Ask the Expert: Your Top Manhole Rehabilitation Questions Answered — June 2026

Each month, our technical team answers the most common questions submitted by community members. This month’s Q&A focuses on polyurea application, inspection protocols, and funding.

Q: What temperature range is acceptable for polyurea application in manholes?

— Public Works Director, Milwaukee, WI

A (Marcus Webb, Technical Director): Polyurea systems are generally specified with a substrate temperature range of 50–90°F (10–32°C), but the real constraint is the delta between substrate temperature and dew point. The substrate temperature must be at least 5°F above the dew point in the manhole atmosphere to prevent moisture condensation that will interfere with adhesion.

In practice, for cold-weather operations, we recommend pre-warming the substrate surface with a propane torch or heat blower and monitoring both surface temperature and dew point continuously. Most certified applicators have protocols for this — ask your contractor to document their cold-weather application procedure as part of the QC plan.

Don’t try to apply polyurea when substrate temperatures are below 40°F, even with heating. The risk of adhesion failure is too high and the cure behavior changes enough to make reliable quality control very difficult.

Q: Can we use MACP inspection data collected by our own crew, or does it have to come from NASSCO-certified inspectors?

— City Engineer, Des Moines, IA

A (Heidi Lee, Executive Director): NASSCO’s MACP certification is for the inspection protocol and for inspectors who want to demonstrate competency in using it — it’s not a legal requirement for conducting inspections or using the resulting data.

That said, certification matters for a few practical reasons. First, certified inspectors have demonstrated understanding of the defect codes and grading criteria, which means your data is more likely to be accurate and consistent. Second, if you’re pursuing SRF financing or operating under a regulatory compliance program, your state agency may ask about inspector qualifications — NASSCO certification provides clear documentation of competency.

If you’re planning to have your crew conduct MACP inspections, have them complete the NASSCO training and certification process. It’s relatively low cost and one-time — the data quality improvement alone is worth it, let alone the regulatory and funding benefits.

Q: We have 15 manholes in an area with constant traffic. What’s the right approach for traffic management?

— Contractor Project Manager, Houston, TX

A (James Torretta, Field Operations Lead): Traffic management for manhole rehabilitation is genuinely one of the higher-risk and higher-cost elements of any program in urban environments. The key decisions are:

First: can you work at night? Night work in Houston-level traffic cities is almost always worth the shift differential. Your production rates may drop slightly but your traffic control costs decrease dramatically and your crew exposure to moving traffic is reduced.

Second: work with your traffic engineer on a rolling lane closure plan that allows you to move through the 15 manholes without resetting full traffic control for each one. If they’re on the same street, you may be able to set up a single extended closure and move down the street.

Third: pre-positioned equipment is your friend. Reduce the number of times trucks have to move by staging material ahead and working a few manholes ahead with surface prep before the spray crew follows behind.

Document your traffic control plan in writing, get it approved by your traffic authority before mobilizing, and make sure every crew member knows the emergency response procedure for a traffic intrusion. Traffic control is safety-critical, not just logistics.

Q: How do I document manhole rehabilitation for our CMOM program?

— Environmental Compliance Manager, Columbus, OH

A (Dr. Sandra Okafor, Research Lead): CMOM documentation for manhole rehabilitation should capture the complete lifecycle of the work: pre-rehabilitation condition (MACP inspection data and photos), rehabilitation method and materials used (including material data sheets and certifications), application records (surface prep verification, QC test results), and post-rehabilitation condition verification (adhesion test results, visual inspection, any flow monitoring response).

Your CMOM program documentation should also connect the individual manhole rehabilitation records to your system-wide asset management and I/I reduction program — showing regulators that the work is part of a systematic program rather than one-off reactive maintenance.

If you’re preparing for a regulatory review, our Resources page has a documentation checklist that covers the key elements most state environmental agencies look for in CMOM program documentation for collection system rehabilitation.

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