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

SHANNON 6WILSON,INC. and steel sheet pile bulkhead is about 1,200 feet long. The bulkhead was divided into four segments for discussion, based on the existing bulkhead structure type as shown in Figure 2. Based on information provided by MNE (2011), we understand that the bulkhead structure configurations within each segment are as follows: ■ Segment A (approximately Station -1+20 to+1+20) consists of a stepped bulkhead and includes the boat hoist structure. The rear(upper) wall consists of timber soldier piles, lagging, and a timber waler and tieback anchor system. The approximate spacing of the piles and anchors are 4 feet. The lower wall is similar but with fewer anchors and no waler system. Segment A connects at the north end to the existing 14°i Street Bulkhead ■ Segment B(approximately Station 1+20 to 2+60) is a single wall consisting of timber piles driven immediately adjacent to one another with a waler and tieback anchor system. The marina railway system is located in this segment. ■ Segment C(approximately Station 2+60 to 7+10) consists of a stepped bulkhead, the rear(upper)wall consists of timber piles driven immediately adjacent to one another with a waler and tieback anchor system. The lower wall consists of sheet piles and is located about 10 feet in front of the upper wall. ■ Segment D (approximately Station 7+10 to 11+15) consists of an upper timber soldier pile and lagging wall, with an exposed height of about 8 feet. A riprap slope is present in front of the wall. We understand there is a lower wall in some areas that is partially covered by the riprap slope. On average,the mudline immediately in front the lower walls is at about elevation 0 foot and slopes away at approximately 2.5 horizontal to 1 vertical (2.5H:1 V). The sloped area typically stops at about elevation -12 feet and levels out towards the west. Based on the 90 Percent Submittal by NINE (2014), we understand that the proposed bulkhead will consist of a single sheet pile wall with one row of anchors. The anchors will be secured to a continuous concrete deadman. The proposed bulkhead will have an exposed height of about 17 to 20 feet and will be located along approximately the same alignment as the existing timber pile bulkhead. Because of the slope in front of the bulkhead,the new sheet pile wall would effectively retain about 20 to 25 feet of soil. We understand that the 90 Percent Design Submittal was recently completed for Phase 1. Phase 1 includes bulkhead replacement for Segments A and B. Design for bulkhead replacement at Segments C and D will be performed at a later date. We understand that removal of contaminated soil will be performed concurrently with the construction of the new bulkheads in localized areas within Segments A and B. Dredging will be performed to remove contaminated 21-1-21761-003-R1 fdocx/wp/c1p 21-1-21761-003 2