COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

CONDOR February 22, 2019 Ms. Vera Fischer Engineering Geologist California Regional Water Quality Board, Central Valley Region 11020 Sun Center Drive #200 Rancho Cordova, CA 95670 CONDOR EARTH 188 Frank West Circle, Suite I Stockton, CA 95206 209.234.0518 Fax 209.234.0538 www.condorearth.com Subject: Addendum to Subsurface Investigation Work Plan dated June 21, 2018 SJC Records Retention Center, 630 N. California Street, Stockton, CA 95202 Condor Project No. 5960135 Dear Ms. Fischer Condor Earth (Condor) has prepared this Addendum to the Subsurface Investigation Work Plan (Work Plan) dated June 21, 2018, to address modifications to the scope of work associated with subsurface investigation activities proposed for the San Joaquin County Records Retention Center (Site) located at 630 N. California Street, Stockton, California (Figures 1 and 2, attached). This Addendum was prepared at the request San Joaquin County General Services (the Client) via email, as a follow-up to a project meeting that took place in November 2018, in which additional investigation was discussed, to sample shallow groundwater downgradient (north-northeast) of the closed in place underground storage tank (UST) at the Site. The location of the proposed groundwater sample is in the southern portion of the parking lot of J. E. Cooley Jr. Funeral Service, located at 640 N. California Street, Stockton, California. The Work Plan outlines proposed methodology to collect shallow soil samples from two locations near the closed -in-place UST at depths of approximately 4.5-5.0 feet below ground surface (bgs) using a hand auger in order to evaluate the Site for closure pursuant to the State Water Resources Control Board's Low -Threat Underground Storage Tank Closure Policy (LTCP). A Condor field technician attempted to collect the shallow soil samples near the UST on December 17, 2018.The borings could not be advanced by hand auger, however, due to refusal of the auger within the upper 2 feet of the ground surface. This Work Plan Addendum describes the methodology to employ a drilling company equipped with a direct push drilling rig to advance the shallow borings (HA2 and HA3) and to collect the downgradient groundwater sample (GW 1). The locations of the proposed borings on present on Figure 2 in Appendix A. Condor proposes to collect the shallow soil samples on site and the off-site groundwater sample using a direct push drilling rig. Cascade Environmental (C-57 #938110) will conduct the drilling. Drilling locations will be marked in white paint and cleared by USA and a private utility locator. The off-site boring will be advanced to a depth of approximately 25 to 30 feet bgs. Continuous core soil samples will be collected from the boring with a 2 -inch outside diameter (OD), 4 -foot -long core barrel fitted with a clean, single use, polyethylene liner. Soil core samples will be characterized pursuant to the Unified Soil Classification System (USCS) and, depending upon field evidence of contamination, selected soil samples will be transported under chain -of -custody procedures to BC Laboratories, Inc. (ELAP Certification No. 1186).