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` BC&D Properties <br /> Report, MW Installation and Monitoring <br /> Project No. 8.1.2 <br /> December 17, 1992 <br /> Page 3 <br /> a. <br /> grade. The well casing was secured with a water tight locking cap encased within <br /> a traffic safe well box. A well construction schematic is attached as Figure 2. <br /> La <br /> 3.1.1 Well Development <br /> After installation, MW-4 was developed by mechanical surging and pumping <br /> with an air lift pump. Due to the lower permeable relatively clay rich aquifer, <br /> very little development water was able to be pumped during the development <br /> process. While pumping, immediate total drawdown occurred and high <br /> 4.0 cloudiness was observed. Some of the development water pumped from the <br /> well was inadvertently spilled on the gravel surface of the parking lot. <br /> Approximately 3 gallons of development water was lost and efforts to recover <br /> 60 this water were unsuccessful. <br /> MW-4's measuring point (top of casing) was surveyed and it's elevation and <br /> relative position referenced to the existing monitoring wells on site. These <br /> elevations were referenced to an arbitrary plane. <br /> 3.2 Geology of Site <br /> The geology of the site was determined from the sediments retrieved with the <br /> split spoon sampling tool. A geologic sample was collected from the S - 7 foot <br /> interval then collected continuously below the 10 foot level. It was observed that <br /> the geology of the MW-4 boring was relatively consistent with previous borings. <br /> A fine grained unit was encountered at 10 feet which extended below 20 feet. <br /> The stratigraphy at the site is composed mainly of silt with varying amounts of <br /> sand and clay (Appendix B-boring log). <br /> i. A very fine to medium grained sand (as referenced to the modified Wentworth <br /> Scale) dominated the shallow geologic sequence just beneath the topsoil. The <br /> sand is generally well graded and showed poor sorting. <br /> Core inspection revealed that the soil did not exhibit the typical evidence of a <br /> reducing environment (i.e., greenish colored). Biological reduction of petroleum <br /> `' hydrocarbons depletes oxygen, creating a reducing environment and causes the <br /> iron to come into a reduced state and exhibit a green color. The absence of this <br /> coloration suggests the absence of petroleum hydrocarbons in the soil. <br />