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RI NIRI-Adaional `uJ and(,a.nni,.m. I,n.,nXmi.m I l:rni.�A II.1. ,til:u m.i \u.Ati1-A over the channel and slough. The grotmdwaler gradient, discussed in Section 1.3 of this report, was estimated using the survey information and the depth to x\ater measurement in the v.,ells and to the channel and slough water surface. I 3.6 Groundwater Sampling (irounckNater samples were collected at least �3 hours follc»�ing development of the monitor \�clls. Prior to sample collection, the static \tater leycl in each \yell %vas measured to the nearest 0.01- foot \lith a batten-operated, water-level meter. A disposable bailer was lowered into each Nell to check for floating product, petroleum odors and/or sheen. ' The monitor wells were purged using a clean bailer until the temperature, electrical conductivity and pH of the water stabilized. At least three casing volumes of water were purged from each monitor \\ell. The purged water from each well was containerized in a 55-gallon drum and left on site pending analytical results. Groundwater monitoring and measurement field forms are included ` in Appendi\ C. ' Lach well was alloyed to recover to at least RO`io of its pre-purge water level before sampling. The groundwater samples were collected with clean, disposable bailers. Each Nvater sample was gently ' drained from the bailer to three (3) 40-m1 Glass, volatile organic analyses (VOA) vials, and hyo (2) amber glass liters, using a bottom-emptying: device. Each vial and bottle was labeled for sample ' identification and placed in a cooler chilled with ice. Upon completion of the fieldwork, the water samples were delivered tinder chain-of-custody procedures to GeoAnalylical Laboratories, Inc., in ' Modesto, California. 1 3.7 Laboratory Analysis The soil and groundwater samples collected from the monitor wells were analyzed for BTEX ' and gasoline add itivesloxygenates by EPA Method 8260, TPH-G by Method 5030/LUFT, and TEPH by EPA Method 3550/LUFT (EPA Method 3510/LOFT for %later). The gasoline oxygenates/additives ' include methyl tcrtiary-hutyl ether (MTBE), ethanol, tertiary-butanol. di-isopropyl ether (DIPS), ethyl tertiary-butyl ether (ETBE). and tertiary-amyl methyl ether (TAME). The analytical methods and analytical detection limits arc presented in Table 3.1, on the next page. ' {�J CONDOR