2 1-17 crafs prez without spec
- 1. CRAFS® (Corrugated Retention and Filtration System) The Sediment Retention Device (SRD) for Critical Spots with Trouble Conditions where Silt Fences Fail
- 2. Critical Spots with Trouble Conditions … Where Silt Fences Fail Problem = Build Up of Retained Runoff
- 3. Silt Fence Problems - very slow to no seepage - overflow, knock down, and scour beneath /////////////////////////////////////////////////////////////////////////////// Conventional Solutions … Limit Buildup Silt Fence J-Hooks Silt Fences in Series ///////////////// OR ///////////////// Crushed Stone “Control Outlets” (i.e., Reduced Flow Rate at Select Locations) But NO “Sediment Retention and Filtration”
- 4. The CRAFS® Alternative at Critical Spots with Trouble Conditions for Retention and Filtration
- 5. CRAFS® Eliminates Blunt Impact UPSTREAM support post(s) “SPLITS” runoff entering system . … runoff flows diagonally toward DOWNSTREAM support posts
- 6. CRAFS® DIVIDES & DISTRIBUTES retained runoff into multiple retention wedges for … lower stress on retention system, … broader sediment “deposition” upstream , and … more filter fabric surface area against retained runoff
- 7. Heavy loads of retained runoff = Instability and Overflow CRAFSTM 3-D Structure = “Lateral Load Support” CRAFS® Lateral Load Support … with interaction between upstream and downstream support posts
- 8. … stability within corrugated structure … support to adjacent silt fences CRAFS® Lateral Load Support means …
- 9. CRAFS® Filter Cake Cleansing Runoff Washes “Filter Cake … Rejuvenates Faster Filtered Seepage ! … see top lines of “unwashed filter cake” on fabric from prior runoff events … filter cake below “top lines” has been washed away by subsequent runoff
- 10. CRAFS® Faster Filtered Seepage More Filter Fabric Surface Area = Faster Filtered Seepage ... less chance of overflow, knock down, and scour beneath sediment retention device
- 11. ^ Immediately following sediment slurry into systems ^ ^ One hour after slurry retention ^ (>4 hr) (1 ¼ hr) ^ Total time for dewatering ^ SLURRY RETENTION AND FILTRATION TEST Linear System Corrugated System
- 12. CRAFS® ... the Problem Solver Eliminates Blunt Impact Divides and Distributes Lateral Load Support Filter Cake Cleansing Faster Filtered Seepage
- 13. The CRAFS® Alternative for sediment retention and filtration in Critical Spots with Trouble Conditions … more structural stability and faster filtered seepage at outlets, inlets, and other localized problem areas.
- 14. CRAFS® INSTALLATION 1. Clip banding at top & bottom of packaging, slide CRAFS® from fabric sleeve, and unroll CRAFS® system with nonwoven fabric apron against the ground and woven monofilament filter fabric atop apron. 2. Pull all four corners of system’s apron taught with bottom of apron against ground surface. Upstream edge of apron should extend 12” upstream of the “stake sleeves” for the system’s “vertical filter fabric component”, and be parallel with alignment of toe-in trench. 3. Dig toe-in trench for CRAFS® in straight line perpendicular to the direction of flow for sediment runoff. If CRAFS® is adjacent to and connected with a silt fence alignment, toe-in for both systems will follow the same trench alignment perpendicular to direction of sediment runoff. 4. Because CRAFS® is intended for critical spots with trouble conditions, proper apron “toe-in” is critical. Assure apron “toe-in fabric” is placed against the downstream vertical wall of 6” deep “toe-in trench” (adjacent to system’s upstream vertexes), and laid across the bottom of the “toe-in trench” full 6” width. (See Step 8 below regarding compaction of toe-in backfill.) 5. Slide fence posts through sleeves at the upstream vertexes of system, and drive vertically through the apron fabric in bottom corner of trench, until post stands stable. 6. Pull down stream edges of apron taught and assure apron lays flat against the ground surface. Slide fence posts through sleeves in downstream vertexes, and pull taught in perpendicular direction against upstream post alignment. Drive downstream posts vertically into the ground while maintaining through fabrics between all posts in system (upstream and downstream), i.e., to eliminate wrinkles in the “vertical corrugated filter fabric system” as well as the apron lying on the ground. 7. While assuring vertical posture of all posts and “no slack” in system’s fabrics, firmly drive all upstream and downstream support posts “firmly” into the ground. 8. Provide “firm” compaction of all backfill in “toe-in trench”, and assure elevation of densely compacted backfill is same or slightly higher than adjacent native soil level. Add and compact more backfill if necessary. 9. Confirm vertical posture of support posts, and be sure that all other steps of post and toe-in installation are completed per ASTM D6462 Section 8.2 “Construction”. Make corrections if necessary to assure system stability and long term performance after installation. 10. For routine inspection and maintenance of CRAFS® units installed, follow the general guidelines provided in ASTM D6462 Section 8.3 “Maintenance”.
- 15. CRAFS® SRD SPECIFICATIONS CORRUGATED RETENTION & FILTRATION SYSTEM) Spec sheet details omitted … but available on request cea.geosyn@gmail.com Spec sheet details omitted … but available on request cea.geosyn@gmail.com
- 16. Spec sheet details omitted … but available on request cea.geosyn@gmail.com Spec sheet details omitted … but available on request cea.geosyn@gmail.com
- 17. /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Table 1: CRAFS® Fabric Property Requirements* PROPERTY TEST METHOD UNITS VALUE1 VALUE1 “Woven Monofil. “Needle-punched Filter Fabric” 2 Nonwov Fabric Apron” 2 /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// AOS ASTM D4751 U.S. Std Sieve #30 (max) #80 (nominal) Flow Rate ASTM D4491 gpm/sf 75 (min) 90 (min) Grab Tensile ASTM D4632 Strength lbs 260 X 180 (min) 200 X 200 (min) Elongation % 15 (nominal) 50 (nominal) Mullen Burst ASTM D3786 psi 175 (min) -- Trapezoid Tear ASTM D4533 lbs --- 80 (min) UV Resistance ASTM D4355 % 80% (4) 70% (4) /////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// FOOTNOTES: * Fabric Properties noted in Table 1 are the components of a Standard CRAFS® unit. CRAFS® units are available with alternative filter fabric and apron components if special conditions or performance requirements are deemed necessary by the project specifier. 1- Certifiable Min or Max 2- Woven Monofilament “Filter Fabric” - Vertical System Component 3- Needle-punched Nonwoven Apron Fabric - Horizontal System Component 4- Strength retained after 500 hr UV exposure ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
- 18. Natl Transportation Product Eval Prog – AASHTO NTPEP-SRD Pilot Project Testing w/ CRAFS® … 6-8-16 Three rainfall intensities … mild to severe (2“, 4“, and 6" in/hr) Results Monitored … Runoff Volume & Turbidity, Cummul Soil Loss, Cummul R Factor, and Avg P Factor. CRAFS® Avg Retention Efficiency = 95 %
- 19. NTPEP-SRD Pilot Test (TRI Demo 10/2016 – full test abbreviated by “Very Brief” Rainfall Event) Note: Water levels upstream of SRD tested … CRAFS® provides much faster “filtered seepage for dewatering” retained runoff than “Specialty Silt Fence fabric”. ^ CRAFS® ^ ^ Specialty Silt Fence Fabric ^
- 20. … for runoff outlets and other problem areas. ... a new wrinkle for the old problems of sediment control = less overflow, knock down, and scour beneath CRAFS® … the Problem Solver