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Phase ii Environmental Site Assessment Multi-Modal Station Stockton,San Joaquin County,California Page 3 bearing units of the local natural gas fields The Cretaceous deposits are underlain by basement rock belonging to the Franciscan Assemblage or the Sierra Nevada Granitics and Metamorphics Previous work performed by Condor in the vicinity of the site and subsequently confirmed by drilling at the site indicates that the soils of downtown Stockton are predominantly clays, sandy clays, and silty clays, especially near the surface Groundwater monitoring activities at nearby properties indicate the general groundwater gradient in the vicinity of the site is to the east, with the gradient at individual sites ranging from the northeast to the southeast The site may receive groundwater flow from properties to the northwest, west, and southwest Addresses that appeared during the government database search are tabulated in the Phase I ESA report with their approximate distance from the site and their gradient position with respect to the site The site does not appear to receive significant runoff from other properties Drainage from the site and adjacent properties appears to flow to the adjacent streets where it is conveyed to the city storm drainage system 4.0 FIELD PROCEDURES 4.1 SITE PREPARATION On April 17, 2002, Condor submitted an application for encroachment on public right-of-way to the City of Stockton Public Works Department for the borings to be advanced within the roadway of the site On April 18, 2002, Condor submitted eight well permit application forms to the San Joaquin County Environmental Health Department (EHD) One well permit application form was submitted for each of the six blocks and two well permit application forms were submitted for the borings to be advanced within the roadways--one for cone penetration test(CPT) drilling and the other for Geoprobe drilling On May 10, 2002, Condor mailed letters to the owners of the properties located within the six-block area notifying them of the upcoming work intended to be conducted at the site All CPT and direct push boring location areas were marked with white paint, and Underground Services Alert (USA) was notified at least 72 hours in advance of the drilling fieldwork to locate and identify underground utilities in the vicinity of the work area However, because many of the proposed boring locations were on private property, some utilities contacted by USA did not mark the locations of their utilities past property boundaries and onto private properties EHD and the City of Stockton were notified of the fieldwork schedule at least 48 hours in advance Prior to commencement of fieldwork each day, a tailgate safety meeting was conducted and a site-specific Health and Safety Plan was discussed with, and presented to, all field personnel for their signatures 4 2 INVESTIGATIVE PROCEDURES 4.2.1 Investigative Rationale The Phase 11 ESA was designed to evaluate potentially large and medium-sized soil and groundwater contamination in areas of concern,both on and off site, previously identified in the Phase I ESA by RECs and HRECs The Phase II ESA was conducted in order of the following investigative methods A CPT investigation involved the installation of CPT borings around the site in the public right- of-way to obtain information regarding the soil types present beneath the site, especially aquifers (soil types that allow groundwater to flow) and aquitards (soil types that limit the ability of groundwater to flow) This was done to determine at what depths groundwater might be expected beneath the site ➢ A limited ground penetrating radar (GPR) investigation was designed to obtain additional . information pertaining to the subsurface conditions at the proposed boring locations on selected �c CONDOR