1018 14TH ST 2023-02-09 - Laserfiche WebLink

SHANNON WILSON,INC. 4.4.3 Segment A Temporary Excavation Slope We performed a slope stability analysis of the proposed temporary excavation slope behind the Segment A bulkhead (associated with removal of contaminated soil)to determine feasible slope angles within the in situ soil. Based on our analysis, a slope flatter than 2.5H:1 V should be used to prevent shallow failures. If a slope steeper than 2.5H:1 V is used,the Contractor should be prepared for the slope to ravel back to a more stable slope. It should be noted that the Contractor should be made responsible for the selection of the final excavation slope based on their planned construction approach and worker safety. 4.5 Viewing Platform Foundation Design The proposed viewing platform is located in Segment A, near Station 0+00 (see Figure 2). We understand that the structure is intended for pedestrian use. Based on discussions with MNE,we understand that open-end steel pipe piles would likely be used to support the structure. We developed soil parameters for use by MNE in the axial capacity evaluation of the proposed piles. The ultimate axial capacity of a pile is a summation of the skin friction along the side of the pile and the end bearing at the tip of the pile. Table 2 provides ultimate unit skin friction and ultimate unit end bearing to estimate the axial resistance of the open-ended steel piles. The ultimate skin friction can be determined by multiplying the pile perimeter area by the ultimate unit skin friction. The ultimate end bearing can be determined by multiplying the pile end area by the ultimate unit end bearing. Because of the very dense nature of the glacial soils at the site, we anticipate that the open-end pipe piles will become plugged after penetrating about 5 to 10 feet into the very dense glacial soils below elevation -25 feet. Therefore, we recommend using the entire base area of the pile (e.g., 1.77 square feet for an 18-inch-diameter pile) in the calculation for ultimate end bearing. We recommend that a FS of 2.0 be applied to the ultimate values to obtain the allowable pile capacity. We understand that MNE will perform lateral resistance analyses of the piles for the viewing platform using the computer program LPILE'LUS. Recommended soil parameters for LPILEPLus are presented in Table 2. 5.0 CONSTRUCTION CONSIDERATIONS The applicability of the design parameters that are recommended in Section 4.0 is contingent upon good construction practice. Poor construction techniques and methods may alter conditions 21-1-21761-003-R 1 fdocx/wp/c,p 21-1-21761-003 16