CapPlan is a comprehensive, state-of-the-art decision support tool that helps wastewater utilities effectively determine sewer rehabilitation needs and prioritize projects for short and long term benefits. This includes the ability to develop a sound, cost-effective capital program with improved system performance. CapPlan considers both system structural (and O&M) condition assessment and risk assessment of the probability and consequence of failure for each asset.

System structural condition is determined through collection system evaluation studies using CCTV (closed circuit television) data. This allows defect coding to be assigned for each asset (e.g., based on NASSCO/PACP, WRc, or other defect standards) for describing internal sewer pipe conditions with a pre-determined grading system. Example CCTV condition ranking and defect coding are shown in the tables below.

NASSCO PACP Structural Condition Grading System

Example Customized (Utility Specific) CCTV Condition Ranking

Example PACP Defect Coding

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The coded and rated CCTV data are sorted and used to generate a list of sewer segments requiring rehabilitation. The sort is based on the utility’s criteria to fit the goals and financial capability of the rehabilitation program. A user-defined decision-tree then determines for each segment (defect) the most cost-effective methodology to complete the rehabilitation. This is basically a series of tests to determine whether to leave alone, rehabilitate or replace a given pipe with one or more major defects or multiple minor defects.

The decision process will normally consider all factors required to select the best rehabilitation methodologies including hydraulic capacity needs, methodology limitations, physical pipe characteristics (e.g., age, diameter, material), surface restoration, unit costs, length of point repairs to total length of segment, etc. The decision tree is fully customizable by the user to meet the utility specific criteria. An example rehabilitation analysis decision tree is shown below.

Example Sewer Pipe Rehabilitation Decision Tree

Assets can also be ranked according to the probability and consequences of failure to the community. Probability of failure can depend on predictive deterioration, failure history and CCTV data. The data is described as number of collapses per mile (km) per year for various pipe material and diameter as well as number of blockages per mile (km) per year as a function of pipe material and age. Example blockages and collapses curves are shown below.

Consequence of failure can depend on pipe attributes such as depth, number of connected customers, and proximity to critical facilities (e.g., rivers, water bodies, wetlands, tourist sites, schools, hospitals, fire stations). Consequence of failure scores can be expressed in any user-desired scale such as “high” impact, “medium” impact and “low” impact for the various pipeline assets. Assets most critical to system operation will normally rate higher on the consequence scale; assets in poorer condition will have a higher probability of failure. The risk of each asset is then calculated as the product (multiplication) of its probability and consequence of failure. Assets with the greatest risk should receive the most attention. This risk assessment methodology provides the basis for a prioritized list of maintenance and capital improvements that help achieve the optimum level of service.

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Benefits of CapPlan:

Traditional Process	CapPlan Automated Process

CapPlan comprehensive capabilities will greatly assist wastewater utilities in making informed decisions and develop a focused maintenance management and capital program to ensure the most reliable and cost efficient sewer collection system and keep the system operating properly into the future.