Updated National Survey of Current Practices on Trench Bedding, Embedment, Backfill and Shoring

Pipe materials used in underground water, wastewater, and storm drainage infrastructure are manufactured according to published national standards such as AWWA and ASTM. The pipe bedding, embedment, backfill, and shoring systems, however, vary regionally across the country. This is due to variations in native soil conditions, availability of pipe zone materials, and local pipeline contractor preferences. The varying regional practices often limit an engineer's ability to specify trench and shoring conditions without adequate knowledge of local practices. The task committee conducted a national survey in 2009 to document the varying regional practices across six different regions of the country. Due to limited participation, the survey did not generate a complete and comprehensive response of pipeline installation procedures across the country. In order to address this shortcoming, a revised national survey is being conducted by the task committee to collect existing data on specifications, standard details, design criteria, and material specific concerns with an aim to document regional variations of specifying and construction practices and constructability issues associated with local native ground conditions, including interaction between native ground and bedding, embedment, and backfills placed and compacted, testing requirements, use of waste or recyclable materials, sustainable materials, and construction methods such as use of varying types of trench boxes, sheeting and shoring systems. The survey is targeting various state Department of Transportation (DOT) or similar local jurisdictions, large municipalities, water or wastewater agencies, national engineering firms, national pipe suppliers, contractors, and pipe vendors. This paper presents the details of the improved and comprehensive survey currently being planned to be conducted in early 2013. A summary of the nationwide findings based on the improved and comprehensive survey will be presented during the Pipelines 2013 conference to be held in Fort Worth, TX, with the primary objective of soliciting feedback and collecting additional input.