ASTM D7701 - 11 standard test method for determining the flow rate of water and suspended solids from a geotextile bag
This test method may be used as an aid to design geotextile container systems that contain fine-grained, high water content slurries such as dredged materials to meet special environmental or operational requirements. This test is often used to demonstrate the efficacy of geotextile dewatering to regulatory agencies in determining the amount of dredged material sediment passing through a geotextile and the flow rate for specific high water content materials.
The designer can use this test method to assess the quantity of fine-grained dredged material sediment that may pass through the geotextile container into the environment.
This test method is intended for evaluation of a specific material, as the results will depend on the specific high water content slurry and geotextile evaluated and the location of the geotextile container below or above water. It is recommended that the user or a design representative perform the test because geotextile manufacturers are not typically equipped to handle or test fine-grained slurries.
This test method provides a means of evaluating geotextile containers with different dredged materials or high water content materials under various conditions. The number of times this test is repeated depends on the users and the test conditions.
This test method may not simulate site conditions and the user is cautioned to carefully evaluate how the results are applied.
1.1 This test method is used to determine the flow rate of water and suspended solids through a geosynthetic permeable bag used to contain high water content slurry such as dredged material.
1.2 The results for the water and sediment that pass through the geotextile bag are shown as liters of water per time period, and the percent total suspended solids in milligrams per liter or parts per million.
1.3 The flow rate is the average rate of passage of a quantity of solids and water through the bag over a specific time period.
1.4 This test method requires several pieces of specified equipment such as an integrated water sampler, analytical balance, geotextile container, frame to hold the geotextile container, and clean containers to collect the decant water and a representative sample of high water content material from the proposed dredge area or slurry source.
1.5 The values stated in SI units are to be regarded as the standard. The values in parentheses are provided for information only.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
contaminated dredged material; dredged material; flow rate; geotextile container; high moisture content slurry; suspended solids
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