Laserfiche WebLink
Californi&egional Water Quality Conol Board <br /> Central Valley Region <br /> ]Catherine Hart,Chair Arnold <br /> Linda S.Adams 11030 Sun center Drive H200,Rancho COMM,Caliramia 95670.6114 Schmmenegg, <br /> Secmaryfar Phone(916)464-3391 •FAX(916)464A645 Gmvrnor <br /> airomnenml Projection htipl/w.tvW,waterboards.ea.gov/mnirnlvallcy <br /> 7 September 2010 <br /> Mr. Mike Bauer <br /> Chevron Environmental Management Company <br /> 145 S. State College Boulevard <br /> P.O. Box 2292 <br /> Brea, CA 92822 <br /> SECOND QUARTER 2010 GROUNDWATER MONITORING REPORT, CHEVRON <br /> BULK FUEL TERMINAL #1001621, 22888 KASSON ROAD, BANTA, SAN JOAQUIN <br /> COUNTY <br /> Regional Water Quality Control Board, Central Valley Region (Central Valley Water <br /> Board) staff reviewed the 30 July 2010 Second Quarter2016 Groundwater Morptoflrig <br /> Report(Second QMR) submitted by ARCADIS on behalf of Chevron Environmental <br /> Management Company (Chevron)for the bulk fuel terminal located at 22888 Kasson <br /> Road in Banta (Site). <br /> Three groundwater bearing zones have been identified beneath the Site. They include <br /> the Upper A.(UA) zone between depths of five and 15 feet.below ground surface (bgs), <br /> the A-zone from 15 to 35 feet bgs, and the B-zone which starts at 50 feet bgs.. <br /> Groundwater monitoring for the second quarter was conducted during May 2010. Depth <br /> to groundwater in the three zones ranged from about four to 12 feet bgs and flowed <br /> north-northeast between 0.001 and 0.003 feet per foot.Vertical gradients were <br /> predominantly upward between the UA- and A-zones and between the A-and B-zones. <br /> These observations are fairly consistent with historical trends. Total petroleum <br /> hydrocarbons as diesel (TPHd) is the main contaminant of concern at the Site, and the <br /> highest concentrations generally occur in the loading Tack and former underground <br /> storage tank (UST) area. The petroleum hydrocarbon plume extends off-site to the <br /> northeast. Accordingly, Chevron has subdivided the plume into off-site and on-site <br /> portions. <br /> Separate phase hydrocarbon-(SPH) was observed in two wells during second quarter, <br /> MW-37UA and MW-40UA. The maximum detection of TPHd was observed in MW-26A <br /> in the former loading rack area at 4,800 micrograms per liter (pg/L). TPHd was also <br /> -•present in B-zone wells in the off-site plume at concentrations rangi/ng�frg57 NgIL in <br /> MW-756 to 290 pg/L in MW-72B. TPH as gasoline(TPHg), benzene, toluene, <br /> ethylbenzene, and total xylenes (BTEX) and tertiary butyl alcohol (TBA) were non- <br /> detect (ND) in the off-site wells in all three zones. There were minor detections of <br /> methyl-tertians-butyl-ether(MTBE)..The concentration of TPHd in upgradient well <br /> MW-6A decreased from 360 pg/L during the third quarter of 2009 to 64 pg/L during the <br /> first quarter of 2010 but was not monitored during the second quarter. <br /> California Environmental Protection Agency <br /> Req-tied Paper <br />