1 Scope
NOTE This specification covers the selection, furnishing, and installation of geosynthetic materials used in civil site construction to perform the functions of separation, subgrade stabilization, filtration, subsurface drainage, reinforcement, asphalt paving interlayer, and bentonite containment. (1.1)
NOTE The geosynthetic family addressed here includes woven and nonwoven geotextiles, biaxial and triaxial geogrids, drainage geocomposites (a geonet drainage core bonded to one or two nonwoven geotextile filter layers), and geosynthetic clay liners (a sodium bentonite layer encapsulated between geotextile or geomembrane components). (1.2)
NOTE These materials are commonly placed beneath flexible and rigid pavements, beneath aggregate base courses, within and beneath earthwork fills, in retaining wall drainage zones, in utility trenches and French drains, as pond and cap liners, and as asphalt overlay interlayers. (1.3)
NOTE Geosynthetic function — not material type — governs every property requirement: a single nonwoven geotextile may serve separation on one project and filtration on another, and the controlling properties differ accordingly. (1.4)
1.5The Contractor shall select and furnish each geosynthetic by the function it performs and the property class required for that function, as scheduled on the drawings or specified herein.
NOTE The Contractor shall not substitute on the basis of trade name or generic description alone. (1.6)
NOTE Predecessor work — clearing, grading, structural fill, and subgrade preparation — is governed by
Earthwork, and the subgrade delivered by that work is the surface on which geosynthetics under this standard are placed.
(1.7) NOTE Successor work — aggregate base placement is governed by
Aggregate Base Course, and retaining wall drainage and structural reinforcement geogrid are governed by
Retaining Walls.
(1.8) 1.9Where this standard conflicts with the project geotechnical report, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
2 Referenced Standards
2.1Materials, testing, and installation shall comply with the latest adopted edition of each of the following standards unless a specific edition is cited.
2.2Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
| Standard |
Title |
| AASHTO M288 |
Geosynthetic Specification for Highway Applications |
| ASTM D4751 |
Determining Apparent Opening Size of a Geotextile |
| ASTM D4632 |
Grab Breaking Load and Elongation of Geotextiles |
| ASTM D4833 |
Index Puncture Resistance of Geomembranes and Related Products |
| ASTM D6241 |
Static Puncture Strength of Geotextiles Using a 50-mm Probe (CBR) |
| ASTM D4491 |
Water Permeability of Geotextiles by Permittivity |
| ASTM D4595 |
Tensile Properties of Geotextiles by the Wide-Width Strip Method |
| ASTM D6637 |
Tensile Properties of Geogrids by the Single or Multi-Rib Tensile Method |
| ASTM D4355 |
Deterioration of Geotextiles by Exposure to Light, Moisture and Heat (Xenon Arc) |
| ASTM D5321 |
Coefficient of Soil and Geosynthetic Friction by the Direct Shear Method |
| ASTM D4759 |
Determining the Specification Conformance of Geosynthetics |
| ASTM D5887 |
Measurement of Index Flux Through Saturated GCL Specimens Using a Flexible Wall Permeameter |
| ASTM D6766 |
Evaluation of Hydraulic Properties of GCLs Permeated with Potentially Incompatible Liquids |
| GRI GT13 |
Geotextile Seam Strength and Geosynthetic Test Methods (GT series) |
| FHWA-NHI-17-038 |
Geosynthetics Design and Construction Guidelines (NHI Course 132013) |
3 Submittals
3.1 Action Submittals
3.1.1The Contractor shall submit the following for the Engineer of Record's review prior to delivering any geosynthetic to the site:
- Product data for each geosynthetic, identifying manufacturer, product designation, polymer type, and the function and application class it satisfies
- Manufacturer's certified test report (CTR) for each roll lot, stating actual measured values (not minimum-average-roll-value catalog values alone) for every specified property, with the test method cited for each
- AASHTO M288 survivability class designation for each geotextile, with the supporting grab tensile (ASTM D4632), CBR puncture (ASTM D6241), and AOS (ASTM D4751) values
- Permittivity (ASTM D4491) and apparent opening size (ASTM D4751) for every separation, filtration, and drainage geotextile, related to the protected soil gradation
- Wide-width tensile properties (ASTM D4595) for reinforcement geotextiles and single- or multi-rib tensile properties (ASTM D6637) for geogrids, in both machine and cross-machine directions
- UV resistance documentation per ASTM D4355 demonstrating retained strength after the specified exposure period
- Interface friction angle per ASTM D5321 where the geosynthetic is placed on a slope steeper than 3H:1V or within a wall or reinforced fill
- For drainage geocomposites: geonet core transmissivity at the design normal stress and hydraulic gradient, and filter geotextile properties
- For GCLs: bentonite mass per unit area, hydrated hydraulic conductivity (ASTM D5887 or D6766), and panel and overlap dimensions
- Manufacturer's installation instructions, including overlap widths, seaming methods, repair procedures, and UV exposure limits
- Layout or seaming plan where panels are sewn or where overlaps are oriented to drainage flow
☑ Product data (per function and class)
☑ Certified test report per lot (ASTM D4759)
☑ Survivability class with supporting values (AASHTO M288)
☑ Permittivity and AOS (ASTM D4491 / D4751)
☑ Wide-width / rib tensile (ASTM D4595 / D6637)
☑ UV resistance (ASTM D4355)
☑ Interface friction angle (ASTM D5321) — slopes / walls
☑ Geocomposite transmissivity — drainage
☑ GCL hydraulic conductivity (ASTM D5887 / D6766)
☑ Manufacturer installation instructions
☑ Layout / seaming plan
3.1.2The Engineer of Record may require independent third-party verification testing on a portion of the submitted roll lots where the geosynthetic is critical to the assembly or where the project is subject to a public-agency quality program.
3.2.1The Contractor shall submit the following for record:
- Roll identification log correlating delivered roll numbers to the certified lot test reports
- Subgrade acceptance documentation confirming the subgrade was proof-rolled and accepted before geosynthetic placement
- Field repair log documenting the location and method of any field-repaired damage
☑ Roll identification log
☐ Subgrade acceptance documentation
☐ Field repair log
4 Quality Assurance
4.1The Contractor shall furnish geosynthetics produced by a manufacturer regularly engaged in the production of the specified product type and participating in a recognized manufacturing quality control program.
4.2Certified test reports shall report actual measured values determined in accordance with the test methods cited in the referenced standards, and conformance to specified minimums shall be evaluated per ASTM D4759.
NOTE A conformance statement that asserts compliance without reporting measured values is not an acceptable substitute for a certified test report. (4.3)
NOTE Reported geotextile strength values shall be minimum average roll values (MARV) unless a typical or maximum value is expressly identified as such. (4.4)
NOTE The minimum lot-testing frequency is one certified test report per manufacturer roll lot; the Engineer of Record may require a higher frequency on public-agency projects. (4.5)
4.6The Contractor shall not commingle rolls from different lots without maintaining roll-to-lot traceability through the roll identification log.
4.7A pre-installation conference shall be held before the first geosynthetic placement to confirm subgrade acceptance, overlap and seaming requirements, equipment access, and UV exposure limits.
5 Function and Material Selection
NOTE Geosynthetics are selected first by the function they perform; the material type, property class, and survivability class follow from that function. The functions addressed by this standard are: (5.1)
- Separation — prevents the intermixing of dissimilar soils, typically a coarse aggregate base and a fine-grained subgrade, so the aggregate is not contaminated and pumped into the subgrade under traffic.
- Subgrade stabilization — improves the load response of a soft or wet subgrade so that a working platform can be built and the base course can be compacted; it combines a separation function with a measurable improvement in bearing.
- Filtration — retains soil particles while allowing water to pass, preventing piping of the protected soil into a drainage aggregate or pipe.
- Subsurface drainage — conveys collected water within the plane of the geosynthetic, as in a drainage geocomposite wrapped against a wall or placed beneath a slab.
- Reinforcement — adds tensile capacity to a soil mass through soil-geosynthetic interlock or friction, as in a geogrid that confines an aggregate base or a high-strength geotextile in a fill.
- Paving fabric interlayer — placed in an asphalt tack coat, forms a moisture barrier and stress-relieving membrane that retards reflective cracking in an overlay.
- Containment (geosynthetic clay liner) — provides a low-permeability bentonite barrier for ponds, secondary containment, and caps where a low hydraulic conductivity is required.
5.1.1Select all geosynthetic functions required for this application.
☑ Separation
☐ Subgrade stabilization
☐ Filtration
☐ Subsurface drainage
☐ Reinforcement
☐ Paving fabric interlayer
☐ Containment (GCL)
5.1.2Select the geosynthetic type furnished for the selected function.
Woven geotextile (slit-film or monofilament PP)
Nonwoven geotextile (needle-punched PP/PET)
Nonwoven geotextile (heat-bonded PET)
Biaxial geogrid (PP)
Triaxial geogrid (PP)
Drainage geocomposite (geonet + nonwoven filter)
Geosynthetic clay liner (GCL)
5.1.3The Contractor shall not substitute a woven geotextile for a nonwoven geotextile, or the reverse, without the Engineer of Record's written approval, because the two have different governing property tables and hydraulic behavior.
5.1.4The Contractor shall not substitute a biaxial geogrid for a triaxial geogrid, or the reverse, without written approval, because the aperture geometry and the directional distribution of tensile capacity are not equivalent.
NOTE Polymer Selection (5.2)
NOTE Polypropylene is the dominant polymer for separation, stabilization, filtration, and paving geotextiles and for most stabilization geogrids, owing to its chemical resistance and low cost; polyester is used where higher tensile modulus or creep resistance is required for reinforcement. (5.2.1)
5.2.2The polymer shall be resistant to the range of pH and to the chemical constituents anticipated in the in-situ soil and groundwater for the design service life.
5.2.3Polyester geotextiles and geogrids shall not be used in soils with a pore-water pH below 3 or above 9 without manufacturer confirmation of chemical durability, because polyester is susceptible to hydrolysis at alkaline pH.
6 Geotextile Property Requirements
NOTE AASHTO M288 organizes geotextile property minimums by survivability class, which reflects the severity of the installation conditions, and by elongation, which determines whether the woven or nonwoven strength column governs. (6.1)
NOTE Survivability Class (6.2)
NOTE Survivability class accounts for the mechanical demands of placement — subgrade angularity, aggregate size, lift thickness, and construction equipment — not the in-service load. (6.2.1)
NOTE Class 2 is the default for typical site conditions; Class 1 is required for severe conditions and Class 3 is permitted only for mild conditions. (6.2.2)
6.2.3The Contractor shall furnish a Class 1 geotextile where angular aggregate larger than 2 in. is end-dumped directly onto the geosynthetic, where the subgrade contains rock or large debris, or where heavy tracked equipment operates with a thin cover lift.
6.2.4The Contractor shall furnish a Class 3 geotextile only where the subgrade is fine-grained and smooth, the cover aggregate is well-graded and placed by light equipment, and the Engineer of Record has accepted the milder class in writing.
6.2.5Select the AASHTO M288 survivability class for the installation conditions.
○ Class 1 (severe — rocky subgrade, heavy equipment, angular aggregate)
● Class 2 (typical — default)
○ Class 3 (mild — fine-grained subgrade, light equipment)
NOTE Strength Properties (6.3)
NOTE The applicable strength column depends on geotextile elongation at failure: a geotextile with elongation below 50% (typically woven) and one with elongation of 50% or greater (typically nonwoven) carry different minimum strength values for the same survivability class. (6.3.1)
NOTE Specifying a woven minimum strength against a nonwoven product, or the reverse, produces a non-compliant submittal even where the product is otherwise suitable; the elongation class shall be confirmed against the strength column applied. (6.3.2)
6.3.3Grab tensile strength shall be determined per ASTM D4632.
6.3.4Grab tensile strength shall meet or exceed the value scheduled for the survivability class and elongation class.
6.3.5CBR puncture strength shall be determined per ASTM D6241.
6.3.6CBR puncture strength shall meet or exceed the scheduled value for the survivability class.
6.3.7The grab tensile strength shall not be less than the following minimum average roll value for the selected survivability class.
○ 500 (Class 1)
● 400 (Class 2)
○ 250 (Class 3)
6.3.8The CBR puncture strength shall not be less than the following minimum average roll value for the selected survivability class.
○ 900 (Class 1)
● 495 (Class 2)
○ 250 (Class 3)
NOTE Hydraulic Properties (6.4)
NOTE Apparent opening size (AOS, also expressed as O95) is the geotextile opening size at which 95% of the openings are smaller, and it controls whether the protected soil is retained against piping while water still passes. (6.4.1)
NOTE An AOS that is too small relative to the soil clogs and impedes drainage; an AOS that is too large allows the protected soil to pipe through the fabric — both are common, long-term failures. (6.4.2)
6.4.3Apparent opening size shall be determined per ASTM D4751 and shall satisfy the soil-retention criterion for the protected soil gradation.
6.4.4For separation and filtration in soils with 50% or less passing the No. 200 sieve, the AOS shall not be larger than the No. 30 sieve (0.60 mm).
6.4.5For separation and filtration in soils with more than 50% passing the No. 200 sieve, the AOS shall not be larger than the No. 50 sieve (0.30 mm).
6.4.6Select the apparent opening size requirement based on the protected soil fines content.
● No. 30 sieve (0.60 mm) — soils with ≤ 50% fines
○ No. 50 sieve (0.30 mm) — soils with > 50% fines
○ No. 20 sieve (0.85 mm) — paving fabric
6.4.7Permittivity shall be determined per ASTM D4491 and shall exceed the permeability of the protected soil so that the geotextile does not impede flow across its plane.
6.4.8For separation and stabilization geotextiles, the permittivity shall not be less than 0.02 s⁻¹.
6.4.9For filtration and subsurface-drainage geotextiles such as French drain and trench-drain wraps, the permittivity shall not be less than 0.5 s⁻¹.
6.4.10Select the minimum permittivity for the geotextile function.
● 0.02 (separation / stabilization)
○ 0.10 (filtration, moderate)
○ 0.50 (subsurface drainage wrap)
NOTE Ultraviolet Durability (6.5)
NOTE Polypropylene geotextiles degrade rapidly under ultraviolet exposure, losing strength within weeks of being left uncovered on the subgrade. (6.5.1)
6.5.2The geotextile shall retain not less than 50% of its grab tensile strength after 500 h of exposure when tested per ASTM D4355.
6.5.3Select the UV resistance requirement.
● ≥ 50% after 500 h (standard, AASHTO M288)
○ ≥ 70% after 500 h (extended exposure)
7 Subgrade Stabilization
NOTE Stabilization is warranted where the subgrade is too soft to support construction traffic or to allow compaction of the base course, and the geosynthetic provides separation plus a measurable improvement in the working platform. (7.1)
NOTE The decision between a stabilization geotextile and a stabilization geogrid is driven by the subgrade strength: a geotextile is generally effective for soft subgrades, while very weak subgrades favor a geogrid because the aggregate interlocks into the apertures and develops confinement. (7.2)
7.3A stabilization geotextile is generally effective where the subgrade CBR is in the range of 1 to 3 or the undrained shear strength is in the range of 30 kPa to 90 kPa.
7.4A subgrade with a CBR below 1 generally requires a geogrid, a geogrid-geotextile combination, or a thicker stabilization lift; the selection shall follow the project geotechnical engineer's recommendation.
7.5The Contractor shall not rely on a geosynthetic to remedy a subgrade that has not been proof-rolled and accepted; the geosynthetic supplements an accepted subgrade and does not replace subgrade preparation under Earthwork. 7.5.1Indicate the subgrade strength governing the stabilization selection.
CBR 1–3 / shear 30–90 kPa (geotextile effective)
CBR < 1 / shear < 30 kPa (geogrid or combination)
CBR > 3 (separation only, no stabilization)
Per drawings
8 Geogrid Property Requirements
NOTE Geogrids carry load through the interlock of aggregate or soil within their apertures, so the aperture geometry and the in-plane stiffness govern performance as much as the ultimate tensile strength. (8.1)
NOTE Biaxial geogrids have square apertures and distribute tensile capacity primarily in two orthogonal directions; triaxial geogrids have a triangular aperture pattern that distributes radial stiffness more uniformly in all directions. (8.2)
NOTE Because base reinforcement loads are radial under a wheel, the directional distribution of stiffness is a design property and a biaxial and a triaxial geogrid of nominally similar rib strength are not interchangeable. (8.3)
8.4Geogrid tensile properties shall be determined per ASTM D6637 and reported in both the machine and cross-machine directions.
8.5The geogrid shall be a single integrally formed or welded structure with a uniform aperture and shall not be a knitted or woven product that relies on coating alone for rib junction strength.
8.6The aperture size shall be compatible with the nominal aggregate size of the overlying base so that the aggregate partially penetrates and interlocks with the apertures, generally an aperture between one and two times the aggregate D50.
8.6.1Select the geogrid configuration.
● Biaxial (square aperture)
○ Triaxial (triangular aperture)
8.6.2The geogrid tensile strength shall not be less than the scheduled value for the design direction; the value below is a typical class to be confirmed against the submittal.
8003000
Default: 1600 lb/ft
Per drawings
9 Drainage Geocomposite Requirements
NOTE A drainage geocomposite combines a geonet drainage core that conveys water within its plane with a bonded nonwoven geotextile filter that retains soil while admitting water, and it replaces a graded aggregate drainage layer in a thinner section. (9.1)
NOTE The two governing properties are the core transmissivity at the design normal stress and hydraulic gradient, and the filter properties that protect the core from clogging. (9.2)
NOTE A drainage geocomposite is most commonly used against retaining wall backs, beneath slabs, and behind below-grade walls; the wall drainage application is coordinated with
Retaining Walls and
Foundation Drainage.
(9.3) 9.4The geonet core transmissivity at the design normal stress and hydraulic gradient shall meet or exceed the design flow capacity determined by the Engineer of Record.
9.5The filter geotextile bonded to the core shall satisfy the AOS and permittivity criteria of this standard for the protected soil.
9.6The geocomposite shall discharge to a positive outlet; the Contractor shall connect the drainage core to the collector pipe or outlet structure with the manufacturer's transition fitting or an approved detail.
9.6.1The connection of the drainage core to the outlet structure shall be made as detailed.
Manufacturer transition fitting to perforated collector pipe
Wrapped connection to underdrain
Discharge to daylight outlet
Per drawings
9.6.2The core transmissivity shall not be less than the scheduled design value at the design normal stress.
10 Paving Fabric Interlayer Requirements
NOTE A paving fabric is a nonwoven geotextile saturated with asphalt tack coat and placed between an existing pavement and an asphalt overlay, where it forms a moisture barrier and a stress-relieving interlayer that retards reflective cracking. (10.1)
NOTE The fabric must hold enough asphalt to seal and to bond both lifts, and it must withstand the temperature of the overlay without melting; both the asphalt retention and the melting point are specified properties. (10.2)
NOTE The asphalt tack-coat application rate is the most common source of paving fabric failure: too little asphalt and the overlay debonds, too much and the fabric floats and the overlay shoves. (10.3)
10.4The paving fabric shall be a nonwoven polypropylene geotextile with a minimum mass per unit area of 4.0 oz/yd² (136 g/m²).
10.5The fabric shall have an asphalt retention of not less than 0.20 gal/yd² as reported by the manufacturer.
10.6The fabric shall have a melting point of not less than 300 °F (149 °C) so that it survives placement of the hot overlay.
10.7The apparent opening size of the paving fabric shall not be larger than the No. 20 sieve (0.85 mm).
10.8The asphalt tack coat shall be applied at the rate required to saturate the fabric and bond both lifts, within the range scheduled below.
10.9The Contractor shall not reduce the tack-coat application rate to control tracking.
10.9.1Select the paving fabric mass per unit area.
10.9.2Select the asphalt tack-coat application rate for the paving fabric.
0.20.3
Default: 0.22 gal/yd²
NOTE Coordination of the paving fabric interlayer and the overlay placement is governed in part by
Asphalt Paving; the fabric installation shall not proceed ahead of the overlay crew beyond the area that can be paved the same day.
(10.10) 11 Geosynthetic Clay Liner Requirements
NOTE A geosynthetic clay liner is a factory-manufactured hydraulic barrier consisting of a layer of sodium bentonite supported between geotextile or geomembrane components, which swells on hydration to form a low-permeability barrier. (11.1)
NOTE A GCL is specified where a low hydraulic conductivity barrier is required for ponds, secondary containment, or caps within the civil sitework scope; primary hazardous-waste and landfill-cell containment is outside this standard. (11.2)
11.3The GCL shall have a bentonite mass per unit area not less than the scheduled value and shall use sodium bentonite unless an amended or polymer-enhanced bentonite is required for the anticipated permeant.
11.4The hydrated hydraulic conductivity shall not exceed 5 × 10⁻⁹ m/s when tested per ASTM D5887, or per ASTM D6766 where the GCL will be permeated by a potentially incompatible liquid.
11.5The Contractor shall protect the GCL from premature hydration; a GCL that hydrates under confinement before placement shall be rejected.
11.5.1Select the GCL bentonite mass per unit area.
11.5.2Select the GCL hydraulic conductivity test basis.
● ASTM D5887 (index flux, water)
○ ASTM D6766 (site-specific permeant)
12 Testing
NOTE Material acceptance is based primarily on the manufacturer's certified test reports, supplemented by conformance verification at the frequency required by the Engineer of Record. (12.1)
12.2The Contractor shall provide one certified test report per roll lot reporting the actual measured values for every specified property.
12.3Conformance to specified property minimums shall be evaluated in accordance with ASTM D4759.
12.4Where the Engineer of Record requires independent verification, samples shall be taken from delivered rolls in the presence of the Engineer's representative and tested by an accredited laboratory.
12.5Geotextile field seams, where sewn, shall develop the seam strength required by GRI GT13 and shall be verified by testing a representative seam sample.
12.5.1Select the conformance testing basis.
● Certified test report per lot (manufacturer)
○ CTR plus independent verification on ≥ 10% of lots
13 Installation
NOTE Subgrade Preparation and Acceptance (13.1)
NOTE Geosynthetic performance depends on the surface beneath it: a geosynthetic placed over a loose, rutted, frozen, or contaminated subgrade underperforms regardless of its property class. (13.1.1)
13.1.2The subgrade shall be proof-rolled and accepted under Earthwork before any geosynthetic is placed. 13.1.3The subgrade shall be free of standing water, sharp protrusions, vegetation, frozen lumps, and debris that could puncture or hold the geosynthetic off the surface.
13.1.4The Contractor shall not place a geosynthetic over a subgrade that has not been accepted by the Engineer of Record or the geotechnical engineer.
NOTE Placement (13.2)
13.2.1The geosynthetic shall be unrolled in the direction of construction traffic and laid smooth and in continuous contact with the subgrade, without wrinkles, folds, or tenting.
13.2.2The geosynthetic shall be anchored against displacement by wind and traffic using pins, staples, or a continuous edge of cover material as the work advances.
13.2.3Cover aggregate shall be end-dumped onto previously placed aggregate and spread forward over the geosynthetic, and shall not be dumped directly onto the bare geosynthetic where a Class 1 survivability has not been provided.
13.2.4Construction equipment shall not operate directly on the geosynthetic; a minimum cover lift shall be maintained between equipment and the geosynthetic at all times.
13.2.5Geogrid shall be pre-tensioned or pulled taut and staked so that it is free of slack before cover aggregate is placed, because a slack geogrid does not engage the aggregate and provides no reinforcement.
NOTE Overlap and Seaming (13.3)
NOTE Overlaps transfer no tension and exist only to maintain separation continuity across the joint; where tension must cross the joint, a sewn seam or a continuous panel is required. (13.3.1)
NOTE Overlap width increases as the subgrade softens, because a soft subgrade deflects under load and a narrow overlap can separate and expose the subgrade. (13.3.2)
13.3.3Adjacent panels shall be overlapped not less than 12 in. (300 mm) on a firm subgrade with a CBR of 3 or greater.
13.3.4Adjacent panels shall be overlapped not less than 18 in. to 24 in. (450 mm to 600 mm) on a soft subgrade with a CBR less than 3.
13.3.5Adjacent panels shall be overlapped not less than 36 in. (900 mm), or shall be sewn, where the subgrade is very soft with a CBR less than 1.
13.3.6Overlaps shall be shingled in the direction of cover placement so that the leading edge is not caught and displaced by the spreading aggregate.
13.3.7Overlaps and seams shall not be located beneath concentrated wheel paths or at the low point of a drainage geocomposite; geocomposite overlaps shall be oriented shingled in the direction of water flow.
13.3.8Where seams are sewn, they shall use a polymer thread compatible with the geosynthetic and shall develop the seam strength specified under Testing.
13.3.9Select the panel overlap width for the design subgrade condition.
● 12 (firm subgrade, CBR ≥ 3)
○ 18 (soft subgrade, CBR < 3)
○ 24 (soft subgrade, CBR < 3)
○ 36 or sewn (very soft, CBR < 1)
NOTE Curves, Corners, and Penetrations (13.4)
13.4.1At curves and corners the geosynthetic shall be folded or cut and overlapped so that continuous coverage and the specified overlap are maintained, without gaps at the inside of the curve.
13.4.2At pipe and structure penetrations the geosynthetic shall be cut neatly to fit and the opening shall be reinforced with an overlapping patch of the same material.
NOTE UV Exposure and Damage Repair (13.5)
NOTE Geosynthetics left exposed degrade under ultraviolet light, so exposure between placement and covering shall be limited. (13.5.1)
13.5.2The geosynthetic shall be covered with the overlying material within 14 days of placement unless the manufacturer documents a longer permissible exposure for the specific product.
13.5.3Geosynthetic damaged during placement — torn, punctured, or contaminated — shall be repaired by placing a patch of the same material extending not less than the specified overlap beyond the damage in all directions, or the damaged panel shall be removed and replaced.
13.5.4The Contractor shall document each field repair in the field repair log.
14 Delivery, Storage, and Handling
14.1Geosynthetics shall be delivered in the manufacturer's original packaging, with each roll labeled with the manufacturer, product designation, lot number, and roll number.
14.2Rolls shall be stored off the ground on a clean, dry surface and shall be protected from ultraviolet light, precipitation, mud, chemicals, and temperatures outside the manufacturer's storage range.
NOTE The manufacturer's protective wrapping shall remain on each roll until the roll is installed, because the wrapping is the primary UV and contamination protection during storage. (14.3)
14.4Bentonite-bearing GCL rolls shall be protected from any moisture during storage and handling, because premature hydration ruins the product.
14.5Rolls shall be handled with a core pin or stinger bar and shall not be dropped, dragged, or lifted by slings that crush the roll.
15 Warranty
15.1The manufacturer shall warrant each geosynthetic against defects in materials and manufacture for the period specified below.
NOTE The warranty shall not cover damage resulting from improper installation, ultraviolet exposure beyond the specified limit, or chemical attack by a permeant not disclosed to the manufacturer. (15.2)
15.2.1Select the manufacturer's material warranty period.