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' Mr Nuel Henderson Page 3 of 9 ' approximately 4*C for transport to Argon under chain of custody protocol The samples were analyzed for total petroleum hydrocarbons as gasoline (TPHg) by EPA Method 8015, for ' benzene, toluene, ethylbenzene and xylenes (BTEX) by EPA Method 8020 and for gasoline oxygenate additives including 1,2-DCA and EDB using EPA Method 8260 ' Discrete Groundwater Sampling Discrete groundwater samples were collected from bonngs MW15A and MW15B during drilling ' to determine if contamination was present These data would determine whether or not the deeper well (MW15C) would be drilled with mud-rotary equipment and completed with conductor casing Samples were collected by driving a Hydropunch® groundwater sampler to the desired depth, and exposing the screen to the bed within the formation Small diameter Teflon tubing equipped with a stainless steel check valve was inserted into the rods to the bottom of the sampler Groundwater was brought to the surface by creating a positive displacement effect, and ' dispensed into labeled VOA vials containing hydrochloric acid preservative Subsequently the vials were placed into an ice chest refrigerated to approximately 4° Centigrade, and transported under chain of custody to Argon for analysis ' The groundwater samples were analyzed on 24-hour turnaround for TPH , BTEX and g p Y 8 • oxygenates using the appropriate EPA methodologies ' A Zone and B Zone Well Construction A Zone wells MW15A and MW16A were screened from approximately 35 to 55 feet below ground surface (bgs) B Zone wells MW13B, MW15B and MW16B and were screened from approximately 70 to 80 feet bgs The wells were constructed with 2-inch diameter, Schedule 40 ' PVC casing and 0 020 inch slotted screen The filter pack consisted of #3 silica sand The annular seals contained two to four feet of bentonite overlain by neat cement/bentonite grout to ' the ground surface The monitoring wells were secured at the ground surface with flush mount watertight well boxes and locking well caps Well construction details are depicted on the boring logs contained in Attachment A and summarized in Table 1 ' Mud Rotary Drilling Due to the presence of contaminants in discrete groundwater samples collected from wells MW15A and MW15B, it was decided that MW15C would be drilled using mud-rotary equipment in order to provide the highest degree of protection from cross-contamination From January 17 to January 21, 2003, V&W advanced one soil boring using a mud-rotary drilling ng The location of the well is shown on Figure 2 The surface hole was drilled with a 12 1/4 inch diameter rockbrt to a depth of 90 feet At this point a 6 % inch diameter steel conductor casing fitted with centralizers and lead by a grout shoe was cemented in place After the cement cured, the boring was deepened to a total depth of 121 feet bgs with a 6 inch diameter rockbrt ' 11GZA FSIVOL_11DATA1GROUNDZE-ROEKICLOSUREXRepofts\Add_HSA Mud wells doe