Answer Happy

Design the Filter Fabric (Geosynthetic system) so as to prevent soil from migrating into the system (retention criterion) as well as allowing water to pass through (permeability criterion). The geosynthetic system must survive the installation process (survivability criterion) as well as the life of the structure (clogging resistance criterion). The riprap on the slope is required to permit groundwater seepage out of the slope face, without erosion of the slope. The site is close to a recreation area with buildings. The riprap is to allow unimpeded seepage out of slope. Riprap consist of large stone (300mm to 900mm) that are placed by dropping from a backhoe. Seeps have been observed in the existing slope. The gradations of the three sand samples beneath the riprap is shown in Table 1. Native trees and shrubs ECM Riprap stones Row of large anchor rocks in toe trench 1 (v) Filter fabric Crushed stone .. 2 h) Source: Maine DEP Figure 1: Rip Rap System
Table 1: Gradations of the Three Representative Samples Beneath the Riprap System Sample C 96 95 Sieve Size (mm) 4.76 1.68 0.84 0.42 0.15 0.075 0.037 Percent Passing, By Weight Sample B 98 97 95 92 83 33 5 Sample A 95 93 90 88 67 25 8 83 70 60 30 3