
Trenchless Technology 2025 Rehabilitation Project of the Year Honorable Mention
Arkona Road 72- to 76-in. Transition UV CIPP Culvert Rehabilitation
This Spring 2025 UV CIPP installation in Washtenaw County, Michigan, rehabilitated an aging, circular CMP culvert. It transitioned from 72 in. to 76 in. diameter mid-pipe and also included a 17-degree bend. The culvert conveys a creek underneath Arkona Road in a stretch of Washtenaw County frequently trafficked with heavy farm equipment.
Also of concern was the transition from 72 to 76 in.; the culvert was constructed from different CMP sizes. The 72- and 76-in. diameter sections had been fitted together about 60 ft into the 100-ft host pipe. The inverts were set flush at the transition joint, but the inevitable void at the crown area from the mismatch had not been adequately sealed. It was at this point a source of infiltration and debris.
Project Background
For the project, Pipeline Management Co. (PMC) enlisted a sister company with considerable UV-lining experience, Precision Trenchless. The liner was designed at 13.7-mm thickness with ASCE MOP 145, manufactured by IMPREG LLC, which also provided on-site support.
To handle the transition, precise circumferential measurements were taken well in advance of the installation. Accurate longitudinal and circumferential measurements around the area of the transition were important. This was how the manufacturer designed the glass layer configuration according to the transition profile. They set the transition liner “cone” at the point along the pipe where the transition occurred.
The most challenging step was the staging of the crate, which feasibly could only be lowered into place from road level. This was accomplished with two rotator trucks rigged with a system of guy lines. The system allowed the crate – weighing in at close to 16,000 lbs – to be guided down to the landing area at the inlet.
Once in place, the crew proceeded cautiously with the inflation stage. An airlock was used in the process of inserting the UV light-train through the face-plate of one of the packers, with pressures still held at levels appropriate for manned-entry. After this point, the inflation proceeded in a number of ‘calibration steps’.
These steps ensured the liner gradually stretched and adapted to the profile of the host pipe. Especially at the transition section, where a close fit per design would only be accomplished by taking full advantage of the liner’s expansion capabilities. Gradually coaxing the un-fixed overlapping layers to ‘unfurl’ into the irregular transition space, while still maintaining full overlap of all the thickness layers.
Why Project Is Outstanding
All in all, the cure took around five hours. The total operation took about 24 hours – from 6 a.m. until 6 a.m. on the following day, at which point the road and culvert were returned to service.
This project is outstanding not only on account of the 76-in. section being the single largest host pipe by diameter rehabilitated with UV CIPP in North America as of time of writing. It is also outstanding for the additional challenge of the mid-pipe diameter transition combined with a 17-degree bend. Worldwide, there have been a handful of 2000-mm (~78 in.) diameter UV CIPP installations. However, as of 2025, the largest host pipe rehabilitated in North America was 72 in.
The transition, as well as the bend, increased the assumed risk for a number of reasons. Any irregularity throughout the length of a shot (also including bends) increases the likelihood that something might compromise the air calibration hose (aka ‘inner film’). This hose must be wholly intact in order to maintain working pressure. It prevents air intrusion, which can quickly cause delamination in the resin-glass layers. Such inner film-damage hazards included potential chafing of the cure rope against the pipe walls during the bend. Additionally, the light train could get caught when navigating the contours of the transition. A flawless light train transit in these circumstances requires experience and finesse.
Project Details
Project Owner: Washtenaw County Road Commission
Engineer: Washtenaw County Road Commission
Contractors: Pipeline Management Company, Precision Trenchless (divisions of PowerVac of Group) and Brewer’s Towing (subcontractor)
Manufacturers/Suppliers: IMPREG and IBG
Value of Trenchless Project (US$): $400,000
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