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used to provide the highest level of protection. All of these limits have been used successfully, <strong>and</strong>compliance to these limits has not been known to result in appreciable structural damage. Allvibration limits referred to herein apply on the ground level <strong>and</strong> take into account the response ofstructural elements (i.e. walls <strong>and</strong> floors) to ground-borne excitation.The majority of project construction activities would employ open-trench construction methods toinstall the new backbone pipeline, distribution lines, cross-connections, <strong>and</strong> customer serviceconnections. After the pipelines are installed, the trench <strong>and</strong> pavement would be restored. Finally,the existing pipelines <strong>and</strong> connections would be ab<strong>and</strong>oned.Activities with the potential of generating perceptible vibration levels would include the removal ofpavement <strong>and</strong> soil, shoring, <strong>and</strong> the compacting of backfill after the new pipeline is installed. Theproposed project would, at times, bring construction activities within about 25 feet of sensitive l<strong>and</strong>uses along the project alignment. Table 6 summarizes typical vibration levels associated withvarying pieces of construction equipment at a distance of 25 feet.Equipment anticipated during project construction would include: backhoes, excavators, cranes,dump trucks, front end loaders, asphalt pavement grinders, boiler trucks, bypass pipes, asphaltpavers, concrete trucks <strong>and</strong> various passenger vehicles. Neither vibratory or impact pile driving areproposed as part of the construction of the project.A review of the proposed equipment <strong>and</strong> the vibration level data provided in Table 5 indicates thatvibration levels generated by the majority of proposed equipment would be equal to or below the 0.2in/sec PPV criteria used to assess the potential for cosmetic damage to buildings of normalconventional construction. <strong>Vibration</strong> levels from dropping heavy equipment (clam shovel drop) orthe operation of a vibratory roller at a distance of 25 feet could slightly exceed the 0.2 in/sec PPVcriteria. Theoretically, these potential exceedances could be up to one one-hundredth of an inch persecond PPV (0.01 in/sec PPV). However, at a distance of 26 feet, the levels are calculated to be lessthan the 0.2 in/sec PPV criteria. Sporadic events such as dropping of heavy objects, <strong>and</strong> the use ofvibratory rollers within 25 feet of residences should be avoided to the extent possible. The impactresulting from the project would be considered less-than-significant as vibration levels would notexceed the 0.2 in/sec PPV criteria established to evaluate the risk for cosmetic or structural damageto buildings. <strong>Vibration</strong> levels generated by construction activities would be perceptible indoors <strong>and</strong>may be considered annoying. However, planned construction hours are during the daytime, limitingthe possibility of annoyance during typical periods of sleep or rest, <strong>and</strong> would only affect a particularresidence for a brief period of time as construction activities occur in areas immediately adjoining theresidence.12