Laserfiche WebLink
Chevron Products Company Page 5 <br /> Chevron Service Station 9-4275,2905 Benjamin Holt Dnve,Stockton,California May 20,2002 <br /> ® Porosity of the various soil types beneath the site range from 26-53% for sand to 34-64% <br /> for clay A conservative 35% site-wide porosity was assumed to estimate the available <br /> water in saturated soils <br /> Mass Flux/Mass Discharge <br /> Attachment G provides a mass flux/mass discharge (Md) calculation These data and calculations <br /> suggest <br /> • Mass flux is approximately 3 2 x 10-2 grams per day (g/day), <br /> • Municipal Well No 10 located approximately 50 feet to the east of the site, has a <br /> potential yield of approximately 985 gallons per minute (gpm), <br /> • A predicted mass discharge of MtBE in Municipal Well No 10 is 2 5 x 10-2 (0 025 µg/L), <br /> which is essentially non-detectable using current laboratory techniques, <br /> • The California Environmental Protection Agency (Cal/EPA) preliminary remediation <br /> goals (PRG) for MtBE in tap water are 6 2 µg11, which would require a mass flux of <br /> approximately 7 6 x 10-2 g/day <br /> Mass Flux calculation is presented in Attachment G <br /> Chemical Concentrations vs. Time <br /> Attachment H provides plots of chemical concentrations vs time Concentrations of <br /> TPHg and benzene are shown to decrease over time in both on-site and off-site wells <br /> Concentrations of MtBE were found to decrease in off-site wells, however on-site wells <br /> appear to exhibit an increasing trend in MtBE concentrations <br /> Chemical Concentrations vs. Distance <br /> Attachment I provides chemical concentrations vs distance plots Concentrations of <br /> MtBE in most wells are shown to decrease as the distance from the source area <br /> increases <br /> Site Conceptual Model <br /> A site conceptual model (SCM) has been omitted from this site assessment report <br /> Further data compilation and analysis is needed to adequately develop a SCM <br /> Additional Work performed <br /> During the term of this site assessment, Chevron and Arco Products Company filed an <br /> application with the State Water Resources Control Board for commingled plume status <br /> under the State UST fund Future assessment and remediation efforts at this site will be <br /> designed in conjunction with state UST fund approval <br /> I 1Chevron1942751REPORTS12001 CPT SA and Muni sampling Rev A doc <br />