface: 25 feet
• Problem: New pipes with failing joint seals — infiltration and exfiltration risk adjacent to academic buildings
• Method: Structural UV-cured GRP Cured-in-Place Pipe (CIPP) Lining
• Contractor: Pelican Underground — Certified Saertex Installer
• Equipment: ProKASRO Professional UV Curing Unit
• Standards: ASTM F1216 / ASTM F2019 — NASSCO PACP inspection grading
• Time to Complete: 1 Weekend (single mobilization)
• Design Life: 50-Year Minimum (manufacturer-certified)

A Campus-Critical Repair With No Feasible Path to Open-Cut

Major research universities run on uninterrupted infrastructure. When 600 linear feet of sewer pipe at a St. Louis campus began showing premature joint-seal failures — creating both infiltration and exfiltration risk across the collection system — the facilities team faced a scenario where the standard playbook didn't apply. The pipes themselves were relatively new, but the seals had failed prematurely. And the pipes ran 25 feet beneath active academic buildings.

Traditional open-cut replacement would have required excavation to 25-foot depth immediately adjacent to load-bearing structures. The university's facilities team correctly ruled it out. Pelican Underground — a certified Saertex UV GRP installer in the TrenchlessNet contractor network — was engaged to deliver a structural rehabilitation using UV-cured CIPP lining, completing the full 600-foot restoration over a single weekend mobilization with zero excavation.

The Challenge: Three Obstacles That Ruled Out Conventional Repair

This was not a standard sewer repair. The combination of depth, proximity to structures, and space constraints created a scenario where traditional excavation was not viable — and the stakes were non-negotiable.

Obstacle 1 — Depth: 25 Feet Down

The failing sewer lines ran 25 feet below the surface. Excavating to that depth is a full civil engineering undertaking in its own right — requiring engineered shoring, confined-space entry protocols under OSHA 1926 Subpart P, significant heavy equipment, and mandatory dewatering coordination. At this depth, the cost and schedule gap between open-cut and trenchless rehabilitation typically exceeds the cost of the repair itself.

Obstacle 2 — Proximity to Campus Buildings

The pipe routes ran close to load-bearing campus structures. Digging at 25-foot depth in those locations carried a real risk of undermining building foundations — a risk the university's facilities team would not accept under any construction schedule. Geotechnical review flagged differential settlement potential in the soil layers adjacent to the foundation envelopes.

Obstacle 3 — Insufficient Working Surface Area

The excavation footprint required to safely access 25-foot-deep lines — including proper 1:1 or 1.5:1 slope benching under OSHA standards — would have exceeded the allowable working area on campus. There was simply not enough surface space to dig, even if the other obstacles had been solvable.

Pelican Underground's Approach: UV-Cured GRP CIPP

The chosen method was structural Cured-in-Place Pipe (CIPP) lining using Saertex UV-cured glass-reinforced polymer (GRP) liners — the liner system specified on demanding municipal and institutional rehabilitation projects worldwide. UV-cured GRP produces a higher flexural modulus per unit wall thickness than felt-based systems and cures substantially faster than hot-water or steam curing — the decisive fit for large-diameter rehabilitation on a compressed weekend schedule.

Why UV-Cured GRP Was the Right Choice

• Higher structural rating per unit wall thickness — a thinner liner achieves equivalent structural performance compared to felt-based CIPP, preserving more host-pipe hydraulic capacity.
• Faster cure times — a 300-ft run of 24-inch liner typically completes the cure cycle in 3–5 hours with UV, compared to significantly longer thermal cure windows.
• Lower styrene emissions during cure — a practical consideration on active campus environments with adjacent occupied buildings.
• Proven large-diameter performance — UV-cured GRP is the standard liner system on municipal mainline rehabilitation in North America and Europe.
• Manufacturer-certified 50-year design life — documented by Saertex per ASTM F2019 standards, giving the university a defensible long-term capital-life assumption.

The Equipment & Materials Chain

Pelican Underground operates as a certified Saertex installer, with Saertex UV GRP liners sourced directly and staged on-site at project mobilization. UV curing was performed using a ProKASRO Professional Curing Unit — the equipment calibrated on-site to deliver consistent UV dose across both pipe diameters in the single mobilization window. Pre- and post-lining documentation was captured using NASSCO PACP-graded CCTV inspection, providing the university with defensible before-and-after condition records across the full 600-foot scope.

The Execution: 600 Feet, One Weekend, No Trenches

The project was mobilized in a single weekend window, executing the following sequence:

1. Pre-Lining Camera Inspection & Pipe Assessment. All 600 feet of pipe was inspected with a NASSCO PACP-graded CCTV system. Every failing seal was located and coded, internal geometry was verified at both diameters, and the baseline condition was established for warranty purposes.
2. Liner Preparation & Equipment Staging. Saertex UV-cured GRP liners were measured, cut to length, and staged at the access point. The ProKASRO curing unit was calibrated on-site for consistent UV dose across both 24-inch and 12-inch diameters.
3. Installation — 300 ft of 24-inch Mainline. The GRP liner was inserted into the 24-inch main through an existing access opening — no new excavation required. The ProKASRO UV light train was pulled through the liner, curing the GRP in place from the inside out to form a structurally independent, jointless new pipe within the host.
4. Installation — 300 ft of 12-inch Pipe. The identical UV-cure process was applied to the 12-inch line. GRP material conforms precisely to the internal geometry of the host pipe, sealing all joints and defects without ground disturbance.
5. Post-Cure Inspection & Verification. Final PACP-graded CCTV inspection documented liner adhesion, joint sealing, and structural integrity across the full 600 feet. The university received manufacturer certification confirming compliance with the 50-year design-life specification.

Dig vs. No-Dig: Why Trenchless Was the Only Viable Path

At this depth and building-adjacency profile, the open-cut-vs.-trenchless comparison was not a cost-per-foot discussion — it was a feasibility discussion. Here is how the two approaches measured against the specific university scenario:

Project Results: 600 Feet Restored. One Weekend. Zero Trenches.

The project was delivered on schedule, within the allotted weekend window, with no disruption to campus operations, landscaping, or surrounding structures.

Why Institutional Owners Choose Pelican Underground

University campuses, hospital complexes, historic districts, and dense commercial cores share the same structural reality: the conditions that damage sewer infrastructure over time are the same conditions that make open-cut repair unacceptable. This project is a reference case for how UV-cured GRP CIPP handles that constraint set. The capability profile required is not generic. Pelican Underground brought the following to the job — each item publicly verifiable:

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