Collection
System Evaluation and Maintenance Program
RJN
Group, Inc.
The purpose of this project is to identify and repair system defects in the piping and structures of the main interceptors lying within the Edwards Aquifer Recharge Zone. This map indicates the general extent to which the developed areas and associated collection systems encroach on the Edwards Aquifer.
Safety Program
Because of the nature of our work, RJN field technicians have extensive experience working in confined space environments in hazardous sewers. The field staff is certified in first aid, confined space entry and Self Contained Breathing Apparatus (SCBA) usage. Our safety program will be submitted to SAWS prior to project initiation and will be strictly followed throughout the entire duration. Manhole Inspection The manhole inspection activity will require expertise to locate, uncover, and inspect the manholes. The project includes approximately 1,000 manholes to inspect.
1. Manhole Scouting
- Manhole "Scouts" are dispatched
to locate every manhole in the system. Once located, the crew
opens the manholes to confirm that it is the correct one. The
crew marks the lid and flow directions with paint and flag the
area and route to the manhole with survey tape. The crew fills
out a location report and records the GPs coordinates to make
it easier for subsequent crews to find the location. Each manhole
will be marked with paint to indicate that it has been inspected.
Maps will be corrected to reflect actual locations of access structures. Photographs will be taken of each identified defect including each incoming and outgoing pipe segment. All data will be reviewed in the office for quality control prior to being entered into the data management system. Televised Inspection Approximately 300,000 linear feet of sewer will be televised using pan and tilt cameras mounted on a crawler. It is anticipated that some inspections will be performed at night when flow depths are a minimum. However, we will consider the noise impacts to the local community.
RJN's approach employs technology to gather TV inspection data in digital format in the field capturing both video and audio in digital format. The technology can generate MPEG-1 video file format that is recognized by standard video compression software. Once the video is digitally captured and observations are logged, TV inspection data can be edited and verified for quality control. Attachments including design or as-built files, and maps or maintenance records can be viewed and printed. This significantly reduces the review time, while maintaining the quality and accuracy of the information obtained. All defects are recorded on voice narrative in the field and again verified in the office during the tape review process. Data Analysis and Design Recommendations The manhole and television inspection data will be used to develop the rehabilitation strategies. The strategy will include the evaluation of each type of defect, a rehabilitation method, and the costs associated with the improvement based on local contractor bid schedules. Rehabilitation methods that will be evaluated for defect removal will include repairs for manholes, sewer mains and interceptors, and laterals. In addition, routing options will be considered for those segments that are on private property where open cut may prove impractical. Main line and interceptor rehabilitation methods will include conventional open cut and trenchless technologies. Lateral repairs include replacement, point repairs with emphasis on lateral to main connections, trenchless methods, and cleanout repairs.
Improvement Techniques
Options other than open cut replacement will be considered when developing the rehabilitation recommendations. Because the manhole rehabilitation and trenchless technology improvements require less design time, the construction process can be expedited through conventional bidding or through the term bid process. Therefore, where feasible and cost-effective the RJN Team will focus on incorporating trenchless technologies. Pipe Bursting
Pipe bursting is a cost effective alternative for increasing line sizes in areas where open cut is impractical. Generally, the only required construction is the creation of an access pit to insert the new pipe. Caution must be taken to account for excessive vibrations that may have an affect on surrounding buildings and structures. CIPP Cured in Place Pipe (CIPP) is a proven alternative to open-cut construction to restore the condition of a pipe and the structural integrity. The method requires minimal or no construction for the access pit and bonds to the host pipe forming a pipe-in-a-pipe. This technology may prove to be a viable option in congested areas or publicly sensitive areas that require minimal disturbance to the ground surface over the pipe. Manhole Rehabilitation A variety of manhole restoration techniques are available that involve the use of various compounds and materials. Some techniques are only suited for restoring the structural integrity of the manhole. Others provide little structural benefit, but are more effective to reduce and eliminate exfiltration. Some manhole restoration products actually degrade when in the presence of H2S gas, a natural byproduct of wastewater decomposition.
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