3301 SEAWAY BLVD Geotech Report 2022-10-25

January 13,2016 Project No.T-7342 5.0 DISCUSSION AND RECOMMENDATIONS 5.1 General Based on our study, there are no geotechnical conditions that would preclude the development of the site as currently planned. The industrial buildings can be supported on conventional spread footings bearing on competent native soils underlying the 6 to 18 inches of organic surficial soils, or on structural fill placed on a subgrade of competent native soils. Floor slabs and pavements can be similarly supported. The native glacial till and the siltier outwash soils observed at the site contain a significant amount of fines and will be difficult to compact as structural fill when too wet or too dry. The ability to use these native soils from site excavations as structural fill will depend on its moisture content and the prevailing weather conditions at the time of construction. If grading activities will take place during the wet winter months, the owner should be prepared to import clean granular material for use as structural fill and backfill. The cleaner outwash soils should be suitable for use as structural fill year round. The following sections provide detailed recommendations regarding the above issues and other geotechnical design considerations. These recommendations should be incorporated into the final design drawings and construction specifications. 5.2 Site Preparation and Grading To prepare the site for construction, all vegetation, organic surface soils, and other deleterious materials should be stripped and removed from the site. Based on conditions observed in our test pits, we expect that surface stripping depths between six and 18 inches will be required to remove organic surficial soils. These organic surficial soils will not be suitable for use as structural fill, but may be used for limited depths in nonstructural areas or for landscaping purposes. Once clearing and stripping operations are complete, cut and fill operations can be initiated to establish desired grades. Prior to placing fill, all exposed bearing surfaces should be observed by a representative of Terra Associates to verify soil conditions are as expected and suitable for support of new fill. Our representative may request a proofroll using heavy rubber-tired equipment to determine if any isolated soft and yielding areas are present. If excessively yielding areas are observed, and they cannot be stabilized in place by compaction, the affected soils should be excavated and removed to firm bearing and grade restored with new structural fill. Beneath embankment fills or roadway subgrade if the depth of excavation to remove unstable soils is excessive, the use of geotextile fabrics, such as Mirafi 500X, or an equivalent fabric, can be used in conjunction with clean granular structural fill. Our experience has shown that, in general, a minimum of 18 inches of a clean, granular structural fill placed and compacted over the geotextile fabric should establish a stable bearing surface. Page No. 8