1. Construction Inspection for FO Activities - Geosynthetics
Geotextiles
Geogrids
Geocell
Geosynthetics
Geocomposites
Geosynthetic Clay Liners
Geomembranes

2. Geosynthetic
A planar product manufactured from polymeric material used with soil, rock, earth, or other geotechnical engineering related material as an integral part of a man-made project, structure, or system.

3. NRCS Guidance on Use of Geosynthetics
Construction Inspection for FO Activities - Geosynthetics
NRCS Guidance on Use of Geosynthetics
Design guidance – Design Note 24
Limitations on use – Unwritten policy on not using in dams
Future guidance – Draft TR-60 discusses the use of geosynthetics in embankments and foundations of dams
Other uses and design guidance from manufacturers
Geosynthetics are not mentioned in NEM or any NEH materials at this time. They are mentioned in CPS for pond liners, waste facility covers, and lined waterways and outlets. Design Note 24 is only written guidance on uses and materials and only deals with a portion of geosynthetics (geotextiles). Unwritten policy has been to not use geosynthetics in dams, but the draft TR-60 which is the bible for design of dams (not ponds) discusses allowable uses of these materials. Most of the design guidance and potential uses are driven by manufacturers.

4. NRCS Applications
Geotextiles - significant use Separation/Filtration for erosion protection Padding beneath Geomembrane liners Silt Fence Drainage Soft Foundation Reinforcement Reinforced Fill
Geomembranes - growing use Animal Waste and Irrigation Pond Liners Animal Waste Pond Covers Canal Liners

5. NRCS Applications
Geosynthetic Clay Liners - growing use Animal Waste Pond Liners
Geogrids - minimal use Soft Foundation Reinforcement Reinforced Fill Segmental Retaining Walls
Geocells - some use Load support Earth Retention Slope Protection

6. NRCS Applications
Geocomposites - minimal use Drainage behind retaining walls Drains in dams - chimney or seepage diaphragm

7. NRCS Applications Geotextiles Geomembranes Geosynthetic Clay Liners
Geogrids
Geocells
Geocomposites

8. Geotextile A permeable geosynthetic comprised solely of textiles
Non-woven or woven
Non-woven can be heat bonded or needle punched

9. Non-woven Geotextiles Separation/Filtration for erosion protection
Construction Inspection for FO Activities - Geosynthetics
Non-woven Geotextiles Separation/Filtration for erosion protection
Probably the #1 use of geotextile is in place of filter/bedding for riprap and other aggregates. The geotextile allows movement of water from the sides and bottom of the basin into the basin while retaining soil particles in place. Also keeps soil in place during pipe flow events due to velocity of water jet in basin. Eliminates the need for multiple graded filters to maintain soil in place.
3” sand layer under non-woven geotextile added due to geotextile plugging by fine sands

10. Non-woven Geotextiles Typical installation as filter for riprap
Construction Inspection for FO Activities - Geosynthetics
Non-woven Geotextiles Typical installation as filter for riprap
A typical installation detail for riprap and geotextile installation for wave erosion protection on a small dam. Note the installation trench for the geotextile on the top and bottom of the slope.

11. Sand Layer Used to Eliminate Clogging Problem with Problem Soils
Construction Inspection for FO Activities - Geosynthetics
Sand Layer Used to Eliminate Clogging Problem with Problem Soils
Non-woven Geotextile
Most often a non-woven, Class I material is specified. It may also be specified by weight, Class 1 ~ 8 oz/yd, Class II ~ 6 oz/yd and Class III ~ 5 oz/yd
Clean, packed sand under geotextile

12. Non-Woven Geotextile Keys to proper installation
Construction Inspection for FO Activities - Geosynthetics
Non-Woven Geotextile Keys to proper installation
Subgrade preparation is key
No rocks, clods, holes, depressions
Subgrade to +/- 0.1 ft is typical tolerance
Rock or clods smaller than 0.1’ allowed
Typically use fill sand or concrete sand
Compact sand with plate vibrator to provide firm base
No standing or flowing water
Subgrade preparation is key to get good contact between the geotextile and the subgrade. Depending on site conditions, an earthfill subgrade may be adequate. It must be firm yet allow smoothing with equipment or by hand tools. A 3” layer of concrete or fill sand is often used to account for poor soil conditions and provide a good contact surface for the geotextile. Placement in water is not recommended but may be allowed. Geotextile will normally “float” until weighted down with rock or other material.

13. Non-woven Geotextile Keys to proper installation (continued)
Construction Inspection for FO Activities - Geosynthetics
Non-woven Geotextile Keys to proper installation (continued)
If filtering is primary goal, then…
Geotextile should be sewn with a 6-inch overlap
No punctures or tears are allowed to secure the geotextile to the subgrade
Place loosely on the subgrade without stretching
Secure temporarily with single stones or crushed rock
Care should be taken to avoid damage during placement
Factory or field sewing of the overlaps is acceptable. If done at the factory, then geotextile will come in one big piece and be folded and rolled as needed to transport. Unroll and unfold as needed to place the geotextile in its final position without dragging across the subgrade. Do not use pins or stakes to secure the geotextile to the subgrade. Do not drop material more than 3’ onto geotextile.

14. Non-woven Geotextile Keys to proper installation (continued)
Construction Inspection for FO Activities - Geosynthetics
Non-woven Geotextile Keys to proper installation (continued)
If erosion control/separation is primary then…
Field overlap is allowed
Typically secured with pins provide by supplier
Place loosely on the subgrade without stretching
Care should be taken to avoid damage during placement
On long slopes, trenching at intervals may be required
Field overlaps shall be at least 18”. Unroll and unfold as needed to place the geotextile in its final position without dragging across the subgrade. Use approved pins to secure the geotextile to the subgrade. Do not drop material more than 3’ onto geotextile. Trenching may be used on slopes to insure that water does not follow the geotextile and erode subgrade material.

15. Woven Geotextiles Silt Fence
Construction Inspection for FO Activities - Geosynthetics
Woven Geotextiles Silt Fence
Silt fence has its own classification in the latest national material specification. Deposition from slowing down water, not from filtering.

16. Woven Geotextiles Typical installation of Silt Fence
Construction Inspection for FO Activities - Geosynthetics
Woven Geotextiles Typical installation of Silt Fence
Note the anchor trench and silt fence configuration in trench. Posts are installed with fence and may come pre-attached to fence.
If installed with fence plow, no trench or staples but depth of installation is usually 8-12 inches. Posts are installed after fence.

17. Woven Geotextile – Silt Fence Keys to proper installation
Construction Inspection for FO Activities - Geosynthetics
Woven Geotextile – Silt Fence Keys to proper installation
Proper location is key
Installed below grade
Minimum of 6” in trench or 8” with plow
Stapled in bottom of 6” x 6” trench
Posts on 8’ spacing or closer
Locate the fence approximately 5’ – 6’ beyond the toe of slope. Install along the contour line with a shot section turned upgrade at each end of barrier. Posts and wire supports on downhill side of fence. Posts should be 2”x2” nominal at least 4’ long.

18. Geotextile Drainage & Filtration
Construction Inspection for FO Activities - Geosynthetics
Geotextile Drainage & Filtration
Another use not typical of NRCS would be for filtration in the bottom of a detention pond or sediment basin. Allows water to move into the soil but retains sediment particles.
This is a repair of a land slide area caused by wet soils on the hill sides. The geotextile and drain material are installed to capture the water flowing from the hillside and safely moving it to a drainage system. The soil materials from the slide are being replaced to the nearly original location.

19. Geotextile Soft Foundation Reinforcement
Construction Inspection for FO Activities - Geosynthetics
Geotextile Soft Foundation Reinforcement
Another use not typical to NRCS. Geogrids are sometimes used for the same application.

20. NRCS Applications Geotextiles Geomembranes Geosynthetic Clay Liners
Geogrids
Geocells
Geocomposites

21. Construction Inspection for FO Activities - Geosynthetics
Geomembrane
An essentially impermeable geosynthetic composed of one or more synthetic sheets
Geomembranes are becoming more common for waste storage facilities as both liners and covers

22. Geomembrane Animal Waste Pond Liners
Construction Inspection for FO Activities - Geosynthetics
Geomembrane Animal Waste Pond Liners
Liners are used where soil conditions preclude the use of compacted soil liners. Local laws and regulations may also require their use for certain facilities (ie swine operations).

23. Geomembrane – Waste Pond Liner Keys to proper installation
Construction Inspection for FO Activities - Geosynthetics
Geomembrane – Waste Pond Liner Keys to proper installation
Proper subgrade preparation, similar to geotextile
Smooth slopes, no rocks or clods
If keyed in a trench at the top, some venting may be required
Installed by supplier or manufacturer
If very large, may be seamed or welded on site
Care must be taken around openings for pipe inlets, etc
Subject to damage by equipment or animals
Provide for cleanout of pond
A geotextile is often used for a cushion beneath the geomembrane because of unsuitable soils. A soil cover is recommended to protect from animal damage especially prior to use. Venting is required if no soil cover, recommended for all membrane liners. Ask about hippoing?

24. Geomembrane Animal Waste Pond Floating Covers
Construction Inspection for FO Activities - Geosynthetics
Geomembrane Animal Waste Pond Floating Covers
Used to control odors and biogas emissions. Typically installed by supplier or manufacturer along with gas collection system. The gas collection system also can be used as perimeter anchors. Must provide measures for removal of accumulated precipitation.

25. Geomembrane Animal Waste Pond Submerged Covers
Construction Inspection for FO Activities - Geosynthetics
Geomembrane Animal Waste Pond Submerged Covers
Similar to floating covers except held in place by gas collection system. Precipitation remains on cover.

26. NRCS Applications Geotextiles Geomembranes Geosynthetic Clay Liners
Geogrids
Geocells
Geocomposites

27. Geosynthetic Clay Liner (GCL)
A manufactured hydraulic barrier consisting of clay bonded to a layer or layers of geosynthetic materials

28. Geosynthetic Clay Liners Animal Waste Pond Liners

29. Geosynthetic Clay Liner for Waste Ponds Keys to proper installation
Construction Inspection for FO Activities - Geosynthetics
Geosynthetic Clay Liner for Waste Ponds Keys to proper installation
Proper subgrade preparation, similar to geotextile
Smooth slopes, no rocks or clods
Recommended to key in a trench at the top
Installed by contractor or land owner
Can be stapled at overlaps
Subject to damage by equipment or animals
Provide for cleanout of pond
A GCL is very heavy and cannot be easily moved once it is laid. Unrolled from machine front while moving backwards. Can be unrolled by laborers from the top but should not be unrolled by gravity (rolling down the slope).

30. NRCS Applications Geotextiles Geomembranes Geosynthetic Clay Liners
Geogrids
Geocells
Geocomposites

31. Construction Inspection for FO Activities - Geosynthetics
Geogrid
A geosynthetic formed by a regular network of integrally connected elements with apertures greater than 1/4 inch to allow interlocking with surrounding soil, rock, earth, and other surrounding materials to function primarily as reinforcement
Note difference between biaxial and uniaxial pictures shown. Center picture is of a triaxial geogrid.

32. Geogrids EWP - Reinforced Fill
Construction Inspection for FO Activities - Geosynthetics
Geogrids EWP - Reinforced Fill
Road
Geogrids can be installed either vertical or horizontal. These are vertical installations. If exposed, must be UV tolerant.
Bi-axial Geogrid
1/4” Rebar

33. Geogrids EWP - Reinforced Fill
Construction Inspection for FO Activities - Geosynthetics
Geogrids EWP - Reinforced Fill
These are examples of horizontal installations. The geogrid may be the facing and reinforcing or it may be used with other facing materials and just be used an earth reinforcement.

34. Construction Inspection for FO Activities - Geosynthetics
Geogrids EWP – MSE Wall
Explain and define MSE – Mechanically Stabilized Earth. Give examples of typical uses.

35. Geogrid/Gabion Wall EWP - Headwall
Uni-axial
Geogrid

36. NRCS Applications Geotextiles Geomembranes Geosynthetic Clay Liners
Geogrids
Geocells
Geocomposites

37. Geocell
A product composed of polyethylene strips, connected by a series of offset, full depth welds to form a 3-dimensional honeycomb system

38. Geocells Load Support Systems
Watering Facility
Stream Crossing

39. Geocells Earth Retention
Construction Inspection for FO Activities - Geosynthetics
Geocells Earth Retention
Geocells are available in different colors to match the surroundings.

40. Geocells Slope Stabilization
Construction Inspection for FO Activities - Geosynthetics
Geocells Slope Stabilization
Note geocell pattern in compacted gravel fill material. Outer cells are filled with soil to allow planting of vegetation and provide a “green” appearance in the future.

41. Geocells Slope Stabilization – Wave erosion
Construction Inspection for FO Activities - Geosynthetics
Geocells Slope Stabilization – Wave erosion
Front slope of structure eroded by wave action. Originally designed with a vegetated sloping berm to reduce wave erosion, but not successful. Note the use of old tires as riprap. Rock riprap is not available locally and therefore not cost effective. Supplier suggested geocells filled with concrete as a cheaper option both to anchor the concrete and reduce the required depth of concrete. TRM was analyzed but not deemed effective due to UV degradation.
Eroded front slope of small watershed structure
Front slope has been shaped and geocells installed. Ready for installation of concrete.

42. Geocells Slope Stabilization – Wave erosion
Completed installation of concrete in geocells as a wave erosion berm on a small watershed structure

43. Geocells Keys to proper installation
Construction Inspection for FO Activities - Geosynthetics
Geocells Keys to proper installation
Proper subgrade preparation based on application
Subgrade may be earthfill, gravel base, or other material
May require a geotextile between subgrade and geocell
Installed by contractor or land owner
On slopes, anchor at upper end, then expand fully and anchor lower end. Anchors can be #4 rebar, inches long
Clip adjoining sections together
Installation drawings provided by designer or supplier
The geocells come in various sizes and sections. They are shipped compressed and are expanded on site to meet the site specific requirements.

44. Geocells Keys to proper installation (continued)
Construction Inspection for FO Activities - Geosynthetics
Geocells Keys to proper installation (continued)
Infill cells with proper materials
Infill may be soil, gravel, or concrete
If geocells are being stacked, infill each layer separately
Infill may be different within layer
On retaining walls, outside cells may be filled with soil. Cover cells while filling other cells with gravel, etc.
Overfill slightly and compact as required by design
Stay off geocell with heavy equipment, use hand directed compactors
The placement of infill materials can be accomplished using small equipment working on top of infill and spreading ahead of equipment. If adequate room, material can be delivered from the side and spread.

45. NRCS Applications Geotextiles Geomembranes Geosynthetic Clay Liners
Geogrids
Geocells
Geocomposites

46. Geocomposites
A product composed of two or more materials, at least one of which is a geosynthetic, void space for drainage.

47. Geocomposite WSP - Seepage Collection
Clay liner
Filter sand
Geocomposite

48. Geocomposite WSP - Seepage Collection
Construction Inspection for FO Activities - Geosynthetics
Geocomposite WSP - Seepage Collection
Geocomposite
ASTM C33 sand, 6 in. thick
CL, 4 ft. thick
Explain all items shown. Explain why a Geocomposite is being used. Possibly a perched water table on the uphill side of a waste storage pond. The sand and geocomposite capture the seepage and direct it to a drain at the bottom of the pond where is drained by gravity or pumped. This will maintain the integrity of the compacted clay liner.
18 in. overlap
Nonwoven geotextile
ASTM C33, Size 89 drain material
4 in. dia. slotted pipe

49. Construction Inspection for FO Activities - Geosynthetics
Identification
Identify teams and provide each with a group of numbered samples. Provide 10 – 15 minutes for ID. Presentation of results by each group. Instructors will assist with keeping scores of the teams and winning team announced.