ARCHIVED REPORTS XR0000869 - Laserfiche WebLink

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tThe culmination ofpast ground water monitoring events indicate that there is a plume of BTEX and • TPHg at a depth of 45' and approximately 20' tluck The BTEX and TPHg plume contains about 0 005Kg of Benzene and about 0 32Kg of TPHg. Please note that in the original Site Conceptual Model there was a nustake in converting µg to Kilograms resulting in the reported values being 1,000 tunes too lugh. There is a second plume which contains 1,2-DCA. The 1,2-DCA plume is at a depth of 70' and approximately 25'thick The 1,2-DCA plume contains about 0.028Kg of 1,2-DCA. Please note again,that in the original Site Conceptual Model there was a mistake in convertingµg to Kilograms ' resulting in the reported values being 1,000 tunes too high. Attached is a plan view showing the Knits of the two plumes, Exhibit A The plumes are contaminants that have dissolved into the water The plumes are not free product moving between the soil particles RECEPTOR SURVEY The receptor survey is attached,Exhibit F The Receptor Survey indicates that there are no drinking ' water wells within 2,000'of Vogue Cleaners,but there are three irrigation wells within the 2,000' They are as follows Owner Pump Use ' 1 St Joseph's Hospital 20HP Irrigation Only 2 San Joaquin County Catholic Cemetery 15HP Irrigation Only 3 Stockton Rural Cemetery 50HP Irrigation Only I4 Vogue Cleaners 1/4HP Non-Functional (Destroyed 6/10/05) There is a municipal drinking water well that is 2,500'up gradient from Vogue Cleaners,and is not threatened by this site Since the time the original Site Conceptual Model had been written the non- functional domestic well within the Vogue Cleaners building has been destroyed NATURAL ATTENUATION The trend lines on the attached graphs show that natural attenuation is taking place for various monitoring wells,Exhibit C The Benzene m MW-3S is decreasing at about 2 50/o/year The TPHg in MW-3S is decreasing at about 4 50/o/year Z r 1,2-DCA is to MW-3S, MW-2S&D, MW-3S&D, MW-5S&D The wells that show a decreasing trend line are MW-1_S(-7 5%/yr),MW-2S(-16 80/o/yr),MW-2D(-7 90/o/yr),MW-3S(-5 20/o/yr),and MW-5D(-7 5%/yr) The wells that show an increasing trend line are MW-3D(+1 8%/yr),and MW- 5S(+4 40/o/yr) RISK ASSESSMENT The contaminants of concern at the Vogue Cleaners site Benzene and TPHg in soil and groundwater,and 1,2-DCA in groundwater Human consumption of Benzene,TPHg,or 1,2-DCA from the Vogue Cleaners site is highly unlikely The pathways of human consumption are 1) inhalation of vapors from the soil 2) inhalation and skin exposure of dust indoors and outdoors 3) direct ingestion of soil particles 4