64-18 Exhibits - 665 Eagle Rock Avenue.pdf

dielectric constants (dielectric permittivity), a portion of the energy is reflected back. The signal is transmitted to a control unit, displayed on a monitor, and digitally recorded. An image of the subsurface is displayed by plotting two-way travel time of the reflected EM pulse on the vertical axis with the distance traveled along the ground surface plotted on the horizontal axis. The depth of the reflecting anomaly or stratum is then determined by using known soil velocity functions and calculating two-way travel time values. GPR data were collected in 3’ incremental parallel passes within the scope of work. The maximum depth of investigation was approximately five (5) feet at this site due to the dielectric permittivity caused by the moisture content and the composition of the soils. The displayed data were then interpreted by the field technician to determine the potential presence of USTs or other significant subsurface anomalies that are indicated by the presence of large hyperbolic signatures at depth. Smaller objects such as utilities or other objects are indicated by the presence of smaller hyperbolic signatures. If the display indicated the presence of anomaly signatures, the operator would then mark the location for further investigation. 4. Limitations - Limitations encountered during the investigation included steel guard rails, steel post with steel chains and the ground dielectric permittivity that limited maximum GPR depths to five feet (5’). Please note that EM measurement and GPR are remote sensing methods and in some instances, due to interference or other geophysical limitations, do not reveal data which may be indicative of subsurface anomalies. The findings of this investigation should only be used as a tool in evaluating the possibility that anomalous subsurface areas or other hazards are or were once present on the property and should not be considered a guarantee regarding the presence or absence of USTs or other subsurface objects. The presence of the limiting conditions at the Job Site makes it possible that undiscovered subsurface objects may

presence or absence of USTs or other subsurface objects. The presence of the limiting conditions at the Job Site makes it possible that undiscovered subsurface objects may exist. Site conditions and findings The area investigated was limited to the are inside the property boundaries and the sidewalk along Eagle Rock Avenue. No visual indications of a UST were present at the site. No tank-like metal anomalies were present at the site. One (1) tank-like GPR anomaly was located in the sidewalk area measuring approximately 4’ x 6’ and was marked with pink paint. Approximate location and GPR images attached. Conclusion: Without a confirmed tank-like metal anomaly detected in the same location it is not possible to verify that the tank-like GPR anomaly is or is not a potential UST without physical examination by excavating the anomaly. -2-