Laserfiche WebLink
1 <br /> November 1, 1991 <br /> 17060, 025 . 03 Harding Lawson Associates <br /> Mr, Hai Miller <br /> The Southland Corporation <br /> Page 2 <br /> GROUNDWATER SAMPLING <br /> ' On September 12 , 1991, HLA collected groundwater samples from <br /> all 14 monitoring wells. Before sampling, we purged at least <br /> three casing volumes from each well while monitoring <br /> temperature, pH, and conductivity. After those parameters <br /> stabilized, groundwater samples were collected with a clean <br /> stainless steel bailer, and decanted directly into <br /> ' laboratory-prepared volatile organic analysis (VOA) vials and <br /> sterilized fecal coliform sample containers. The samples <br /> were labeled and placed into an ice-chilled cooler for <br /> ' transportation, under chain-of-custody, to a state-certified <br /> chemical testing laboratory. Between wells, all purging and <br /> sampling equipment was cleaned with an Alconox solution and <br /> rinsed with deionized water. <br /> CHEMICAL TESTING <br /> 1 Samples were sent to Superior Analytical Laboratories an <br /> Martinez, California, and analyzed for total petroleum <br /> hydrocarbons (TPH) as gasoline, using EPA Test Method 8015; <br /> and for benzene, toluene, ethylbenzene, and xylenes (BTEX) , <br /> using EPA Test Method 8020. Samples for fecal coliform were <br /> submitted to BC Analytical in Emeryville, California. The <br /> results of chemical analyses are presented in Table 1, along <br /> with groundwater data from preceding phases of site <br /> investigation and characterization. Laboratory data sheets <br /> ' and chain of custody are included in the Appendix. <br /> GROUNDWATER GRADIENT <br /> Water level measurements were obtained using a chalked steel <br /> ' tape accurate to 0. 01 feet. Well survey and water level data <br /> are presented in Table 2 . The water levels in each of the <br /> wells have declined relative to previous periodic <br /> measurements. Our calculations indicate a northeasterly <br /> ' hydraulic gradient, which is consistent with previous data <br /> for the site. <br /> ' RESULTS AND DISCUSSION <br /> ' The pH of purged groundwater monitored in the field was <br /> consistently between 6. 01 and 7. 52 . Conductivity <br /> measurements ranged from 630 to 2 , 200 uS/cm. Results of <br /> l� groundwater analyses indicate decreasing concentrations of <br />