3535 RIVERFRONT BLVD Geotech Report 2023-02-22

September 24, 2018 HWA Project No. 2015-061-21 primary and secondary consolidation. All utility connections to the Lift Station 33 wet/dry well and deep manhole structures should be designed with flexible connections to accommodate differential settlements. 4.4.2 Anticipated Differential Settlements Associated with the CSO Outfall Pipe An existing 60-inch concrete CSO pipe crosses below the proposed grade increase at the south end of the site. The foundation of this pipe is currently unknown. However, we expect that at the very least, the CSO outfall construction would have removed some of the compressible soils under the pipe. Therefore, it is likely that the CSO alignment will represent a line of reduced settlement once the grade is increased. This linear zone of reduced settlement will result in a high point of any proposed utilities crossing over the CSO outfall pipe. We recommend that all pipes crossing the CSO outfall alignment be designed with flexible pipe material and enough fall to maintain functionality assuming as much as 10 inches of differential settlement across the outfall alignment. 4.5 FOUNDATION RECOMMENDATIONS 4.5.1 Restroom Foundation It is our understanding that the proposed restroom structure is to consist of a single-story building located wholly within preload surcharge Zone 1. Based on our evaluations we expect that preload surcharge Zone 1 could experience 3 to 5 inches of settlement over 50 years with 2 inches of differential settlement expected. To accommodate these anticipated differential settlements, we recommend that the restroom structure be founded on a structural mat foundation capable of tolerating these settlements. An allowable bearing pressure of 2,000 psf should be assumed for the mat foundation. The mat foundation should be founded on a minimum 1.5-foot- ' thick layer of compacted Crushed Surfacing Base Course. The Crushed Surfacing Base Course should extend a minimum of 5 feet laterally from the outside edge of the mat foundation in every direction. 4.5.2 Foundation Consideration for the Picnic Shelter Canopy Roof Structure It is our understanding that a picnic shelter is to be constructed to the east of the restroom facility. The picnic shelter is to consist of a steel cantilever canopy roof structure that is to be constructed as part of the future phases of park improvements. The picnic shelter canopy roof structure will be highly susceptible to damage due to differential settlements across the structure. Due to the anticipated long-term settlement expected across the location of the picnic shelter, we recommend that the structure be either supported on small diameter steel piles (Pin Piles) or a mat foundations with the ability to relevel the individual structural elements. Final Geotechnical Report-3-Acre Park.docx 16 HWA GeoSciences Inc.