3.3 Closed-Circuit Television (CCTV) Inspection & NASSCO PACP

Closed-Circuit Television (CCTV) Inspection & NASSCO PACP

Quick Answer: CCTV pipeline inspection uses robotic crawlers with 360° pan-and-tilt cameras to visually inspect and log sewer conditions. The NASSCO PACP (Pipeline Assessment Certification Program) standardizes defect documentation into Structural and Operational/Maintenance (O&M) categories across a Grade 1 to 5 severity scale, ensuring consistent data for asset management and rehabilitation planning.

Closed-Circuit Television (CCTV) inspection is the cornerstone of proactive collection system condition assessment, asset management, and infiltration/inflow (I/I) detection. Certified collection operators must be thoroughly familiar with CCTV equipment operation, standard inspection protocols, and NASSCO PACP defect coding conventions.

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1. CCTV Equipment Architecture

A modern CCTV inspection unit is typically housed in a dedicated step-van or trailer containing a climate-controlled operator studio and a rear equipment bay:

                    CCTV ROBOTIC CRAWLER SYSTEM

   +-----------------------------------------------------------+
   |  [Video Monitor & PACP Data Console] (Studio)             |
   +-----------------------------+-----------------------------+
                                 | Calibrated Cable (Tether)
                                 v
                +--------------------------------+
                | Digital Distance Cable Reel    |
                +----------------+---------------+
                                 |
                                 v
                       (Downstream Manhole)
                                 |
               ==================+==================
               |                                   |
               |     [Pan-and-Tilt Camera Head]    |
               |             //====\\              |
               |      [LEDs](  (O)  )[LEDs]        |
               |             \\====//              |
               |       +------------------+        |
  Pipe Crown   |       | Robotic Crawler  |        |   Pipe Crown
  -------------+-------+------------------+--------+-------------
  Pipe Invert  |         (O)          (O)          |   Pipe Invert
  ===============================================================
               <=== Crawler Advances Upstream (Max 30 ft/min) ===

Primary Components

1. Robotic Transporter (Crawler): Steerable, multi-wheel or tracked all-wheel drive crawler capable of navigating pipes from 6" to 48"+ diameter. Wheel sizes and weights are adjusted to match pipe material and water depth.
2. Pan-and-Tilt Camera Head: Features 360° continuous pan rotation and 270° optical tilt with high-intensity LED lighting arrays. It allows perpendicular (90°) viewing of pipe joints, lateral service taps, and localized defects.
3. Cable Reel & Calibrated Encoder: Armored multi-conductor cable transmitting video signals, crawler control commands, and power. A digital distance encoder continuously logs travel footage (chainage) with an accuracy of $\pm 1%$.
4. Data Acquisition Software: Specialized PACP-compliant logging software that overlays continuous chainage footage, pipe diameter, material, date, manhole IDs, and defect codes directly onto the recorded digital video (MP4).

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2. Standard Operating Procedures (SOP) for CCTV

To ensure legally defensible and technically accurate data, operators follow standardized inspection protocols:

• Pre-Cleaning Requirement: Pipes should generally be cleaned with a hydro-jetter prior to CCTV inspection so that settled silt and grease rings do not obscure structural cracks or invert defects. (Exception: dedicated pre-cleaning surveys to assess grease/grit loading).
• Speed Limit: NASSCO PACP standards mandate that camera travel speed must never exceed 30 feet per minute (0.5 ft/sec) during continuous travel.
• Lateral & Joint Inspections: The camera must stop at every service lateral connection, pan 90° into the lateral tap, and record clock position (e.g., 10:00 or 02:00), connection type (factory tee, saddle, break-in tap), and structural condition.
• Footage Calibration: The footage counter must be zeroed precisely at the center point or interior face of the starting manhole and verified at the terminal manhole face.

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3. NASSCO PACP Defect Classification

The National Association of Sewer Service Companies (NASSCO) developed the Pipeline Assessment Certification Program (PACP) to eliminate subjective terminology (e.g., "bad crack" or "dirty pipe") by providing standardized four-letter alpha codes, severity modifiers, and clock-position references.

PACP divides all pipeline observations into two primary classifications:

+-------------------------------------------------------------------------+
|                   NASSCO PACP DEFECT CLASSIFICATIONS                    |
+------------------------------------+------------------------------------+
| 1. STRUCTURAL DEFECTS              | 2. OPERATIONAL & MAINTENANCE (O&M) |
| (Affects physical pipe integrity)  | (Affects flow capacity / hydraulic)|
+------------------------------------+------------------------------------+
| • Cracks (Longitudinal, Circ., M)  | • Root Intrusion (Fine, Med, Mass) |
| • Fractures (Circumferential, M)   | • Grease Accumulation (Attached)   |
| • Broken Pipe / Missing Wall/ Hole | • Settled Deposits (Grit, Rocks)   |
| • Deformed / Deflected Pipe (>5%)  | • Encrustations (Mineral, Scale)   |
| • Joint Separation / Offset Joint  | • Infiltration (Drip, Run, Gusher) |
| • Collapsed Pipe                   | • Obstructions (Intrusive Laterals)|
+------------------------------------+------------------------------------+

                  CLOCK-POSITION DEFECT NOTATION
                             12:00 (Crown)
                                  |
                 10:00            |            02:00
              (Service Tap)       |         (Service Tap)
                       \          |          /
                        \         |         /
          09:00 (Springline) -----+----- 03:00 (Springline)
                                 / \
                                /   \
                               /     \
                                  |
                             06:00 (Invert)

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4. PACP Severity Grading Scale (1 to 5)

PACP assigns a numerical severity score from 1 to 5 to every identified defect based on the risk of structural failure or hydraulic blockage:

Pipe Rating Index (PRI)

PACP software aggregates individual defect scores across a pipe segment to generate standardized asset management scores:

$\text{Pipe Structural Score} = \sum (\text{Structural Defect Grades})$ $\text{Structural Pipe Rating Index (SPRI)} = \frac{\text{Total Structural Score}}{\text{Total Number of Structural Defects}}$

A pipe with multiple Grade 4 and Grade 5 defects receives the highest renewal priority for trenchless lining (CIPP) or emergency point repair.

Other Locating and Inspection Platforms

The Need-to-Know Criteria pair CCTV with acoustic evaluation, visual, and drone inspection, because no single platform suits every asset.

• Drones (UAVs). Aerial drones photograph outfalls, stream crossings, easements grown over with vegetation, and treatment or lift station sites for asset records. Confined-space and in-pipe drones — small collision-tolerant aircraft with onboard lighting and cameras — inspect large-diameter interceptors, siphon chambers, wet wells, and tunnels without a human entry. That is their decisive advantage: an asset that would otherwise require a permit-required confined space entry can be inspected from outside it. Their limits are flight time measured in minutes, dependence on artificial lighting, and the inability to measure or clean.
• Zoom/pole cameras. A pole-mounted zoom camera lowered into a manhole surveys both incoming and outgoing pipe from the surface in a few minutes. It is the standard rapid-screening tool for prioritizing which segments deserve a full CCTV run — far faster than a crawler, but it cannot see past the first bend or grade a defect to full PACP standards.
• Laser profiling and sonar. Laser rings measure ovality and capacity loss above the waterline; sonar profiles the silted portion below it. Combined with CCTV in a multi-sensor run, they quantify deformation and sediment that video alone can only estimate.
• Push cameras. Small self-contained reels for laterals and small-diameter lines that a crawler cannot enter.