Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
t <br /> i BC&D Properties <br /> Report, MW Installation and Monitoring <br /> . Project No. 8.1.2 4 <br /> December 17, 1992 i <br /> 1 L; , Page 2 <br /> 2.0 SITE HISTORY <br /> i� <br /> The ground water has been monitored since September 1987 when the three <br /> monitoring wells were installed on site and the initial water samples collected. <br /> Groundwater samples indicated that there was hydrocarbon contamination in <br /> monitoring wells MW-1 and MW-2. These samples were analyzed for benzene, <br /> toluene, total xylenes and ethylbenzene (BTEX) by E.P.A. method 602 and total <br />{ j petroleum hydrocarbons as gasoline (TPH-Gasoline) by E.P.A. method modified <br /> !� 8015. <br /> Since then, the groundwater has been sampled and groundwater gradients have <br /> been measured and calculated for five separate monitoring events. In addition, <br /> groundwater gradients were measured and calculated a number of times between ! <br />€ these monitoring events. <br /> 3.0 SUBSURFACE INVESTIGATION <br /> 3.1 Installation of Monitoring Well MW-4 <br /> i <br />{ On October 13, 1992, GTI and well drillers, Osterberg and Stewart of Modesto, <br /> mobilized drilling equipment to the site and installed MW-4 in the site's f <br /> historical down gradient direction (southwest) from existing MW-2 (Figure 1). <br /> I <br /> The well was drilled using a 10.25 inch outside diameter (6.5 inch I.D.) <br /> j continuous flight hollow stem auger. The boring was advanced to a total depth <br /> of 22 feet below surface grade and groundwater was first encountered at 13 feet c <br /> j below the surface. Soil samples were collected for geological and analytical <br /> I evaluation by continuously soil coring through the aquifer. All soil samples <br /> ,were sealed with aluminum foil, capped, labeled and placed in a cooler at 4° <br /> J C. elsius for transport to the laboratory following Chain of Custody Protocol. Soil I <br /> cuttings were distributed in the open field behind the structure. <br /> I MW-4 was constructed with 2.0 inch diameter, schedule 40 PVC casing with <br /> �{ <br /> flush threaded joints. The casing was advanced to a total depth of 22 feet below <br /> surface grade. The screened interval consists of 0.020 inch perforations extending <br /> from approximately ten feet below above the water table to five feet (22 feet up to k <br /> i 7 feet). Approximately 9 one-hundred pound sacks of number three Monterey <br />! sand was used to form a filtera <br /> p ck about the perforations (22 feet to 6 feet). An � <br /> transition seal was constructed by installing 100 pounds of granular bentonite <br /> that was hydrated with tap water and allowed to expand for a period of one-half <br /> hour. The surface seal was completed by installing a neat cement grout up to <br /> I <br /> l <br />