geotextile aos selection - chesapeake, virginia on the sieve analysis of the material to be retained...

CALCULATIONS Golder Associates Inc. 2108 W. Laburnum Avenue, Suite 200 Richmond, VA 23227 USA Tel: (804) 358-7900 Fax: (804) 358-2900 www.golder.com Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation This analysis is to determine the appropriate maximum Apparent Opening Size (AOS) for the geotextile component of the proposed leachate collection system. 1.0 ASSUMPTIONS The gravel drainage layer material consists of gravel corresponding to the gradation specification of the Virginia Department of Transportation (VDOT) #57 stone; and, The stone has a carbonate content of less than 15%. 2.0 CALCULATIONS 2.1 AOS Choice of apparent opening size (AOS) of a geotextile can be made using a variety of methods (Reference 2, Chapter 8). Since the purpose of the geotextile is to provide separation, the methods are based on the sieve analysis of the material to be retained (fly ash). A representative sample gradation analysis (sample ID# DPYT-SF-12) of fly ash from a similar project will be used for the AOS determination. 2.1.1 Task Force 25 Method Examine the percentage of soil passing the #200 sieve, then select AOS based on the following recommendations: Particles < 50% passing #200 sieve, AOS of the fabric > #30 sieve, or Particles > 50% passing #200 sieve, AOS of the fabric > #50 sieve. For sample DPYT-SF-12, the % passing the #200 sieve is 77.6%. Per the TF 25 method, select AOS as #50 sieve. 2.1.2 Giroud Method Based on the CU (coefficient of uniformity) criteria of the soil a flowchart for soil retention criteria under steady state flow conditions has been developed (Chart 1 from Reference 3). The path through the flowchart is illustrated on the attached Chart 1. From this, the minimum AOS selection is the #200 sieve. The more restrictive of these methods (Giroud) yields a minimum AOS of #200 sieve. Typical AOS of manufactured nonwoven geotextiles is no smaller than the #100 sieve. To compensate for the sieve size, a thick (heavier weight) geotextile is recommended to improve its filtration capacity. Date: August 29, 2013 Made by: DPM Project No.: 130-0193 Checked by: ATN Subject: Geotextile AOS Calculations Reviewed by: JRD Project: CHESAPEAKE ENERGY CENTER ASH LANDFILL - SWP #440 8232

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Page 1: Geotextile AOS Selection - Chesapeake, Virginia on the sieve analysis of the material to be retained (fly ash). A representative sample gradation analysis (sample ID# DPYT-SF-12) of

CALCULATIONS

Golder Associates Inc. 2108 W. Laburnum Avenue, Suite 200

Richmond, VA 23227 USA Tel: (804) 358-7900 Fax: (804) 358-2900 www.golder.com

Golder Associates: Operations in Africa, Asia, Australasia, Europe, North America and South America

Golder, Golder Associates and the GA globe design are trademarks of Golder Associates Corporation

This analysis is to determine the appropriate maximum Apparent Opening Size (AOS) for the geotextile component of the proposed leachate collection system.

1.0 ASSUMPTIONS

� The gravel drainage layer material consists of gravel corresponding to the gradation specification of the Virginia Department of Transportation (VDOT) #57 stone; and,

� The stone has a carbonate content of less than 15%.

2.0 CALCULATIONS

2.1 AOS

Choice of apparent opening size (AOS) of a geotextile can be made using a variety of methods (Reference 2, Chapter 8). Since the purpose of the geotextile is to provide separation, the methods are based on the sieve analysis of the material to be retained (fly ash). A representative sample gradation analysis (sample ID# DPYT-SF-12) of fly ash from a similar project will be used for the AOS determination.

2.1.1 Task Force 25 Method

Examine the percentage of soil passing the #200 sieve, then select AOS based on the following recommendations:

Particles < 50% passing #200 sieve, AOS of the fabric > #30 sieve, or

Particles > 50% passing #200 sieve, AOS of the fabric > #50 sieve.

For sample DPYT-SF-12, the % passing the #200 sieve is 77.6%. Per the TF 25 method, select AOS as #50 sieve.

2.1.2 Giroud Method

Based on the CU (coefficient of uniformity) criteria of the soil a flowchart for soil retention criteria under steady state flow conditions has been developed (Chart 1 from Reference 3).

The path through the flowchart is illustrated on the attached Chart 1. From this, the minimum AOS selection is the #200 sieve.

The more restrictive of these methods (Giroud) yields a minimum AOS of #200 sieve. Typical AOS of manufactured nonwoven geotextiles is no smaller than the #100 sieve. To compensate for the sieve size, a thick (heavier weight) geotextile is recommended to improve its filtration capacity.

Date: August 29, 2013 Made by: DPM

Project No.: 130-0193 Checked by: ATN

Subject: Geotextile AOS Calculations Reviewed by: JRD

Project: CHESAPEAKE ENERGY CENTER ASH LANDFILL - SWP #440

8232

Page 2: Geotextile AOS Selection - Chesapeake, Virginia on the sieve analysis of the material to be retained (fly ash). A representative sample gradation analysis (sample ID# DPYT-SF-12) of

Geotextile AOS Calculations August 29, 2013 CEC Ash Landfill – SWP #440 2 130-0193

3.0 REFERENCES

1. Koerner, Robert M., Designing with Geosynthetics, Fifth Edition, 2005 2. Qian, Xuede, Koerner, Robert M., and Gray, Donald H, Geotechnical Aspects of Landfill Design and Construction, 2002. 3. Ten Cate Nicolon Corporation, Geotextile Filter Design, Application, and Product Selection Guide, 2002.

8233