Laserfiche WebLink
- <br /> . <br /> . W <br /> EXECUTIVE SUMMARY <br /> This report contains data gathered during the subsurface <br /> petroleum hydrocarbon investigation at 229 Moffat Boulevard, <br /> p <br /> Manteca, California. The source Of the hydrocarbons was a 700- <br /> - <br /> gallon underground storage tank containing leaded gasoline that was <br /> wells were subse- <br /> removed in November 1986thethetextent ofohyd9ocarbons in soil and <br /> quently installed to def or survey, chemical <br /> groundwater. other work included a soil-vapor <br /> slug tests. <br /> analyses, groundwater level measurements, <br /> Hydrocarbon concentrations in soil beneath the tank pit were <br /> as high as 1,400 parts per million; none were detected in samples <br /> in several <br /> from borings placed approximately 100 to 120 feat away <br /> directions. Soil-vapor survey results confirm that the extent of <br /> the affected soil has been defined. A very gentle groundwater <br /> gradient (less than 0.001 ft/ft) to the north suggests that little <br /> plume migration has taken place. <br /> On November 14 and 15, 1989, <br /> of total petroleum hydrocarbons as gas- <br /> dissolved concentrations <br /> 000 parts per billion in groundwater <br /> oline were as high as 110, plume is <br /> sampled close to the tank pit. The lateral extent of the <br /> i to the northeast, where aj <br /> well defined in all directions except Because the hydro- , � <br /> blocked well temporarily prevented sampling. q <br /> and the nearest municipal <br /> carbons are confined to the subsurface' <br /> water-supply wells are located well beyond the extent of the <br /> anent. <br /> dissolved plume, no public health risk is app <br /> ermeabilityslow groundwater flow, and <br /> Because of high soil p , a combination of vapor <br /> the presence of the building at the site, <br /> extraction and groundwater extraction and treatment reviewed recommended <br /> extra ort is beina_ _ <br /> to remediate this site. While this report ., ----��_ <br /> the Final Remedial Plan cos will <br /> mpiled /interim remedial the obstructed <br /> performed. These include: salvaging and sampling <br /> quarterly ground- <br /> _._. _ a <br /> well, <br /> monthly groundwater elevatian...measurem ` <br /> water sampling and analyses, soil-vapor extraction tests and <br /> ,yr em --- <br /> well. <br /> design, and the installation of a recovery.- __ . <br /> GROtMWATER <br /> -- TECHNOLOGY.INC. <br />