Design Approach, Inspection For Manhole Rehabilitation Technologies

3nd In A 3-Part Series
By Gerhard “Gerry” P. Muenchmeyer, P.E., NASSCO Technical Director | November 2011, Vol. 66 No. 11

Second, once the material is applied and cured, the trained inspector must enter the manhole to perform a detailed visual inspection of the finished surface and note any potential defects. Holidays and pinholes can best be detected upon entry into the manhole structure.

Third, the quality of the applied product must be assured through required testing, that is applicable to the material applied and as specified in the contract documents.

Should all manhole rehabilitation products require inspection and testing to verify proper installation?

Carpenetti: “Yes, inspection and testing is paramount to the successful completion of a manhole rehabilitation project. A lot of products get a bad rap due to improper installation. The best products in the world will fail if they are installed incorrectly.”

Johnson: “Absolutely. Testing such as holiday testing (on corrosion protection installations, typically 125-250 mils) and adhesion testing promote good installation practices. Also, verification is needed from a third-party, independent testing of physical properties performed by certified materials testing company, specifically those that use the same physical properties in their thickness designs. An example would be both short-term and long-term flexural modulus that is used in ASTM F1216-10.”

Kampbell: “Construction observation is a bargain for the owner when the inspectors are properly trained in how to identify critical steps in the lining’s installation that assure long-term performance. Yes, there should be construction observation of the installation process and quality assurance testing used to document the success of these installations.”

It seems that there is, at least, a consensus among the participants that good qualified and certified inspection is a must for all manhole rehabilitation activities. NASSCO is in the final stages of developing an Inspector Training and Certification Program (ITCP) for manholes that is designed to educate inspectors and engineers on different technologies and how to properly inspect and test the products during and after installation.