Inspection, Testing, and Rehabilitation of Collection Systems
Inspection and testing reveal condition before failure. Class IV candidates should know the main methods, what each detects, and how results drive rehabilitation decisions.
CCTV inspection is the primary tool for pipe interior condition; operators code defects such as cracks, roots, offset joints, and infiltration. Manhole inspection documents structural condition and inflow sources. Smoke and dye testing trace connections and inflow. Flow monitoring quantifies I/I. Rehabilitation methods include cured-in-place pipe (CIPP) lining, spot repairs, grouting, and manhole rehabilitation. Trenchless methods reduce excavation and disruption.
Traps
A common trap is confusing CCTV (interior pipe) with manhole inspection (structure). Another is assuming lining fixes every defect: CIPP addresses interior structural and infiltration problems but may not correct a badly offset joint or a collapsed section, which requires excavation. Also watch questions on defect coding: a root intrusion is a maintenance issue; a deformed or collapsed pipe is a structural failure.
Rule of thumb
Inspect before you rehabilitate, and rehabilitate by priority. Rank defects by severity and consequence of failure, and pair inspection data with the asset management record.
Worked example
CCTV shows a 20-ft section with a severe offset joint and root intrusion. Spot repair may handle the root, but the offset joint may need excavation or a structural liner. Document the defect code and condition rating so the decision is defensible.