The North American standard for CCTV-based sewer pipe defect coding and condition grading.

The NASSCO PACP coding system is the backbone of standardized sewer inspection. Every observation logged during a CCTV run is classified through a three-level hierarchy: the inspector selects a code family, then a specific code within that family, and then a descriptor that refines the observation. This hierarchy ensures that two inspectors looking at the same defect will produce the same coded output, regardless of their employer, geography, or equipment. The form's Observation Log captures this through the Code Family / Group field and the Descriptor / Modifier field. Each observation is tied to a distance measurement (footage from the start of the segment), a clock position that locates the defect on the pipe's cross-section (using the 1-to-12 clock face convention), and an optional clock-to position when the defect spans a circumferential range.

The complete PACP coding manual is published by NASSCO.

NASSCO PACP uses a 5-point condition grading scale that applies to individual defect observations, not to the pipe segment as a whole. Grade 5 represents the most significant finding — a condition where the pipe has already failed or failure is imminent — while Grade 1 represents minor, early-stage deterioration consistent with normal aging. The grade assigned to each observation is determined by a combination of the defect code and its measured value. For example, a Deformed pipe at 10% loss of cross-section receives a lower grade than one deformed at 30%, and a Root Ball (Grade 5) is more severe than Fine Roots (Grade 2). The segment's overall condition is expressed through composite metrics: the Structural Rating sums all structural defect grades, the O&M Rating sums all maintenance-related grades, and the Quick Rating compresses the entire defect profile into a 4-character code. The Quick Rating follows the format of peak grade followed by counts — "4213" means the worst defect is Grade 4, occurring twice, with one Grade 3 defect and three Grade 1 defects. This compression allows asset managers to sort, filter, and prioritize thousands of pipe segments without opening individual inspection reports.

One of PACP's most distinctive features is its handling of continuous (linear) defects. In a sewer pipe, many conditions are not isolated to a single point — roots may span 40 feet, a longitudinal crack may run the length of an entire segment, or deposits may accumulate over a 20-foot stretch. PACP addresses this with the Continuous Defect flag on each observation entry. The inspector has three options: Single Point (the default, for defects that occur at one footage), Start Continuous (S), and Finish Continuous (F). When the CCTV camera encounters a defect that begins at, say, 10 feet and extends to 50 feet, the inspector logs two entries: the first at 10 feet with the Start flag and the defect code, and the second at 50 feet with the Finish flag and the same code. The inspection software then treats the span from 10 to 50 feet as a single continuous defect for grading and reporting purposes.

This Start/Finish mechanism is critical for accurate condition assessment because it prevents both over-counting (logging the same crack at every foot) and under-counting (logging only the start point and missing the extent). The span length directly affects rehabilitation cost estimation — a 5-foot root intrusion requires a different intervention than a 50-foot one, even if both are coded identically. In the digital form, the Continuous Defect field in the Observation Log provides three options: "Single Point (Standard)," "Start Continuous (S)," and "Finish Continuous (F)." Smart form implementations track open Start entries and prompt the inspector when a matching Finish has not been recorded before the end of the segment — a common data quality issue in manual workflows.

For manhole structures at each end of the pipe segment, the companion NASSCO MACP standard. Explore all available inspection standards in the standards library.