SR0084326 - Laserfiche WebLink

Home Browse Search

Sampling and Analysis Plan for Phase II Environmental Site Assessment South Pointe Property: 701, 705, 833, 855 West Weber Avenue Stockton, California Background May 17, 2021 2.3 PREVIOUS INVESTIGATIONS/REGULATORY INVOLVEMENT 2.3.1 Geotechnical Assessment - 2006 In September and October 2006, Neil O. Anderson and Associates performed a geotechnical investigation of the site which consisted of advancing 14 exploratory soil borings to depths ranging from 16.5 to 41.5 feet below ground surface (ft bgs). Encountered materials consisted of loose to well- compacted sandy clay, sandy gravel, and clayey sand mixed with gravel, concrete, and brick debris to depths ranging from 3 to 16 ft bgs. The investigation identified the widespread presence of concrete debris beneath the site, including buried foundations and underground structures, and recommended these materials be removed during site redevelopment and resulting voids filled with appropriate fill. Additionally, onsite native soils were deemed appropriate for use as engineered fill, but that this fill should be free of vegetation and deleterious material. 2.3.2 Environmental Assessment - 2007 Wallace-Kuhl &Associates, Inc. (WKA) performed a site-wide investigation and published the results in the document entitled Subsurface Investigation Report, Stockton Promenade & Southpointe Properties, Stockton, California dated March 25, 2008 (WKA, 2008). The investigation was performed on behalf of the City of Stockton Redevelopment Department on a self-directed basis (i.e., not subject to formal regulatory oversight). Investigation activities performed by WKA between February and November 2007 were intended to characterize site soils and shallow groundwater for potential chemical impacts related to historical industrial uses. The majority of the work was performed on the South Pointe property (subject site of the current investigation) but also included the Promenade area, which was subsequently redeveloped as the pedestrian arcade which currently exists between the site and Stockton Channel to the north and Mormon Slough to the west. During three phases of investigation WKA advanced 60 test pits on the South Pointe site to a maximum depth of approximately 17 ft bgs. Investigative activities were focused along the central rail lines historically transecting the site east to west, and in the northeast corner of the site, where a significant area of petroleum hydrocarbon-impacted soil was identified. Multiple rounds of investigation allowed WKA to analyze initial samples and conduct follow-up, `step out' sampling to characterize areas with elevated constituents of concern. Test pit locations are illustrated on the WKA Figure 4 included in Appendix A. Encountered materials consisted of artificial fill and building rubble to depths of approximately 2 to 8 ft bgs in the locations of former onsite structures. Deeper native soils consisted primarily of fine-grained sand to depths of 10 to 15 ft bgs. Railroad track remnants (ties and ballast)were observed at the location of test pit TP-9, located in the western portion of the site. MProject No.: 185704833.5.3&5.4 2.2