ARCHIVED REPORTS_XR0004001 - Laserfiche WebLink

Home Browse Search

J y, • • Geofogical Technics Inc. 2741 River RAvd Mar(esto,CdYfornia 95351 (209)538-6424/Fax#538-5852 ' REPORT Sinclair Trucking 3780 West Linne Road Tracy, California Project No, 320.2 November 8, 1999 EXECUTIVE SUMMARY ' This report summarizes the 3rd Quarter 1999 groundwater monitoring and testing that took place on September 22, 1999. During this monitoring event, four monitoring wells and one domestic well were sampled and tested. A summary of findings include: 1. Hydrogeology • Groundwater gradient and bearing were calculated and found to be 0.0041 Rift at N25°E. • Note: It should be noted that the wells used for calculating the groundwater gradient ' have been change to MW-2, 3 & 4. The reason for this is that the well top measuring point elevation survey performed on September 22, 1999 showed a modified spatial relationship between MW-2 & 3 (see surveyors report in Appendix D). ' • For the three years, the shallow groundwater gradient has moved towards the NE. 2. Groundwater Contamination • Floating product has not been detected. • Low concentrations of aromatic hydrocarbon compounds (BTEX) are present in MW- 1 while only trace concentrations were found in MW-4. • The concentrations of TPH-G in MW-4 has dropped significantly since the first monitoring event, suggesting that the contamination plume may be smaller then ' originally thought from the February 1999 monitoring event results. • Total petroleum hydrocarbons as gasoline(TPH-G)are present only in MW-1. • None of the oxygenated fuel compounds (OFCs) were detected in any of the wells. • MW-2 & 3 water samples did not contain any of the petroleum hydrocarbon compounds tested for. • The domestic water well sample did not contain any of the chemicals tested for. The following conclusions are drawn from the data generated to date on this project: 1. Both the soil and groundwater environments in the vicinity of the former UST are impacted by gasoline. ' 2. Elevated concentrations of contamination extend downgradient in the sand unit between 12 to 16 feet below ground surface. 3. MW-2 & 3 and the domestic well continue to be free of contamination.