ARCHIVED REPORTS XR0011750 - Laserfiche WebLink

Home Browse Search

Report: Groundwater-quality Monitoring—January 26,2004: 7500 West Eleventh Street, Tracy, CA. Page 14 plus that in the pores of the filter in the annular space between the casing and the wall of the 8-in. diameter boring. Since no measurable quantity of LNAPL flowed into the well over the 7-day period between November 15 and November 22, it is clear that the 0.5$ ft. of free product found on November 8, 2003 had accumulated in the well at an extremely slow rate. Thus, by corollary, it is reasonable to estimate that only a de minimus volume of LNAPL entered the well over the 14-day period between November 8 and November 22, when groundwater in the well was found to be essentially free of LNAPL. This indicates that the total volume of floating product removed from the well by the three purgings that occurred over that period had a total volume close to that calculated above (i.e., 0.52 . gal.). That estimate is compatible with the field reports made by SJC staff, which indicate that on each of the first two purgings, LNAPL having a total volume of very much less than 1 gallon was recovered from the well and none was recovered at the time of the third Even a one month delay from the third to fourth purging yielded no measurable purging. s thickness of floating product and less than one ounce of recovered LNAPL. The tiny volume of LNAPL that it was possible to recover from Well MW-7 Monitoring on first over period from November 8, 2003 to March 30, ?004 beee Table 3) might, generated by comparing the inspection, be difficult to explain. This difficulty mightg facts about the plume of floating product that are currently known and the small volume ., w the of LNAPL recovered from that well in the cited period.duct mithout neel ht actually presg to ent n the precise magnitude of the volume of floating as originally ally released on the other side of West subsurface, it is clear that the LNAPL gradient from MW-7 had reached that Eleventh Street at a distance of some 24 . B up of �= ter than April 11, 2002• Based on the measurements tluckne�esss rssthe location by no la 2003 SJC estimates that the a Inc 2003a). It is, 'v LNAPL in that well on November 8, SThe San Joaquin Comp Y product present in the surrounding Formation was some 0.33 fl volume order of several thousand , therefore, reasonable to conclude that imeat d to be on the og itand ude subsurface, which volume has been eSt is likely to be orders of mage Joaquin Company lnc• 2003a), before no The San Joaq Product purged from the MW-7 ,,, gallons ( gallonage of p when the soil mass .� greater than the fractional g could be measured in it. However, �` measurable thickness of LNAPLuantit s scalar effects and very limited extent the the a uency properties, drilling effects, the apparent diverge generated around the well aredh edmight be estimated based on the area in which it aced to the relatively minute quantity of LNAPL Of floating product in the subsurface comp is not as is known to have been present er resent on the water table in the well casing removed before it was doe longer incongruous as it might the two volumes illustrates the sigm -spTeadifficulties plumeis between from a widep The apparent divergence b product fr that may be encountered when removal of floating attempted by skimm1ng p roduct from the water table in asmall-diameter well. 1. SJC SJC T. Y �y SJC