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~ i <br />(d) It is stated in the geotechnical report included with the application that Public <br />Service Company was consulted concerning the design provided for haul <br />road crossings over the pipeline easement. In order to satisfy the regulatory <br />requirements for an engineering demonstration, the Division could accept <br />either the documentation that the proposed haul road is acceptable to Public <br />Service Company, or a rigorous engineering evaluation. <br />The components required for a rigorous evaluation would be the maximum <br />external pressure that may be applied to the pipeline by the cover soil and <br />vehicle traffic (including an impact factor of 2 for the moving load), the <br />diameter and shell thickness of the pipe, the composition of the pipe and a <br />safety factor. Also it is not clear if the five foot thick haul road embankment <br />proposed for pipeline easement crossings will be applied to the existing <br />ground surface or if topsoil will be stripped prior to installation of the road <br />embankment. Since topsoil in this location is as much as 2 Ys feet thick, its <br />presence or absence in the haulroad cross section would have a significant <br />effort on the external load applied to the pipeline. <br />Response: Prior to the placement of the proposed 5 foot cap on top of the <br />haulroad crossing across the pipeline easement, the entire area would be <br />covered by a suitable subgrade road fabric and then capped with the five feet of <br />road material. All of the existing topsoil will remain in place and the Operator <br />proposes to construct an earthen bridge across the pipeline easement in the <br />vicinity of the proposed haul road crossings. As recommended in the PSCo letter <br />dated 21 October 1998, the proposed haul road crossings will be "pot holed" in <br />cooperation with PSCo to verify the pipeline depth prior to the placement of any <br />fill material in these areas. <br />Strain gauges can be used to monitor the pipeline and provide early warning <br />of stress accumulation allowing for mitigation prior to pipeline rupture. An <br />article on the use of strain gauges is attached for your reference. If the <br />applicant agrees to install the strain gauges and is able to gain the <br />cooperation of the pipeline operator, then an installation plan, (number and <br />location of strain gauge emplacements), a monitoring and reporting plan, and <br />a threshold criteria for mitigative action must be developed and submitted for <br />Division review and approval. It is the Division's understanding that a single <br />strain gauge emplacement is adequate to monitor approximately 200 linear <br />feet of pipeline (Mike Bukovansky), personal communication). Threshold <br />criteria for mitigation can be developed by considering that maximum <br />allowable stresses in the pipeline should not exceed 30 percent ofthe pipeline <br />steel specified minimum yield strength. If the pipeline operator refuses to <br />cooperate in the installation and monitoring of strain gauges, the applicant <br />could put together a proposal to monitor the pipeline easement through the <br />use of inclinometers, extensiometers or similar devises. <br />6 <br />