ARCHIVED REPORTS_XR0006331 - Laserfiche WebLink

Home Browse Search

1.0 INTRODUCTION Upgradient Environmental Consultants was retained by Mrs Mahone Conrady in A4arch, 1998 to provide site remediation and groundwater monitoring services at her property located at 1002 Yosemite Street in Stockton, California The property is the former location of a gasoline service station that was demolished about 1980, when the underground fuel storage tanks were removed Upgradient submitted a Corrective Action Plan in April, 1998, which was approved by Michael Infurna of the Environmental Health Division c t San Joaquin County Public Health Services (PHS/EHD) in crud-Apnl, and the corrective action was performed in late April The purpose of this report is to present the results of monitoring activities in November and December The investigation is currently managed for Mrs Conrady by Mr James Dyke ofNeumiller& Beardslee, Attorneys at Law 2.0 BACKGROUND The property is located on the northeast corner of Acacia and Yosemite streets in a predominantly residential area of west Stockton (Figure 1) The site is now vacant, bu was operated as a gasoline service station from 1961 to 1978 The fuel storage tanks and dispenser islands were removed in 1980, and observers noted evidence of an unauthorized release of gasoline Investigation of the extent of contamination began in 1990, and was completed in 1997 Site remediation was begun in April 1998, when seven bonngs were dnlled and a sliary of Oxygen Releasing Compound (ORC) was injected into each boring to provide oxygm to enhance natural bioremediation of the hydrocarbons Since that time, groundwater has been morutored on a regular basis to track changes in dissolved oxygen and hydrocarbon concentrations. 3.0 MONITORING PROCEDURES AND RESULTS 3.1 Depth to Groundwater The depth to groundwater in each well was measured on November 7 and December 7, and the depths were recorded on the Well Monitor Report(Appendix A) Depths were mea,ured with a Solinst water level sounder to an accuracy of 0 01 foot Water level and casing elevation data are tabulated in Table 1 and were used in constricting a groundwater gradient map for both days (Figures 2 and 3) The maps are similar in appearance to those for previous monitoring events, and all of the reaps indicate that the water table has a natural slope to the northeast and a trough along the west (street) side of the site This trough appears to have enlarged over time, and now extends onto the Coarady property as far as SW-1 The significance of this is uncertain, but now that the trougf is no longer restricted to the area beneath Yosemite Street, it is somewhat difficult to attribu,.e the 2