ESBGU <br />Table 2. Recommended Signal Pole Foundation Depths <br />Drilled Shaft Diameter <br />Signal Pole Type Drilled Shaft Length (feet) <br />(inches) <br />SM1 36 13.0 <br />SM2 36 14.0 <br />SM3 36 15.5 <br />SM4 42 16.5 <br />RECOMMENDATIONS <br />The following recommendations assume the earthwork will be completed during <br />dry weather. We should be contacted in the event the work occurs in the winter or <br />late spring, so we can provide additional recommendations for wet-weather <br />construction. Construction during wet weather will require site preparation <br />techniques that reduce the risk of subgrade pumping. This includesusing thick <br />Base Aggregate sections (typically ±24 inches thick) underlain by a separation <br />geotextile in all building, pavement and construction access areas. The contractor <br />may still experience pumping problems in the summer if the subgrade has not <br />adequately dried. <br />Contractors should be provided a copy of this report to review the <br />recommendations for subgrade preparation and foundation construction. We <br />should be provided an opportunity to meet with the contractor prior to construction <br />to discuss the site conditions and the contractor’s approach to site preparation. <br />Material and Compaction Recommendations <br />Material specifications provided below refer to ODOT’s Oregon Standard <br />Specifications for Construction (ODOT, 2018a). <br />1.Base Aggregate, as defined herein, should consist of relatively clean ¾ or <br />1-inch minus, well-graded, crushed gravel or rock meeting the gradation <br />requirements defined in ODOT Section 02630.10 Table 02630-1. <br />2.Subgrade Geotextile should consist of a woven geotextile fabric meeting <br /> <br />the requirements in ODOT Table02320-1. We should be provided a <br />specification sheet on the selected geotextile for approval prior to delivery <br />to the site. <br />3.Compact all fine-grained and granular soils to a minimum of 95% relative <br /> <br />compaction. The maximum dry density of AASHTOT99 should be used <br />as the standard for estimating the relative compaction. Compact all <br />imported fill in loose lifts not exceeding 12 inches. Thinner lifts may be <br />required if light or hand operated equipment is used. Field density tests <br />should be run frequently to confirm adequate compaction. Areas of <br />Santa Clara Transit Center January 15, 2019 <br />Geotechnical Investigation 8 Project 2181060 <br />Eugene, Oregon Rowell Brokaw <br />