Page 43 - Section4.2.1-SWPPPCutSheet-FiltrexxStormWaterBlanket

FilterSoxx TM course to enhance the movement of subsurface and/or runoff fow. As with other retaining walls, additional drainage systems may be installed behind the wall. Drainage requirements shall be addressed by geotechnical engineer and/ or hydrologist. An optional drainage layer is advisable in some situations, using 8 in (300mm) dia. FilterSoxx TM flled w/ pea gravel, #8 limestone or aggregate of equivalent size. Material is stacked in a vertical layer between existing soil & Vegetated retaining wall to facilitate drainage away from existing soil before entering structural fll, and to have area of emergency drain relief from runoff/subsurface fow. Benefts of using FilterSoxx tm include: accurate estimate of quantity of stone needed for drainage layer & keeping stone confned to permanent drainage layer.

Installation of Base Course: After initial excavation, fne-tuning of the base surface should commence. Use a laser-level to prepare the surface for the frst course of FilterSoxx TM . The surface should be free of roots and rocks that may interfere with the FilterSoxx TM or result in an uneven surface. The base surface should be level. After preparation of the base surface, place an 8 in (200mm) layer of granular material over the native material, including within any the trenched section. A layer of semi-porous geogrid may be necessary to separate the granular fll from the native soil. Application may be made manually, by excavator or by pneumatic blower. At courses where the construction drawings indicate that geogrid is required, the geogrid is laid down prior to placement of FilterSoxx TM and wrapped around the FilterSoxx TM fascia. After placing and compacting the base material the frst course of geogrid should be installed. Place approved geogrid over granular material and fasten with sod staples or ½ ft (150mm) rebar stakes to temporarily anchor the geogrid while commencing work. Once geogrid is anchored, install FilterSoxx ™ the required length horizontally & parallel to wall face. Fill Filtrexx ® FilterSoxx ™ in place; frst course will be installed at base of wall, or if present, in the trench. When installing geogrid, ensure it is laid fat over backfll. Pull back on geogrid to ensure good connection w/ FilterSoxx ™ fascia and to remove folds in material. Wooden 2 in x 2 in (50mm x 50mm) stakes or ½ in (12.5mm) rebar used to pin geogrid until backfll is placed over geogrid. Note: Geogrid type, strength and spacing will vary between manufacturers. Consult project engineer for requirements & specs. Place non-woven geotextile to separate native and structural backfll, apply structural backfll w/ excavator/pneumatic blower. Fill should be

placed and compacted using 6-12 in (150-300mm) lifts. Apply native backfll w/ excavator/pneumatic blower. Note: typical compaction of fascia when using 12 in (300mm) and 18 in (450mm) dia. FilterSoxx ™ will result in approx. 30% reduction in ht (8 in [200mm] and 12 in [300mm] lift, respectively). To reduce compaction, pressure can be exerted on geogrid to pull tight against fascia, reducing compaction and increasing ht.

Installation of Succeeding Courses: Successive courses will be set upon previous courses in a batter prescribed by the site engineer. Continue placing FilterSoxx TM , aggregate and native soil or backfll as needed. Hand compaction and weight of successive layers will compact the FilterSoxx TM . Estimate of fascia compaction is 30% but may be adjusted by the project engineer. Filtrexx ® Certifed tm Installers are trained to account for compaction in order to achieve specifed wall height.

Backfll Compaction: A Professional Engineer shall specify the backfll type and proctor tests should be conducted using standard ASTM testing procedures or equivalent feld procedures as directed by the Engineer. Compaction of materials will vary with soil type but typically, smaller lifts of material (less than 12 in [300mm]) will be easier to compact.

Final Seeding – CAP: The top of the wall or ‘cap’ requires a Temporary seeding or Storm water blanket. For specifcations and design for Temporary seeding and Storm water blanket see sections 1.7 and 2.1, respectively. Each of these applications will effectively join the Vegetated retaining wall system with any existing vegetation or terrain. Prior to seeding the top of Vegetated retaining walls, be sure that the upper layer of geogrid is buried to a minimum of 6 in (150mm). FilterSoxx tm can be used to complete the cap in combination with fnal seeding.

Regular inspections should be conducted that are within local, state and federal guidelines for water quality regulations. A minimum of 70% uniform cover for vegetation within 2 seasons should be targeted. Areas that lack vegetation should be spot seeded using a compost/seed mixture. After six months if 70% uniform cover of nurse crop has not occurred it is recommended that reseeding or remedial planting be preformed.