Team Members and Resources
Mike Fritz / Brett Odgers - Contech / Keith Ferrell / Llans Taylor

(Rationale: Update outdated specification to the current AASHTO M288 standard with required modifications for clarity and consensus in use. Also deleted duplicate language between this specification and the current AASHTO.)

7/14/03 – Reviewed by Chief Engineer. Revised 1011.3.1.1 to be consistent with 1011.3.3.1.

9/16/03 – Added Sec 1011.3.5, Erosion Control Blanket specs, since it was recommended these be moved from Sec 806 by the EPSC at their 9/15/03 meeting. The Sec 806 spec team proposed to this provision from the supplemental job special provisions into Sec 806.90. Upon review, the EPSC determined that the addition was mainly material specifications and the provision should be incorporated into Sec 1011.

SECTION 1011

GEOTEXTILE

1011.1 Scope. This specification covers geotextile for use in subsurface drainage, sediment control, erosion control or as a permeable separator.

1011.2 Acceptance.

1011.2.1 Acceptance of the material will be based on the manufacturer's certification and upon the results of such tests as may be performed by the engineer.

1011.23 Material. Geotextiles shall be meet thein accordance with the physical and chemical requirements of AASHTO M 288 for the specified application, except as modified herein in this specification.

1011.2.1 General.

1011.2.1.1 No specific permeability values are required.

1011.2.1.2 The U. S. Standard sieve number corresponding to the apparent opening size (AOS) shall not exceed 100 (150 µm) for geotextile used in contact with any soil with more than 50 percent passing the No. 200 (75 µm) sieve nor shall the AOS exceed 70 (212 µm) when used between any two dissimilar granular material, less than 50 percent passing the No. 200 (75 µm) sieve, or when used to control movement of fines from a granular backfill through structural joints or into a drain pipe.

1011.2.1.3 During shipment and storage, geotextiles shall be protected from direct sunlight, ultra-violet rays, temperatures greater than 140 F (60 C), mud, dust and debris.

1011.23.21 Type 1, Subsurface Drainage Geotextile. Type 1 Subsurface drainage geotextile is shall be intended for used in subsurface drainage as a filter to protect drainage media from clogging with fines from adjacent soil. Typical applications will include lining of drainage trenches and wrapping drain pipes.

1011.23.21.1 The minimum permittivity shall be 1.3 0 sec-1.

1011.23.21.2 The material shall may be either AASHTO Class A2 or Class B unless otherwise specified.

1011.2.2.3 When material is furnished in the form of a knitted or woven sock to be stretched to fit snugly around perforated pipe, the grab strength requirements for AASHTO Class B applications may be reduced by 33 percent provided the minimum elongation is greater than 50 percent.

1011.23.32 Type 2, Temporary Silt Fence Sediment ControlGeotextile. Type 2 Temporary silt fence geotextile is intended for use shall be used in supported or non-supported sediment control fencing.

1011.23.43 Type 3, Permanent Erosion Control Geotextile. Type 3 Permanent erosion control geotextile is intended for usesshall be used when the erosion control measure will not be removed, such as erosion control of slopes and channels when placed under a rock blanket, rock ditch liner, etc.

1011.23.43.1 The minimum permittivity shall be 1.0 sec-1.

1011.23.43.2 The material shall may be either AASHTO Class A1 or Class B2. unless otherwise specified.

1011.23.54 Type 4, Separation Geotextile. Type 4 Separation geotextile is intended for useshall be used as a separation material to prevent mixing of dissimilar material and to control migration of backfill material through joints in structural elements. Typical applications include use between soil and select granular backfills behind retaining structures, box culvert joint wraps, placement behind mechanically stabilized earth wall facing panels, cover for drainage blankets and soil/rock fill separation in slide repairs.

1011.23.54.1 The minimum permittivity shall be 1.0 sec-1.

1011.23.54.2 The material shall may be either AASHTO Class 1 or Class 2.

high or medium survivability level unless otherwise specified.

1011.3.5 Erosion Control Blankets. Erosion control blankets shall be prequalified and categorized based on performance testing performed by the Texas Department of Transportation and the Texas Transportation Institute using the minimum standards cited in the Texas DOT Erosion Control Report “TXDOT / TTI Hydraulics and Erosion Control Laboratory Field Performance Testing of Selected Erosion Control Products Final Performance Analysis Through the Most Recent Evaluation Cycle”. Erosion control blankets shall meet the following requirements.

Class 1, Slope Protection
Type / Slope / Type of Slope / Maximum
Sediment
Loss / Minimum
Vegetation
Density
A / 3:1 / Clayey a / 0.34 / 80%
B / 3:1 / Sandy b / 12.20 / 70%
C / 3:1 / Clayey a / 0.34 / 80%
D / 3:1 /

Sandy b

/ 26.84 / 70%

a Clayey soil (AASHTO M 145, Type A-6 or A-7) is defined as soil having a minimum of 35 percent passing the No. 200 (75 µm) sieve and a minimum plasticity index of 11.

b Sandy soil (AASHTO M 145, Type A-1 or A-3) is defined as soil having 100 percent passing the No. 10 (2.00 mm) sieve and a maximum plasticity index of 6.

Class 2, Flexible Channel Liner

Type /

Duration

/

Shear Stress

/ Maximum
Sediment
Loss / Minimum
Vegetation
Density
E / Short-term (< 2 yrs) / 0-2 lb/ft [0-96 Pa] / 1.15 / 70%
F / Short-term (< 2 yrs) / 0-4 lb/ft [0-192 Pa] / 1.00 / 70%
G / Long-term (> 2 yrs) / 0-6 lb/ft [0-287 Pa] / 1.00 / 70%
H / Long-term (> 2 yrs) / 0-8 lb/ft [0-383 Pa] / 0.80 / 70%

1011.3.5.1 Anchors. Anchors as recommended by the erosion control product manufacturer shall be used.

1011.3.5.2 Test Methods. Erosion control blankets shall be tested and evaluated by the Texas Department of Transportation and the Texas Transportation Institute in accordance with the Texas DOT Erosion Control Report. The blankets will also be evaluated on the basis of their performance in the field.

1011.3.5.3 Prequalification. Prequalified procedures may be obtained by writing to the Texas Department of Transportation, Director of Construction and Maintenance, 125 East 11th Street, Austin, TX 78701-2483. A list of qualified erosion control blankets will be maintained by Construction and Materials. Erosion control blankets will remain on the list as long as field performance is satisfactory.

1011.34 Certification Documentationand Acceptance.

1011.34.1 The contractor shall furnish a manufacturer's certification to the engineer, for each lot of material furnished stating the name of the manufacturer, the chemical composition of the filaments or yarns and certifying that the material supplied is in accordance with this specification.conform to all requirements specified. The certification shall include or have attached typical results of tests from specific lots for all specified requirements.

1011.3.2 Acceptance of the material will be based on the manufacturer's certification and upon the results of such tests as may be performed by the engineer.

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