Laserfiche WebLink
TREADWELL & ROLLO <br /> feet, respectively. The soil samples were collected using a 2-inch I.D. modified <br /> California split-spoon sampler lined with 6-inch-long brass tubes. The sampler and tubes <br /> were cleaned with a trisodium phosphate solution and rinsed with tap water prior to <br /> sampling. The soil samples were retained in the tubes, which were sealed with <br /> aluminum foil and plastic caps to minimize the loss of any potentially volatile <br /> compounds. The tubes were stored in a cooler with ice until delivery to a state-certified <br /> analytical laboratory using chain-of-custody procedures. <br /> The soil encountered in the borings is described on the boring logs (Figures 3a through <br /> 3g) in accordance with the Unified Soil Classification System presented in Figure 4. The <br /> distribution of geologic units within the study area is shown on Figure 5. These are <br /> generalized soil profiles based on the interpretation of and interpolation between the <br /> borings. <br /> 4.2 Monitor Well Installation <br /> The three borings were converted to groundwater monitor wells using similar <br /> construction methods. A 15-foot length of 0.020-inch slotted schedule 40 polyvinyl <br /> chloride (PVC) threaded casing and approximately 21 feet of blank casing was installed <br /> in each of the wells. Lonestar No. 3 sand was placed in the annular space from the <br /> bottom of the slotted casing to approximately 2 feet above the top of the slotted casing. <br /> A surge block was used to induce settlement of the sand pack prior to the placement of <br /> a 2-foot-thick bentonite pellet seal which was hydrated with tap water. A cement and <br /> bentonite grout seal was constructed above the bentonite pellets by pumping through a <br /> tremie pipe. A steel casing with a locking cover was installed above the PVC well casing <br /> to protect its integrity. The well construction details are illustrated on the boring logs. <br /> The drilling and well construction were performed under the intermittent supervision of/ <br /> representatives of the San Joaquin County Public Health Services Department. <br /> �r <br /> 4 <br /> 1107A201.CRJ 5 November 1991 <br />