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Extended Site Characterization Report: 7500 West Eleventh Street, Tracy, CA, Page 25 R. neighborhood. From depths to groundwater measurements made on November 10, 1997, John P. Cummings &Associates calculated the groundwater flow direction beneath a site at 7777 West Eleventh Street, which has by now been absorbed into Piedmont Lumber's Truss Division's facility at 7675 West Eleventh Street, to be North 22 ° West (John P. Cummings and Associates 1997), On June 14, 2001, ATC Associates Inc. computed the groundwater flow direction near the office building on the Piedmont Lumber site (formerly the site of the Fayette Manufacturing Corporation) to be to the north-northwest (ATC Associates Inc. 2001). The locations of the borings from which depths to groundwater measurements were used to compute the direction of groundwater flow by t==' the respective consultants are shown on Figure 8. The flow directions at those two sites are generally similar to that found beneath the 7474 East Eleventh Street property (i.e., moderately to the west of north). However, the groundwater flow direction reported for Suburban Propane (which is down F; Chrisman Road and due north of the 7500 West Eleventh Street property at 23901 Chrisman Road) by Professional Service Industries, Inc. on February 29, 1996 was computed to be in a direction North 10 ° East (Professional Service Industries, Inc 1996). That computation is in close agreement with the groundwater contour lines shown on ;- Figure 8 that were drawn by SJC from the measurements made on April 11, 2002. A little over one month later, on April 6, 1996, the direction of flow computed for Suburban Propane by Professional Service Industries, Inc. was North 6° West. The direction of groundwater flow computed by SJC from the data gathered on April 11, 2002 has changed little from that computed when a round of groundwater sampling was performed at the site on December 13, 2001, and there had been no significant change in the direction of groundwater flow beneath the subject property since it was first computed from measurements made on May 11, 2000. Based on the groundwater elevation available to date, SJC concludes that the dominant direction of groundwater beneath the subject property at 7500 West Eleventh Street is to 4=;J the north across Eleventh Street but just beyond that road it veers to the east of north so F=,1 that, by the time Carinelo Avenue is reached (see Figure 2 for location), its direction of flow is approximately North 20° East. Evidence from the Suburban propane site suggests -` that the direction of flow in that area may sometimes change to a direction somewhat to the west of north, but such conditions have not been observed from measurements of the depth to groundwater made in the groundwater-quality monitoring wells installed to i> I characterize the 7500 West Eleventh Street site. It is apparent that between the Piedmont Lumber site to the west of the subject property ;J and the Troy's Body and Paint site to the east there is a swale in the groundwater table within which the velocity of the groundwater is slower than is the case to its east or west. This inay be caused by variations in the facies and, thus, the hydraulic conductivity of the - alluvial sediments along a section drawn from west to east through the neighborhood of the 7500 East Eleventh Street property. Alternately, it could be due to the groundwater contours beneath the southern portion of that property being influenced by pumping from a well, such at the one in the vehicle storage yard to the south of Central Valley Collision; 'i located up gradient from the area where the groundwater-quality monitoring wells have SJC