2010-05-07_PERMIT FILE - C2009087 (45)

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• • • Recommended Installation Guidelines Subgrade'-The first installation step is to make sure that the subgrade is properly prepared. Once the subgrade has been verified to be properly graded and compacted and generally free of ruts and projecting stones or clods, the blanket can be deployed. Generally, normal construction equipment should not cause signif- icant rutting of the subgrade. Other Layers - In some systems, another material such as mulch may underlie the blanket and therefore be placed first. When situations require the blanket to be laid on top of another material, care must be taken to prevent disruption of or damage to the underlying materials. Never use normal construction equipment directly on top of blanket. Seeding - In temporary, degradable systems, seed is generally spread on or drilled or sprigged into the subgrade prior to unrolling of the blanket. Many long- term, nondegradable systems are unrolled, and filled with soil prior to seeding. Positioning and Anchoring -In all cases, each blanket should be unrolled as close as possible to its intended final position to minimize the need for dragging which can dislocate underlying materials or dig up or disturb the prepared subgrade and /or seeding. Staking, pinning or stapling blankets to secure their position is commonly done with a frequency and at the relative locations required to assure stability on the terrain in question. Wind - Large panels of blankets can be lifted up by gusts of wind if not properly secured. Deployed materi- als are most vulnerable prior to anchoring. Wind displacement can cause damage such as tearing or less obvious, but equally as problematic, damage such as loss of fibers. Identified damage should be patched. Liberal use of temporary weights such as dirt mounds or sandbags is the most common strategy to avoid wind pick -up. Field Joining and Anchoring Proper installation of blankets is critical. Blanket panels are joined side to side and end to end by overlapping or "shingling" in the direction of flow. Overlaps are typi- cally secured by staking, pinning, or stapling at regular spacings along the overlap. Longitudinal overlaps must be a minimum of 3" along the overlap length. Blanket ends may be spliced by overlapping 1' (in the direction of water flow) with the upstream blanket placed on top of the downstream blanket. This overlap should be anchored at 1' spacing across the width of the blanket. Typically blankets are anchored with 11 ga. U- shaped staples, 6" or 8" long depending upon the looseness or compaction of the soil. Proper anchoring of rolled blan- kets also includes the following practices: • Terminal trenches (typically 6 inches wide by 12 inches deep) are made at the top and bottom (crest and toe) of all covered slopes and at the end of all lined channels. • Intermediate trenches, or "check slots" (typically 6 inches wide by 6 inches deep) or two closely spaced rows of anchors may be used transverse to flows at intermittent points down a slope or along a channel to prevent continuous flows beneath the blankets. "Patterning" staking, pinning, or stapling of positioned blankets accomplishes uniform anchoring. The pattern depends on the steepness of the slope or channel as shown in staple guidelines. Penetrations It is important that at the point of all penetrations through a blanket additional anchorage be provided. The most common penetration involves a pipe or manhole around which the blanket can be easily cut to fit closely and subsequently anchored. Penetrations and other structure interferences are notoriously prone to concentrated erosion. Therefore, special attention to detail is necessary when any of these features are encountered. Repairs If a repair is required because the blanket has been accidentally damaged, a patch of the same base blan- ket type should be cut to fit over and sufficiently beyond the damaged area to permit joining to or anchoring through the parent blanket. Bad &l ng Blankets whicd' %Ve installed prior to seeding must be subsequently seeded and, when directed, backfilled with soil. These blankets must be of the blanket type, meaning they must have an open structure to facilitate soil filling. Typically, once seeded, same day backfilling is preferred. Depending on the system design, the cover soil may be a special topsoil or simply general backfill. In either case, consideration must be made for the proper placement of the soil layer to completely fill the blanket without overfilling (which may prevent germi- nation) or causing construction damage. For Installation Assistance: GREE - A M G R I C A 800 - 929 -2184 (760) 348 -7600 Fax (760) 348 -3097 www.greenfiix.com