Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
ItA <br /> • A S S O C I A T E 5 I N C <br /> current AST location contained elevated concentrations of total petroleum hydrocarbons as <br /> gasoline (TPHg), total petroleum hydrocarbons as diesel (TPHd), and methyl tertiary butyl ether <br /> (MTBE) The extent of impacted soil was defined and generally extended along the backside of <br /> the levee, west of the store The Ariel extent was approximately 200 feet in length and 65 feet in <br /> width and was limited to depths between 5 and 15 feet bgs Additionally, MTBE impacted soil <br /> extended eastward, between the store and office building <br /> The groundwater plume generally extended along the backside of the levee, west of the store, and <br /> was approximately 225 feet long and 70 feet wide Concentrations were highest in the boring <br /> adjacent to the former and current product lines The extent of TPHg in groundwater was not <br /> fully defined to the west and south but samples indicated that the borings in those directions were <br /> near the edge of the plume Additionally, TPHd and MTBE have migrated eastward <br /> GROUNDWATER MONITORING AND SAMPLING <br /> On September 30, 2003, ATC personnel conducted the third quarterly groundwater monitoring and <br /> sampling of monitoring wells MW 1 through MW7 Water level measurements were collected from the <br /> monitoring wells prior to purging and sampling Well locations are shown on Figure 2 <br /> • Subsequent to monitoring, each well was purged by extracting a minimum of three well casing volumes <br /> of groundwater While purging, groundwater parameters (temperature, conductivity, and pH) were <br /> monitored and allowed to stabilize before water samples were collected Samples were collected using <br /> dedicated, disposable bailers with bottom emptying devices to reduce volatilization All purged <br /> groundwater was contained in 55-gallon drums approved for hazardous liquid storage on-site pending <br /> appropriate disposal Groundwater well purge and sample logs are contained in Attachment 1 <br /> The groundwater samples collected from each well were placed on ice and transported under <br /> chain-of-custody documentation to Argon Laboratories (ELAP #2359) in Ceres, California The <br /> groundwater samples were analyzed for TPHd, TPHg, benzene, toluene, ethylbenzene, and xylenes <br /> (BTEX) utilizing EPA methods 8015/8021B and total lead utilizing EPA method 200 9 Fuel <br /> oxygenate additives including MTBE were analyzed by EPA method 8260B <br /> RESULTS <br /> Water levels have increased an average of 0 98 feet since the last monitoring event on June 5, 2003 <br /> (Table 1) Depth to groundwater levels ranged from 3 18 to 10 75 feet below ground surface(bgs) A <br /> groundwater gradient map was created using the data collected on September 30, 2003 (Figure 3) <br /> Groundwater generally flows to the east, away from the slough, with a gradient of approximately 0 07 <br /> feet/foot or 370 feet per mile <br /> TPHd was not detected in groundwater samples collected from wells MW 1 through MW7 TPHg was <br /> not detected in any of the groundwater samples collected from wells MW 1 through MW7 BTEX <br /> were not detected in the groundwater samples collected from wells MW1 through MW7 The samples <br /> s 1environmental1625141quaAly\3gr-2003 doc 3 <br />