Subcontractors

R: b) See response to Question 12.b above.QUESTIONS AND RESPONSES NO. 4I . Q: (TC) SECTION 31 23 13 -1 - 3 SUBGRADE PREPARATIONNo use of geosynthetics for undercut stabilization have been referenced orspecified. The use of geosynthetics for this purpose, high tensile moduluswoven geotextiles in particular, have been shown to reduce the thickness ofsuitable fill requirements for soft subgrade undercut and replacement by up tofifty percent (50%). In addition, the use of geosynthetics in this application hasbeen shown to assist in achieving the required compaction rates for select fillmaterials.R: Thanks for the information but no changes will be made to the Documents.2. Q: (TC) SECTION 31 23 16 - 1 - 4 EXCAVATIONNo use of geosynthetics for trench stabilization or drainage and filtration hasbeen specified. The use of geosynthetics for trench stabilization, high tensilemodulus woven geotextiles in particular, has been shown to minimizedifferential settlement along pipe lines and utilities, extending their useful life.Additionally, the use of nonwoven geotextiles for filtration and drainageapplications has been shown to reduce clogging and surface subsidence fromsoil piping in this application. Also, the use of geosynthetics in theseapplications has been shown to assist in achieving the required compactionrates for select fill materials.R: Thanks for the information but no changes will be made to the Documents.3. Q: (TC) SECTION 31 23 23 - 4 - 10 FILL AND BACKFILLThorough geosynthetic specifications are not given for fill placement,compaction and equipment travel on the geosynthetics. Most rubber-tiredvehicles can be driven at slow speeds, less than 16 km/h (10 mph) and instraight paths over an exposed reinforcement or stabilization geosyntheticwithout causing damage to the product. Sudden braking and sharp turningshould be avoided. Tracked construction equipment should not be operateddirectly upon a geosynthetic. A minimum fill soil thickness of 6 inches (15 cm)is required prior to operation of tracked vehicles over a reinforcement orstabilization geosynthetic. Turning of tracked vehicles should be kept to aminimum to prevent tracks from displacing the fill and damaging thegeosynthetic.R: Thanks for the information but no changes will be made to the Documents.4. Q: (TC) SECTION 31 23 60 - 1 MECHANICALLY STABILIZED EARTHENSLOPES PART 11.02.REFERENCES SUBPART A.5"Tensar Earth Technologies, Inc. "SIERRA Slope Retention System DesignGuidelines"" are a proprietary design and specification method that are used byTensar Earth Technologies, Inc. to create non-competitive productspecifications. The Referenced PART 1.02.A.4 "FHWA NHI 00-043" designmethod is not proprietary and the geosynthetic mechanical reinforcement05/14/08 02001-158A QR 4-4