WORK PLANS - Laserfiche WebLink

Home Browse Search

INTRODUCTION GHH Engineering, Inc. (GW is currently providing West Lane Fuel (West Lane) professional engineering services to assist them with environmental issues pertaining to their site located at 3300 N. West Lane, Stockton, California, as shown on Figure 1. Mr. Jay McIlrath has authorized GHH to prepare this Additional Assessment Workplan (AAWP) for the site. This workplan has been prepared for submittal to the San Joaquin County Environmental Health Department(County),the lead regulatory agency overseeing environmental issues at the site. BACKGROUND AND SITE HISTORY Site Description The site is currently a retail convenience store located on the northwest corner of West Lane and Alpine Avenue, 3302 West Lane, Stockton, CA. The property is asphalt paved and houses one rectangular-shaped office/store building and two former dispenser island locations as shown on Figure 2. The site formerly contained three underground storage tanks (UST). Location maps for the UST's were unavailable. Geology and Hydrogeology Geologically, the property is underlain by the Quaternary Modesto Formation and the deeper Quaternary Riverbank formation,both of which consist mainly of arkosic alluvium derived mainly from erosion of the Sierra Nevada Mountains to the east. Both the Modesto and Riverbank formations are part of the Great Valley sedimentary sequence of rocks which fill the large Great Valley sedimentary basin which was originally derived as a forearc basin between the Sierran arc to the east and the subduction zone to the west. Stockton is located within the San Joaquin Valley which consists of the southern two thirds of the Great Valley province. The northwesterly flowing San Joaquin River and its tributaries are the main drainage feature of the San Joaquin Valley. Groundwater is present at the site at approximately 50 feet below ground surface (bgs). Site History In 1997,three gasoline dispensing UST's were removed. Soil samples collected up to 24 feet bgs at the base of the former UST's excavation reported high concentrations of total petroleum hydrocarbons, as gasoline(TPH G),TPH,as diesel (TPH D),benzene,toluene, ethylbenzene,total xylenes,(BTEX)and fuel oxygenates. One soil sample was reported to contain methyl tertiary butyl ether (MTBE) at a concentration of 0.650 mg/kg. Based on the soil data, the Central Valley Regional Water Quality Control Board(Regional Board)required drilling of a single soil boring and the collection of soil and groundwater samples for laboratory analyses.