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FINAL REPORT GEOPHYSICAL INVESTIGATION - CLEARWATER MUNICIPAL CEMETERY SITE FINAL REPORT GEOPHYSICAL INVESTIGATION CLEARWATER MUNICIPAL CEMETERY SITE CLEARWATER, FLORIDA Prepared for Pennoni Clearwater, FL Prepared by GeoView, Inc. St. Petersburg, FL . A Geo iew VV June 13, 2023 Mr. Vince Barnes, P.E. Pennom 5755 Rio Vista Drive Clearwater, FL 33760 Subject: Transmittal of Final Report for Geophysical Investigation Clearwater Municipal Cemetery Site Clearwater, Florida GeoView Project Number 39264 Mr. Barnes, GeoView, Inc. is pleased to submit the final report that summarizes and presents the results of the geophysical investigation performed at the above referenced site. Ground penetrating radar was used to determine the presence and locations of possible graves within a designated area of the site. GeoView appreciates the opportunity to have assisted you on this project. If you have any questions or comments about the report, please contact us. Sincerely, GEOVIEW, INC. 1 71 Lr Christopher Taylor, P.G. Vice President Florida Professional Geologist Number 2256 A Geophysical Services Company 57091st Avenue South Tel.: (727) 209-2334 St. Petersburg, FL 33707 Fax: (727) 328-2477 2 1.0 Introduction A geophysical investigation was conducted at Clearwater Municipal Cemetery Site located at 1300 South Myrtle Avenue in Clearwater, Florida. The purpose of the investigation was to use geophysical methods to determine the possible presence of unmarked graves within the survey area. It was reported by others that unmarked grave sites may be located in the vicinity of a storage shed and planned dumpster area at the property. Historical records indicate that grave sites may be located below the storage shed building and possibly elsewhere around the structure. The area of investigation is approximately 94 feet by 55 feet (ft) including a storage shed and a dumpster containment structure and is shown on Figure 1. Four grave site markers were present within the survey area which is adjacent to numerous existing grave plots to the west and east. The survey was performed on May 25, 2023. 2.0 Description of Geophysical Investigation The geophysical investigation was conducted using ground penetrating radar (GPR). The GPR survey was conducted along transects aligned east to west, spaced one foot on center. Additional transect lines were collected in the area of the dumpster and along north to south lines to further identify previously identified grave anomalies. The GPR data was collected along two-dimensional (2-D) parallel transects which were then processed into a three-dimensional (3-D) depth slices to facilitate high-resolution analysis of the GPR data. The locations of the GPR survey area and transect lines are shown on Figure 1. In the area within the dumpster storage structure, the GPR data was conducted in a reconnaissance mode rather than along set parallel transects. The locations of the lines collected in reconnaissance mode are not shown on the figures. The survey was conducted using a SIR 4000 GSSI radar system with a 350 HS-megahertz(MHz) antenna. A time range setting of 40 nanoseconds (ns)was used for the investigation. This setting provided information to an estimated depth of 5 to 6 ft below ground surface (bgs). A description of the GPR technique and the methods employed for archaeological site characterization studies is provided in Appendix A2.2. A discussion of the field methods used to generate the report Figure 1 is provided in Appendix A2.1. 3.0 Survey Results The results of the GPR survey are shown on Figure 1. Plan view depth slices of the GPR data at varying depths are provided in Figures 2 through 5. Analysis of the GPR data showed the presence of multiple suspected graves at the site. The possible gravesites were characterized on the 2-D data by consistent parabolic reflections and an increase in amplitude of the GPR signal. The graves were 3 identified on the 3-D data by localized changes in amplitude of the GPR signal across several adjacent transects. Four of the suspected graves were associated with visible markers and are considered known graves. These are shown in green on the figures. The GPR identified 14 suspected graves that did not have any visible marker. These areas are shown in blue on the figures. They were all located along the western and southern boundary of the survey area. The GPR did not identify any suspected graves within the building area, dumpster, or areas north and east of the building. Examples of the 2-D data across several suspected graves are provided in Appendix 1. A discussion of the limitations of the GPR technique in archaeological site characterization studies is provided in Appendix 2.3. APPENDIX 1 FIGURES AND EXAMPLES OF GPR DATA COLLECTED AT THE PROJECT SITE s 1i 1 y r - Dumpster (This area was scanned In reconnaissance mode) 1 11 Its} s ,v r 71 ZT Sign- - .{ �— r m SEINE! r}\l m ~— ( BUILDING '_Sha non 77 f Scarborough - { - 1 EXPLANATION FIGURE 1CLEARWATER MUNICIPAL CEMETERY SITE -----------f-= GPR TRANSECTS1300 SOUTH MYRTLE AVENUE Vi SITE MAP CLEARWATER,FLORIDA KNOWN GRAVES WITH NAME MARKERS SHOWING RESULTS PROJEC SUSPECTED UNMARKED GRAVES T: 0 10• V M OF GEOPHYSICAL PENNONI DAINVESTIGATION CLEARWATER,FLORIDA 0TE SCALE:i"=10'APPROXIMATE 06/10/20 f s s � u � ft t f f r - Dumpster 5 i FF 61( —_ Meter IT -. r m =- N r Scarborough _ _Mason t� 411 si .1 EXPLANATION FIGURE 2CLEARWATER MUNICIPAL CEMETERY SITE -----------f-= GPR TRANSECTS 1300 SOUTH MYRTLE AVENUE -------- Vi GPR SLICE OF CLEARWATER,FLORIDA KNOWN GRAVES WITH HEADSTONES AT DEPTH OF JPROJECT: 0 10• — PENNONI 09264 SUSPECTED UNMARKED GRAVES 0 TO 1 FEET CLEARWATER,FLORIDA DATE: SCALE:V=10'APPROXIMATE 06/13/23 ,.Al4 1 �j ��.� f� - 3 '�11�_ i} '� ' ,I z.= •_ r t r {tr frt t 1x•ti, r f { �I, s i Dumpster r ,f x 57` i 60 - ry m r m -Shannon �} ir, y , Sign Scarborough - tn - �tF�: EXPLANATION FIGURE 3CLEARWATER MUNICIPAL CEMETERY SITE -----------f' GPR TRANSECTS 1300 SOUTH MYRTLE AVENUE -------- V GPR SLICE OF CLEARWATER,FLORIDA KNOWN GRAVES WITH HEADSTONES AT DEPTH OF PROJECT: PENNONI 09264 o to' SUSPECTED UNMARKED GRAVES V 1 TO 2 FEET CLEARWATER,FLORIDA DATE SCALE:V=10'APPROXIMATE 06/13/23 of gw t`�tr�t`r s,° ) r� Dumpster Ir is f�rl - c, f - �f �sr 57s — y� 1) - 1`z'1^' - r - Is' t t li pi - { tt��Scarborough l .1 EXPLANATION FIGURE 4CLEARWATER MUNICIPAL CEMETERY SITE -----------f= GPR TRANSECTS 1300 SOUTH MYRTLE AVENUE -------- Vi GPR SLICE OF CLEARWATER,FLORIDA KNOWN GRAVES WITH HEADSTONES AT DEPTH OF PROJECT: 0 10• '� PENNONI 09264 SUSPECTED UNMARKED GRAVES V 2 TO 3 FEET CLEARWATER,FLORIDA DATE: SCALE:V=10'APPROXIMATE 06/13/23 Y ttJt t;S ' z, Dumpster �,......... 57, s soa f - - ii Water tel - ._ m D {` -Shannon � - - - �t<�' EXPLANATION FIGURE 5CLEARWATER MUNICIPAL CEMETERY SITE -----------f-= GPR TRANSECTS 1300 SOUTH MYRTLE AVENUE -------- ° GPR SLICE OF CLEARWATER,FLORIDA KNOWN GRAVES WITH HEADSTONES AT DEPTH OF PROJECT: PENNONI 09264 o to' SUSPECTED UNMARKED GRAVES v 3 TO 4 FEET CLEARWATER,FLORIDA DATE: SCALE:V=10'APPROXIMATE 06/13/23 R 0.0 I I I I 5.0 I I I I 10.0 I I I I 15.0 20.0 25.0 30.0 35.0 4 0 45A 50.0 55.0 ft I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I ,r , �r 1.00 n s fl { j a 3.00 4.00Aff y h Suspected Graves ' I Suspected Graves Ll 03 Ai"imAXILI, i i � riPi GPR TRANSECT 104 AcRoss SUSPECTED GRAVES 0 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 90.0 95.0 50.0 55.0 fi0.0 fi5.0 ]0.0 ]5.0 00.0 05.0 90.0 0 I I I I I I I I I I I I I I I I I I I I �L 1fio 3,t 2.o0 t 3.00 ­0 �„ Known Known �� Suspected Grave Graves ; y Soo � '' Grave GPR TRANSECT 56 KNowN GRAVES AND A SUSPECTED GRAVE A2-1 APPENDIX 2 DESCRIPTION OF GEOPHYSICAL METHODS, SURVEY METHODOLOGIES AND LIMITATIONS A2.1 On Site Measurements The measurements that were collected and used to create the site map were made using a fiberglass measuring tape and a Trimble Geo7x GPS. The degree of accuracy of such an approach is typically sub-foot. A2.2 Ground Penetrating Radar Ground Penetrating Radar (GPR) consists of a set of integrated electronic components which transmits high frequency (200 to 1500 megahertz [MHz]) electromagnetic waves into the ground and records the energy reflected back to the ground surface. The GPR system consists of an antenna, which serves as both a transmitter and receiver, and a profiling recorder that both processes the incoming signal and provides a graphic display of the data. The GPR data can be reviewed as both printed hard copy output or recorded on the profiling recorder's hard drive for later review. GeoView uses a GSSI GPR system. A GPR survey provides a graphic cross-sectional view of subsurface conditions. This cross-sectional view is created from the reflections of repetitive short-duration electromagnetic (EM) waves that are generated as the antenna is pulled across the ground surface. The reflections occur at the subsurface contacts between materials with differing electrical properties. The electrical property contrast that causes the reflections is the dielectric permittivity that is directly related to conductivity of a material. The GPR method is commonly used to identify such targets as underground utilities, underground storage tanks or drums, archaeological features, buried debris, voids, rebar or geological features. The greater the electrical contrast between the surrounding materials (earth or concrete) and target of interest, the greater the amplitude of the reflected return signal. Unless the buried object is metal, only part of the signal energy will be reflected back to the antenna with the remaining portion of the signal continuing to propagate downward to be reflected by deeper features. If there is little or no electrical contrast between the target interest and surrounding earth materials it will be very difficult if not impossible to identify the object using GPR. A GPR survey is conducted along survey lines (transects),which are measured paths along which the GPR antenna is moved. Electronic marks are placed in the data by the operator at designated points along the GPR transects. These marks allow for a correlation between the GPR data and the position of the GPR antenna on the ground. A2-2 Depth estimates to the top of the target is determined by dividing the time of travel of the GPR signal from the land surface to the top of the GPR signal reflection associated with the debris by the velocity of the GPR signal. The velocity of the GPR signal is usually obtained from published tables of the GPR signal traveling through unsaturated soils (4 to 6 nano-seconds per foot two-way travel time). The accuracy of GPR-derived depths typically ranges from 20 to 40 percent of the total depth. The analysis and collection of GPR data is both a technical and interpretative skill. The technical aspects of the work are learned from both training and experience. Interpretative skills for debris studies are developed by having the opportunity to compare GPR data collected in numerous settings to the results from confirmatory studies performed at the same locations. A2.3 Limitations The ability of GPR to collect interpretable information at a project site is limited by the attenuation (absorption) of the GPR signal within the subsurface materials. Once the GPR signal has been attenuated at a particular depth,information regarding deeper features will not be obtained. GeoView can make no warranties or representations of the conditions that may be present beyond the depth of investigation or resolving capability of the geophysical equipment or in areas that were not accessible to the geophysical investigation.