Single Geomembrane Covered With Water Specifications

This is a sample specification for a leak location survey of a single geomembrane covered with water and underlain by electrically conductive materials such as earth or concrete. It may not be applicable for other configurations. This section should be used as a guide, and not used verbatim. Please review the text carefully and make changes appropriate for each application. In addition to testing impoundments, ponds, and tanks it can be used to test for very small leaks in the critical sump areas of landfills prior to placing earth materials on the geomembrane, as is sometimes done. The water can contain dissolved salts or other water-soluble compounds. Leak location surveys are commonly performed in saturated brine solutions. This specification can be used to test geomembranes covered with a layer of earth materials or sediment if the layer is flooded with water. The leak detection sensitivity will be decreased so the leak detection sensitivity test in ASTM D7007 should be modified accordingly. Additional specifications are needed if the layer covers the side slope or contacts earth ground or both. Leak Location Services, Inc. (results@llsi.com) (210) 408-1241 will review your particular application and recommend any changes to the specifications if needed. SECTION 02777 GEOMEMBRANE LEAK LOCATION SURVEY OF SINGLE GEOMEMBRANE COVERED WITH WATER PART 1 – GENERAL 1.1 SECTION INCLUDES A. Requirements for performance of a geomembrane leak location survey using electrical methods for post-geomembrane installation performance for a single geomembrane covered with water and underlain by electrically conductive materials such as earth or concrete. B. The optimum performance of a geomembrane leak location survey using electrical methods requires the conductive media above and below the geomembrane to be electrically isolated from each other except through the leaks being located in the geomembrane. It is also necessary to have a continuous electrically conducting pathway through an electrically conducting material above the geomembrane, through the leaks, and through an electrically conducting media under the geomembrane. C. The leak location survey shall be conducted after water has been placed on the geomembrane liner to detect leaks resulting from inadequate installation or other activities on the geomembrane. 1.2 RELATED SECTIONS A. Section ________ – Geomembrane B. Section ________ – 1.3 REFERENCES A. ASTM D6747 – Standard Guide for Selection of Techniques for Electrical Detection of Potential Leak Paths in Geomembranes B. ASTM D7007 – Standard Practices for Locating Leaks in Geomembranes Covered with Water or Earth Materials 1.4 SUBMITTALS Leak Location Contractor shall submit a Leak Location Survey Work Plan to Engineer for approval prior to commencement of the leak location survey. The Leak Location Survey Work Plan shall include: 1. Qualifications of Leak Location Contractor to include the number of years Leak Location Contractor has performed the survey method; 2. Resumes of on-site supervisors; 3. Description of the survey method, and procedures; 4. Required site preparations; 5. Estimated duration of survey; 6. Quality control and field calibration procedures; 7. A list of projects demonstrating the qualifications and experience where Leak Location Contractor and leak location supervisor has met the requirements of paragraph 2.1 of this section. 8. Sample of a final report (per ASTM D7007) provided by Leak Location Contractor following the completion of the survey. 1.5 CONSTRUCTION QUALITY ASSURANCE A. The leak location survey shall be observed by CQA Consultant. B. Contractor shall be aware of the leak detection activities outlined herein and shall account for these activities in the construction schedule. PART 2 – PRODUCTS 2.1 LEAK LOCATION CONTRACTOR AND SUPERVISOR QUALIFICATIONS Leak Location Contractor shall have qualifications and experience in conducting the survey method including having tested a minimum of 15,000,000 square feet of geomembrane liner within the previous three years. In addition, the leak location surveys must be supervised by a professional or technician with a minimum of three years and 1,000,000 square feet of geomembrane testing experience using the leak location survey method. The leak location supervisor must be on site full-time during the performance of the leak location survey. A qualified Leak Location Contractor is Leak Location Services, Inc. tel. (210) 408-1241. PART 3 – EXECUTION 3.1 INFORMATION REQUIRED CQA Consultant shall provide Leak Location Contractor with drawings showing: 1. All layers constituting the lining system. 2. Details of all geomembrane penetrations. 3. Peripheral details, including welds to adjacent lining systems. 4. Structures and obstructions above the geomembrane. 5. Electrical equipment above the geomembrane. 3.2 SITE PREPARATION A. Leak Location Contractor will identify actions required by Contractor to prepare the site for the leak location survey. B. Electrically conducting paths through or around the geomembrane to the conducting material under the geomembrane should be isolated if practical. Such ground paths include metal pipe penetrations, batten strips, grounded equipment or structures in the water, and an earth material layer or earth material ramp bridging from the water to earth ground. (Some isolation measures can be easily implemented during the construction. Other measures should be addressed in the design, or a statement should be made acknowledging that the survey will not be possible adjacent to these conducting paths, and overall leak detection sensitivity will be diminished.) 3.3 EXECUTION A. Leak Location Contractor shall inspect the site prior to commencing the survey to ensure all site preparations are completed and the site conditions are appropriate for conducting the leak location survey. B. Any discrepancy in the required site preparations described in the Leak Location Survey Work Plan or site conditions shall be reported to Contractor for corrective or appropriate action. C. After the water is placed on the geomembrane, conduct a leak location survey of the flooded area using the procedures for surveys with earth materials covering the geomembrane described in the latest version of ASTM Standard D7007. D. Leak Location Contractor shall inform CQA Consultant and mark the locations of all identified or indicated leaks with weights connected to floats with string, or written coordinates. 3.4 REPORTING Provide a written report within 14 calendar days of completion of the leak location survey field work as described in ASTM D7007. END OF SECTION