3535 RIVERFRONT BLVD Geotech Report 2023-02-22

ISeptember 24, 2018 HWA Project No. 2015-061-21 I I The soils below the 3-acre park site are known to possess woody organics such as logs and stumps. Therefore, it is possible that obstructions, which cannot be penetrated, may be encountered during pile driving. If such an obstruction is encountered, the pin pile I should be removed or abandoned in place, and a new pin pile should be installed at least 6 inches away. Alternatively, if sufficiently shallow, the obstruction in the location of the pile could be excavated and the pile re-driven. If it is necessary to move a pile, the Istructural engineer should check and revise the design and pile location as necessary. As the pin piles are to be driven at specific locations to accommodate the picnic shelter I foundations, moving the pin piles to avoid obstructions may require the foundation pile caps be larger where obstructions are encountered. If expanded pile caps are not desirable, predrilling could be completed to penetrate obstructions. ITypically, the steel pipe piles will be delivered to the site in 21-foot (maximum) sections. Force-fit pin connections are typically used to splice sections together during installation. I The uplift capacity of the pin piles should be neglected,unless the pile consists of a single section of pipe, or the connection between sections are welded. IMat Foundation Option If the use of pin pile foundations is undesirable, the picnic structure could be supported Ion a mat foundation that is constructed with the ability to periodically relevel the shelter structure as settlement occurs over time. We expect that the releveling system would I likely consist of a series of heavy duty bolts extending from the mat foundation. The picnic structure would be mounted to these bolts with a series of plates and nuts. In the event of future settlement, the nuts could be turned to relevel the structure as needed. The I bolts would need to be installed with sufficient thread stickup to allow for releveling assuming the maximum anticipated settlement. For design of the releveling system, 3- to 5-inches of settlement should be assumed over the design life of the picnic structure. ITherefore, a minimum of 5-inches of releveling capability should be provided at each connection point between the picnic structure and the proposed mat foundation. IReleveling system details and design should be completed by a structural engineer. 4.5.3 Shallow Foundation Recommendation Outside the Surcharged Area I It is our understating that playground equipment and other lightly loaded structure may be installed as part of the 3-Acre Park project improvements. Due to geometry variability of the subgrade soils we anticipate 2 to 6 inches of differential settlement throughout the 50-year design Ilife of these lightly loaded structures founded on shallow foundation outside of the preload surcharged area. We recommend individual playground equipment be founded on single mat I foundations independent of the adjacent structures. We recommendation these foundation slabs to be equipped with a re-leveling attachment to re-level the foundation once excessive I Final Geotechnical Report-3-Acre Park.docx 18 HWA GeoSciences Inc.