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GEOPHYSICAL SURVEY REPORT

PROPOSED COLUMBARIUM

JEFFERSON BARRACKS NATIONAL CEMETERY

ST. LOUIS COUNTY, MISSOURI

TASK ORDER NO. 00100

CONTRACT W912P9-14-D-0517

Prepared for:

CDG ENGINEERS, INC.

St. Louis, Missouri

Prepared by:

GEOTECHNOLOGY, INC.

St. Louis, Missouri

Geotechnology, Inc. Project No. J029048.01

April 6, 2017

J029048.01

PROPOSED COLUMBARIUM

JEFFERSON BARRACKS NATIONAL CEMETERY

ST. LOUIS COUNTY, MISSOURI

TASK ORDER NO. 00100, CONTRACT W912P9-14-D-0517

TABLE OF CONTENTS

Page

1.0 INTRODUCTION

1.1 Site Description

1.2 Scope of Work

2.0 GEOPHYSICAL METHODS

2.1 Electrical Resistivity

2.2 Seismic Refraction

3.0 GEOPHYSICAL DATA ACQUISITION

3.1 Site Grid

3.2 Electrical Resistivity Data Acquisition

3.3 Seismic Refraction Data Acquisition

4.0 GEOPHYSICAL DATA PROCESSING

4.1 Electrical Resistivity Data Processing

4.2 Seismic Refraction Data Processing

5.0 RESULTS AND INTERPRETATION

TABLES

Page Table 1 - Ranked Priority of Some Focal Points

ILLUSTRATIONS

Plate Site Location and Topography Geophysical Survey Line Locations Electrical Resistivity Profiles Seismic Refraction Profiles Geophysical Data Interpretations Site Plan with Interpreted Features

APPENDIX

Appendix Site Photographs A Limitations of Report B

J029048.01

PROPOSED COLUMBARIUM

JEFFERSON BARRACKS NATIONAL CEMETERY

ST. LOUIS COUNTY, MISSOURI

TASK ORDER NO. 00100, CONTRACT W912P9-14-D-0517

1.0 INTRODUCTION

1.1 Site and Project Description. The geophysical survey was performed to estimate the type of soil, depth to top of bedrock, and explore for possible karst solution features within bedrock for a proposed columbarium within Jefferson Barracks National Cemetery in St. Louis County, Missouri. The site is located in the southwest quadrant of the intersection of Miravalle Drive and Gentry Road. A site location map is shown on Plate 1 and a site plan is shown on Plate 2. The survey area is generally bounded by Miravalle Drive to the north, Gentry Road to the east, grave sites to the south and a drainage feature to the west. Presently, the survey area is undeveloped and the ground cover is comprised of mowed grass. A southwest trending drainage feature is present in the southern portion of the site. The drainage structure is comprised of a buried reinforced concrete pipe that drains from an inlet east of the site to an outlet in the western portion of the site. The ground surface in the northern portion of the site slopes gently downward towards the drainage feature to the south, and the ground surface in the southern portion of the site slopes gently downward towards the north. Photographs of the site and field investigation are included in Appendix A.

Site-specific geotechnical data from drilling have not been acquired for this project, however, published data indicates that the area is underlain by Mississippian-aged limestone of the St. Louis Formation.1 This formation is highly susceptible to karst solutioning and sinkholes have been reported at other locations within Jefferson Barracks Cemetery.

1.2 Scope of Work. The scope of work included collecting electrical resistivity data;

collecting seismic refraction data; processing and interpreting the data for soil type, depth to top of rock, and possible karst solution features; and preparing this report.

2.0 GEOPHYSICAL METHODS

2.1 Electrical Resistivity. The electrical resistivity survey method is a surface geophysical technique which typically involves measuring the apparent resistivity of the subsurface by inducing current into the subsurface with two current electrodes (a current dipole) and measuring the resulting ground voltage with two potential electrodes (a voltage dipole). A dipole-gradient mixed

1 Brill, K.G. Jr., 1991, Geologic Map of St. Louis City and County, Missouri, Missouri Department of Natural

Resources-Division of Geology and Land Survey.

CDG Engineers, Inc. J029048.01 array was used for this survey, which combines elements of a dipole-dipole array and gradient array.

The dipole-dipole array is performed by separating the current and voltage dipoles along a line and taking measurements at various separations between the dipoles. Greater distance between the current dipole and the voltage dipole results in greater depths of the measured electrical field.

Additional readings are taken using a variety of dipole lengths. Gradient array data are added by separating the current electrodes and positioning the voltage dipole at various locations along a line between the electrodes. By taking readings using dipole and gradient arrays at successive locations along a survey line, a profile of subsurface resistivity data is recorded beneath the survey line.

The apparent resistivity data are modeled to obtain actual resistivity values and depths of subsurface features.

The resistivity values of geologic materials are based on many factors including the conductivity of the matrix, porosity, fracture/void density, and water content. Furthermore, resistivity values vary on a scale of orders of magnitudes and are often represented using a logarithmic scale. Typically, clay will exhibit low resistivities, ranging between 1 and 100 ohm-meters (ohm-m). Limestone rock may exhibit a broad range of resistivities ranging between 50 and 107 ohm-m. Karst features may be detected within limestone bedrock because clay-filled solution features often exhibit low-resistivity values, and voids often exhibit high-resistivity values. Typically, karst features are represented by low and/or high resistivity values, while limestone is represented by comparatively intermediate resistivity values

2.2 Seismic Refraction. The seismic refraction tomography method involves the use of compressional waves to develop a two-dimensional profile of subsurface geologic units based on the velocity with which geologic materials transmit seismic waves. Seismic refraction procedures typically include generating seismic waves at or near the ground surface. The seismic waves travel from the source through the subsurface along a variety of paths including refractions along interfaces between soil or rock layers of different seismic velocities. The seismic waves arriving at the surface are recorded at various distances from the source using geophones. The seismic wave arrivals at the receivers are digitally recorded with a seismograph.

The data are interpreted by analyzing the differences in elapsed time from the shot to detection of the seismic waves at various distances from the source. A reconstruction model of subsurface layering is made based on the arrival times of the seismic energy. Refraction tomography is a processing procedure in which the data are modeled to produce profiles of contoured velocity variations with depth.

3.0 DATA ACQUISITION

3.1 Site Grid. Geophysical data were collected along 12 survey lines, indicated as Lines 1 through 12. The lines are shown on Plate 2 with respect to the footprint of the proposed columbarium. The locations of the survey lines were established to provide useable geophysical data to depths below top of bedrock, anticipated to be approximately 30 feet as reported by the client. The survey lines were established using a Trimble GeoXH differential GPS system. The survey lines were approximately 540 feet long and established in a rectangular fashion oriented north-south with a base line anchored approximately 45 feet north of eastbound Miravalle Road.

Line 1 is positioned approximately 7 feet west of Gentry Road and each successive line was parallel and located 10 feet to the west. The southern limits of the survey lines were variable due to the presence of gravesites within the survey area. The geophysical data are reported using the “0-foot” base line as the north boundary of the survey area.

3.2 Electrical Resistivity Data Acquisition. Electrical resistivity data were collected on

March 1 through 8, 2017. Survey Lines 1, 2, and 7 through 12 were collected using 56 electrodes spaced 9.8 feet (3 meters) apart for a total line length of approximately 541 feet. Lines 3 through 6 were collected using 45 electrodes spaced approximately 9.8 feet (3 meters) apart for total line lengths of approximately 433 feet.

The electrical resistivity data were collected using a SuperSting-R8 earth resistivity meter, manufactured by Advanced Geosciences, Inc. (AGI). Electrodes that displayed high resistance at the surface were treated with salt water to provide better conductivity with the near surface materials which resulted in improved current generation and useable voltage measurements. In general, contact resistances at the electrodes were below 1,000 ohms, except for a few readings between 1,000 and 2,000 ohms in rocky soil conditions. Electrode elevations were measured using an optical level and tied to a temporary NAVD882 datum point established on Gentry Road by Bowen Engineering and Surveying, Inc.

3.3 Seismic Refraction Data Acquisition. Seismic refraction data were collected on February 23 through 27, 2017. Data were collected using spreads of 24 geophones spaced 10 feet apart for spread lengths of 230 feet. As shown on Plate 2, refraction data along each survey line were collected such that the resulting data profiles would generally be centered over the location of the proposed columbarium. The length of refraction coverage along each line is less than the electrical resistivity coverage, therefore, the refraction data begins south of the “0-foot” base line and ends north of the south terminus of the longest resistivity arrays.

Refraction data collected on Lines 2 through 9 were collected using two spreads having a total length of 460 feet, except for Lines 3 through 6 which were shortened to approximately 430 feet due to the presence of grave sites. Lines 1, and 10 through 12 were collected using one, 230-foot, spread each.

The seismograph used for this survey was a 24-channel Geometrics Geode. Refracted energy was imparted at five to seven “shots” along each spread, comprised of end shots and multiple mid-spread shots. At each shot location, seismic energy was generated by firing an 8-gauge, 400-grain, black-powder blank into an approximately 1.5-foot deep hole using a

2 North American Vertical Datum of 1988 (NAVD88).

Buffalo Seisgun. The velocity contours at the southern 40 feet of Line 9 were suspect due to a poor shot record collected near standing water within the drainage feature. Therefore, the refraction data at the southern end of Line 9 were not as reliable as the remainder of the dataset. Geophone elevations were measured using an optical level and tied to a temporary NAVD88 datum point established on Gentry Road by Bowen Engineering and Surveying, Inc.

4.0 DATA PROCESSING

4.1 Electrical Resistivity Data Processing. Electrical resistivity data were processed using EarthImager 2D by AGI. The following general processing routine was followed for each resistivity profile:

Removal of negative data and spikes Load elevation data Perform initial inversion Review the data misfit histogram and remove misfits greater than 50 percent Perform final inversion

In general, appropriate iterations for the initial and final inversions were selected based on the presence of consistently low variations in root-mean-square (RMS) error and position early on the asymptotic minimum plot. The final values for iteration number, RMS error, and the L2 comparison statistic (sum of weighted, squared differences between observed values and values predicted from the model) are presented with each resistivity profile on Plate 2. The final inversions were exported as .xyz files and contoured for display in Surfer 13 (Golden Software).

4.2 Seismic Refraction Data Processing. Profiles of seismic velocities were generated based on the arrival times of the seismic waves. The data were processed by picking first-break arrival times at each geophone for each shot. The first-break picks were plotted and reviewed for parallelism and end-time equivalencies. The first-break times were input into the SeisImager tomography software (Geometrics, Inc.) which was used to produce the velocity section based on predictive modeling of the first-break arrivals and subsurface ray paths. A three-layer input model was used to initiate the inversion process.

5.0 RESULTS AND INTERPRETATION

The electrical resistivity data collected on Lines 1 through 12 are presented on Plate 3.

Exhibited on the profiles are soil resistivity values of generally less than 30 ohm-m and bedrock resistivity values ranging between approximately 700 ohm-m to greater than 100,000 ohm-m. The lower bedrock resistivity values are likely associated with weathered zones or solution-widened joints, bedding planes, or cavities filled with soil or water. The higher bedrock resistivity values are likely associated with competent bedrock, however, these zones could also be related to the presence of air-filled voids.

Seismic velocity profiles of the seismic refraction data collected on Lines 1 through 12 are presented on Plate 4. Based on our review of the raw shot records, the near surface direct arrivals through the shallow soil layer exhibited a velocity of approximately 500 ft/s and the bedrock refractors exhibited a velocity of approximately 15,000 to 16,000 ft/s. An intermediate layer or layers were occasionally observed in the shot records. Commonly, an intermediate layer may be present between layers of high velocity contrast such as the 500 ft/s soil layer and 15,000 ft/s bedrock layer, even if not observed in the shot record. These non-detected intermediate layers are called “hidden layers” and can cause erroneously shallow depth to bedrock interpretations. Even though a three-layer model was used as input to the tomographic inversion, the depth to rock that can be interpreted from the tomographic profiles should be calibrated to boring data.

In the absence of boring data, we used electrical resistivity data to ascertain an approximate depth to bedrock. The resistivity data was reviewed for locations at which the contours between the low resistivity soil and high resistivity bedrock were closely spaced, which likely signifies the presence of an interface between soil and bedrock. Closely spaced resistivity contours were observed at the suspected top of bedrock interface on Line 1 (210 to 150 feet from the north base line), Line 11 (200 to 240 feet from the north base line), and Line 12 (190 to 230 feet from the north base line). Based on the velocity contours that aligned with the suspected top of bedrock at these locations, an average velocity contour of 13,000 ft/s was calculated and used to represent top of bedrock across the seismic refraction profiles.

Variations of the velocity contours were observed below the interpreted top of bedrock.

Velocity contours that broaden and dip downward may indicate the presence of lower velocities which could be related to the presence of weathered zones or karst features.

The results of the data analysis for the electrical resistivity and refraction data are combined and shown on Plate 5. The data are presented on the resistivity profiles and include the refraction contours at and below interpreted top of bedrock. Interpreted features shown include top of bedrock, low resistivity zones below top of bedrock, and low velocity zones below top of bedrock.

The interpreted top of bedrock was derived from the 13,000 ft/s velocity contour at locations where refraction data is available and extrapolated based on the trends observed in the resistivity contours at locations beyond the refraction data. The depth to bedrock at the southern 40 feet of refraction data on Line 9 were interpreted based on the trend in the resistivity data due to the poor seismic shot record at that location. The low resistivity and low velocity zones shown below top of bedrock could be related to weathered bedrock or karst features.

In addition, possible points of focus for future exploration within the zones of interest, i.e.

focal points, are also shown on the interpreted profiles. The focal points were selected based on localized low resistivity or velocity values, or localized and narrow depressions within the contours.

The focal points are also shown on the site plan on Plate 6 with possible trends or connected features indicated with dashed lines. Some focal points are numbered with our ranked priority for exploration: number 1 being the highest ranked priority. The focal point assigned priority number 6, was selected because high resistivity values coincided with a zone of low velocities within bedrock, which we suggested be explored for the potential presence of voids. In addition, this location was the location at which the resistivity contours on the suspected top of bedrock were used to calibrate the refraction data and will be helpful for corroborating both datasets.

TABLE 1

Ranked Priority of Some Focal Points

Prioritization (Focal Point

No.)

Line

Distance from North Base Line (ft)

Easting* (ft)

Northing* (ft)

Elevation (ft)

Depth (ft)

Description

1 1 175 879890.9100 970444.0930 414 36

Depression on interpreted bedrock surface. Low resistivity zone centered at focal point. Low velocity zone and low resistivity zone continue downward to the depths explored.

2 9 190 879811.9715 970435.5894 386 59

Resistivity contours bend sharply downward from top of bedrock to focal point. Overlies zone of high resistivity (>40,000 ohm-m).

3 10 410 879822.3683 970200.2408 397 39

Low resistivity zone centered at focal point. Low velocity zone and low resistivity zone continue downward to the depths explored.

Appears related to downward percolation of water from drainage feature.

4 8 246 879827.7891 970366.2965 376 69

Mid-point of a broad depression exhibited by the resistivity contours and is within a low velocity zone within bedrock.

5 4 116 879857.0784 970500.3886 405 43

Low velocity zone and low resistivity zone within bedrock.

Low resistivity zone continues downward to the depths explored.

6 11 210 879795.1465 970398.7911 384 60

High resistivity (>200,000 ohm-m) and low velocity zone within bedrock, which suggests potential presence of voids. Also, location at which resistivity contours on the suspected top of bedrock were used to calibrate the refraction data. Boring will be helpful for corroborating both datasets.

*Northings and Eastings provided in NAD 83, State Plane Missouri East Zone.

SITE

4,0002,000

SCALE IN FEET

Proposed Columbarium

AND TOPOGRAPHY

SITE LOCATION

St. Louis County, Missouri Jefferson Barracks National Cemetery

Drawn By: WAH

Date: 3-15-17

PLATE 1Project Number J02904801

NOTES

1. Plan adapted from 7.5 minute U.S.G.S. maps for Oakville and Webster Groves, Missouri quadrangles, last revised in 2015.

Ck'd By: DWL

Date: 4-5-17

App'vd By: DMS

Date: 4-5-17

GENTRY ROAD

M

IR

AVALLE R

O

AD

Area of Proposed Columbarium

LINE 12

LINE 11

LINE 10

LINE 9

LINE 8

LINE 7 LINE 6

LINE 5

LINE 4

LINE 3

LINE 2

LINE 1

NORTH

BASE LINE

(0 ft)

541 ft

SCALE IN FEET

0 50 100

Proposed Columbarium

SURVEY LINE LOCATIONS

GEOPHYSICAL

St. Louis County, Missouri Jefferson Barracks National Cemetery

Drawn By: WAH

Date: 3-20-17

PLATE 2Project Number J029048.01

NOTES

1. Plan adapted from "2015 Aerial Imagery for the St. Louis Region" supplied by East-West Gateway Council of Governments.

2. Electrical resistivity lines and seismic refraction lines were located in the field with a differential GPS system.

LEGEND

Electrical Resistivity Line Seismic Refraction Line

Ck'd By: DWL

Date: 4-5-17

Proposed Columbarium

RESISTIVITY PROFILES

ELECTRICAL

St. Louis County, Missouri Jefferson Barracks National Cemetery

Drawn By: WAH

Date: 3-16-17

PLATE 3Project Number J029048.01

NOTES

1. See Plate 2 for locations of Electrical

Resistivity Lines 1 through 12.

Ck'd By: DWL

Date: 4-5-17

SEISMIC REFRACTION PROFILES

St. Louis County, Missouri Jefferson Barracks National Cemetery

Drawn By: WAH

Date: 3-15-17

PLATE 4Project Number J029048.01

NOTES

1. See Plate 2 for locations of Seismic Refraction

Lines 1 through 12.

Ck'd By: DWL

Date: 4-5-17

DATA INTERPRETATIONS

GEOPHYSICAL

St. Louis County, Missouri Jefferson Barracks National Cemetery

Drawn By: WAH

Date: 3-20-17

PLATE 5Project Number J029048.01

NOTES

1. See Plate 2 for locations of geophysical survey lines.

2. Number within Focal Point symbol indicates ranked priority for exploration.

3. Refer to Plate 6 for locations of Focal Points on a Site Plan.

LEGEND

Interpreted Top of Bedrock Base on Refraction Data

Interpreted Top of Bedrock Based on Resistivity Data

Velocity Contours Below Interpreted Top of Bedrock

Zone of Lower Velocity in Bedrock

Zone of Lower Resistivity in Bedrock

Possible Point of Focus within Target Zone (Focal Point)1

Ck'd By: DWL

Date: 4-5-17

GENTRY ROAD

M

IR

AVALLE R

O

AD

Area of Proposed Columbarium

LINE 12

LINE 11

LINE 10

LINE 9

LINE 8

LINE 7 LINE 6

LINE 5

LINE 4

LINE 3

LINE 2

LINE 1

NORTH

BASE LINE

(0 ft)

541 ft

SCALE IN FEET

0 50 100

Proposed Columbarium

INTERPRETED FEATURES

SITE PLAN WITH

St. Louis County, Missouri Jefferson Barracks National Cemetery

Drawn By: WAH

Date: 3-20-17

PLATE 6Project Number J029048.01

NOTES

1. Plan adapted from "2015 Aerial Imagery for the St. Louis Region" supplied by East-West Gateway Council of Governments.

2. Electrical resistivity lines and seismic refraction lines were located in the field with a differential GPS system.

LEGEND

Electrical Resistivity Line Seismic Refraction Line Focal Point of some Interpreted Features - Numbers Indicate Ranked Priority for Exploration Dashed Lines Indicate Possible Relationship Between Interpreted Features

Ck'd By: DWL

Date: 4-5-17

APPENDIX A

SITE PHOTOGRAPHS

Proposed Columbarium - Jefferson Barracks National Cemetery J029048.01

Photograph 1 - View of the project site to the north from the southwest corner. Note the location of the culvert.

Photograph 2 - View from northeast area of project site looking south.

Photograph 3 - View from northwest area of project site looking south.

Photograph 4 - View of southern portion of survey area during seismic refraction data collection. View is to the south.

Photograph 5 - View of typical geophone installation.

Photograph 4 - View to the south of the project site during resistivity data acquisition.

Photograph 5 - View of electrode in roadway.

Photograph 6 - View of culvert spillway. Note standing water and riprap.

APPENDIX B

LIMITATIONS OF REPORT

GEOPHYSICAL SERVICES

LIMITATIONS OF REPORT

This report was prepared for the exclusive use of the owner, architect, and engineer for evaluating the project as it relates to the technical aspects discussed herein. It can be made available to prospective contractors for information on factual data only and not as a warranty of subsurface conditions included in this report. Unless other contractual agreements were made, the services described in this report were carried out in accordance with the Terms for Geotechnology's Services that were attached to the proposal.

Geotechnology endeavored to perform the survey in accordance with generally accepted practices of other consultants undertaking similar studies at the same time and in the same geographical area. The findings and conclusions stated herein must be considered not as scientific certainties, but rather as professional opinions concerning the significance of the limited data gathered during the course of the survey. No warranty, express or implied, is made.

The geophysical analyses and conclusions contained in this report are based on the site conditions, project layout, grid size, geophysical data, and interpretive procedures described herein and are for preliminary planning purposes only. Geotechnology can make no interpretation as to the presence of underground features at locations beyond the survey lines.

Geophysical exploration methods are non-intrusive, indirect, and potentially influenced by a variety of natural or man-made conditions. The potential for interpreting the presence or absence of underground objects or voids is based on the recorded data as limited by site conditions and inherent resolution of the method used. While Geotechnology endeavors to provide likely geophysical interpretations based on the data available, interpretations of geophysical data are non-unique and may not represent actual conditions; hence, there will always be the potential of not observing a surface object or void or interpreting the presence of a subsurface object or void where one does not exist.