2019-086 - Laserfiche WebLink

Home Browse Search

Phase II. Research , Bowman will coordinate with the IRCDUS GIS dept. to extract record drawing information on the year, type, material, and history of pipe breakages/repairs. Days and dates of underground pipe repairs will be pursued to determine the frequency of occurrence. We will gather information on prior repair methods and acquire any photos, work orders, pipe coupons and field orders which might focus on the cause or causes of past pipe failures. For example, how was the failure discovered? What was discovered at the time of the initial response to the repair? Were failures localized at joints? If the actual pipe material as manufactured is suspected to be defective, this may raise a potential issue that may take a direction that is outside the scope of this work. This investigation excludes any legal activities associated with defective pipe stemming from the pipeline manufacture. Phase III. Site Investigation The Bowman team will conduct onsite site investigations to identify potential contributions / sources of corrosion. This will be a walk-through visual inspection of the existing corridor to investigate for potential external corrosion sources such as the presence of overhead power, gas mains, underground wireline utilities, etc. Additionally, a soft dig analysis of the vicinity of existing repairs is anticipated if they can be isolated by County Staff. This is intended to evaluate the condition of the existing main in the vicinity of known failure points for analysis of the type of external Corrosion evident (pitting or corrosion), and to determine potential adjacent sources of Corrosion. Continuity testing with County Staff is anticipated to verify wireline continuity, or potential loss locations. The engineer will conduct limited onsite analysis of potential short circuit, and ground connectivity (OHM resistivity) testing will be performed using a hand-held meg device during the on-site investigations. Subsurface Exploration: Geotechnical Engineering work is anticipated to evaluate corrosivity of soils including chemical analysis, pH, and other items that could contribute to corrosion of the pipe. This work will also conduct a "four - point analysis" to test for transient voltages. We are anticipating this work to be conducted in multiple locations to be determined based on pipeline history, Staff input, and site evaluations. Phase IV. Identify Potential Sources / Causes Bowman will Prepare a list of nearly 20 potential areas of concerns / sources which have the potential to contribute to the pipe's pitting or corrosion. This list will expand or collapse as research and data is evaluated, and will be generated from past experience, interpretation of site conditions, review of available records, and interviews with IRCDUS personnel who operate and maintain the pipeline. The list will be broken down into sub categories based on experience and subject matter. Each potential source / cause will be identified, explained as a potential contributor and then be ruled out or assigned to the next level of investigation.