Maintenance activities include flushing and cleaning activities, CCTV analyses, air testing, and control and erosion repairs. Provide summary information that shows the maintenance activities undertaken for the entire collection system. This could include the miles of pipe cleaned; pump station operation and maintenance program description, etc. All of this should be provided in order for a full assessment to be conducted. All events that lead to any problems in the system should be mentioned in the assessment. A thorough system description of the current conditions is very important. The following describes the factors that are important in making rehabilitation assessments.
Identify the length and/or inch-miles of gravity sewers/interceptors only in the entire area where the work will occur. If force mains are included, distinguish between gravity sewers and force mains. Provide a map for sewer lines; utilize the following definitions for Good, Fair, and Poor:
* Good – The gravity sewer lines have adequate capacity to pass peak flows and have good structural integrity with minimal obstructions such as root intrusions. Force mains have adequate capacity to pass peak flows and good structural integrity with no cracking or other signs of age.
* Fair – The gravity sewer lines allow flow but have some structural integrity issues such as cracks and some intrusions such as roots. Force mains show some signs of wear.
* Poor – Flow within gravity sewer lines is limited due to structural issues (e.g. offset joints) or imminent structural failure. Intrusions such as roots are high. Force mains show signs of current or impending structural failures such as cracking. Lines do not have adequate capacity to pass peak flows (e.g., surcharging, SSOs, etc.).
Calculate the number of sections of pipe needed for repairs:
A sewer pipe has failed and 94 feet of 12 in vitrified clay pipe must be replaced. How many 4 foot sections are required?
Since the pipe comes in four foot sections, divide the total number of feet by 4 which represents the section length.
Sections required = (94 feet) / (4 feet) = 23.5 or 24 sections of pipe
Provide a description of the lift stations in the sewershed where the project will occur. For lift stations, utilize the following example definitions for Good, Fair, and Poor:
* Good – Pumps within the lift station show little signs of wear and function in an efficient manner with only routine maintenance. Equipment/appurtenances show minimal signs of corrosion. Lift station has needed reliability (e.g., standby power). * Fair – Pumps within the lift station show some signs of wear and fail periodically. Some repair outside of routine maintenance is required to keep the pump functioning. Equipment/appurtenances show signs of corrosion. Lift station may need minor upgrades to provide reliability.
* Poor – Pumps within the lift station show signs of wear and fail on a regular basis. Repairs outside of routine maintenance occur frequently. Equipment/appurtenances show excessive signs of corrosion that limit functionality. Lift station needs upgrades to provide reliability.