ARCHIVED REPORTS_PRELIMINARY ASSESSMENT_SITE INVESTIGATION REPORT

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Versar, Inc. April 20, 2000 Page 3 The remaining VMG anomalies evident along the southern and eastern boundaries of the investigation area are attributed to the magnetic effects of the chain-link fence, parked motor vehicles, and trailers. A reconnaissance of this magnetic"shadow" zone using the MD method did not indicate the existence of buried metal in these portions of the investigation area. For further explanation regarding the use of the term "anomalies" and their likely sources, please refer to Appendix A; Contour Map Interpretation. Field Delineation The approximate locations of suspected buried objects in the Vehicle Storage Yard were marked in the field using a combination of spray paint and wire "pin flags". The comers of the large metallic object detected with VMG and MD were flagged, while the estimated center of the two smaller VMG anomalies were flagged. • SECONDARY (CSMS) AREA Within this area the pavement is"bulging", or doming upward, several inches in two locations (not shown). One of the bulges, referred to as"Big Bulge", is approximately 15 feet across; while the other, referred to as "Little Bulge", is only four feet across. The purpose of the investigation of the CSMS area was to characterize what possible buried objects could cause the pavement to bulge in the two locations. The investigated locations within this area were limited to the immediate areas surrounding the two bulges. There were no notable cultural features in the CSMS area which materially affected the investigation of the two "bulge" areas. The first task undertaken was to use the MD method to determine if metallic objects underlie the two bulges. The metal detector results did not suggest the existence of buried metallic objects at either location. The next task undertaken was to obtain two GPR traverses of each of the areas immediately enclosing the suspected buried objects. This was done in an effort to determine the suspected object's approximate size and depth. The GPR results suggested some non-metallic features or objects exist just below the bottom of the pavement at both bulge locations. Such features could range from simply voids to perhaps small empty concrete vaults. STANDARD CARE AND WARRANTY The scope of NORCAL's services for this project consisted of using geophysical methods to characterize the shallow subsurface. The accuracy of our findings is subject to specific site conditions and limitations inherent to the techniques used. The services were performed in a • manner consistent with the level of skill ordinarily exercised by members of the profession currently employing similar methods. No warranty, with respect to the services or products delivered under this agreement, expressed or implied, is made by NORCAL.