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Section 02310 <br /> HORIZONTAL DIRECTIONAL DRILLING <br /> C. All sound barrier walls shall have a minimum surface weight of 3.5 to 4.0 lbs./sq.ft. <br /> D. The structures shall be continuous along their width and height with no gaps at the <br /> ground. <br /> E. Sound absorbing panels shall be installed on the upper 6 feet of the sound wall. <br /> 1. The panels shall be a minimum 2-inch thick and have a minimum Noise Reduction <br /> Coefficient, (NRC) rating of 0.85. <br /> 2. The panels should be covered with a perforated metal with a minimum 27 percent <br /> open area. <br /> 3. Panels shall be a minimum 24-inch wide. <br /> 4. A maximum 12-inch space may be used between panels that are 24-inch wide with <br /> up to an 18-inch gap for panels that are a minimum 36-inch wide. <br /> 5. Sound wall panels can be selected that have a combination of sound barrier and <br /> sound absorbing characteristics. <br /> 3.03 DRILLING FLUIDS <br /> The Contractor is responsible for determining the composition of the drilling fluids and <br /> maintaining the fluid composition for the application and soil conditions encountered. The <br /> composition of all drilling fluids proposed for use shall be submitted to the Construction <br /> Manager for approval. No fluid will be approved or utilized that does not comply with <br /> permit requirements and environmental regulations. The District reserves the right to <br /> conduct field tests of drilling mud properties to assess the performance of the Contractor <br /> relative to completing the crossing and minimizing the environmental impact of HDD <br /> operations, specifically the occurrence of inadvertent returns. <br /> Contractor shall maximize recirculation of drilling fluid returns and accurately and <br /> continuously measure the drilling fluid flow rate and standpipe pressure. Contractor shall <br /> provide solids control and fluid cleaning equipment of a configuration and capacity that can <br /> process surface returns and produce drilling fluid suitable for reuse. <br /> Driller's mud shall be managed so that it is contained on-site in equipment (e.g. tanks, <br /> treatment equipment, hoses) at all times. Contractor shall make all diligent efforts to <br /> minimize the amount of drilling fluids and cuttings spilled during the drilling operation and <br /> shall provide complete containment and prompt clean-up of all drilling mud overflows or <br /> spills. <br /> Walnut Grove Sewer Project(Conformed) 02310-12 SA0160401 <br /> March 2008 NAsa0160401\Specs\WG ConformOiv 2\02310.doc <br />