5c_Subsurface_Exploration_Addendum_3.pdf

February 20, 2014 J017065.13

Ms. Margaret Hales CAR 2015 Foundation One Memorial Drive Gateway Tower, Suite 700 St. Louis, Missouri 63102

ADDENDUM NO. 3

SUPPLEMENTAL SUBSURFACE EXPLORATION

PROPOSED VISITOR CENTER ADDITION

JEFFERSON NATIONAL EXPANSION MEMORIAL

ST. LOUIS, MISSOURI

Dear Ms. Hales:

Presented herein are the results of a supplemental subsurface exploration conducted for the referenced project in the area of the proposed visitor center addition.

This report is prepared as an addendum to our April 26, 2013, subsurface exploration report1 for the City Arch River 2015 project. Only items specifically mentioned are modified from the original report; conclusions, recommendations, and limitations contained in the report remain unchanged and apply to this addendum. Foundation recommendations for the proposed addition remain unchanged.

SUPPLEMENTAL EXPLORATION

The supplemental exploration consisted of drilling twelve borings, designated as Borings 3.13a through 3.24a, at the approximate locations shown on Plate 1. The borings were surveyed and staked in the field by Engineering Design Source, Inc., (EDSI) who determined ground surface elevations.

The borings were drilled using an all-terrain CME 750 rotary drill rig equipped with hollow-stem augers. The borings were drilled without sampling to auger refusal at approximate depths of 19.5 to 40 feet. NQ rock coring was used to advance the borings 10 to 12.5 feet below auger refusal. Descriptions of the rock cores are provided on the boring logs presented in Appendix A. Photographs of the rock cores are presented in Appendix B.

Unconfined compression tests were performed on selected rock core samples. Test results are presented on the boring logs.

1 Subsurface Exploration, City Arch River 2015, Jefferson National Expansion Memorial, St. Louis, Missouri;

prepared for City Arch River 2015 Foundation, by Geotechnology, Inc.; Report No. J017065.09 dated April 26, 2013.

CAR 2015 Foundation J017065.13 February 20, 2014

SUBSURFACE CONDITIONS

Based on field observation of drilling effort and auger cuttings, the soil stratigraphy consists of silty clay fill with brick and concrete rubble underlain by silty clay soil. Rough or hard drilling through apparent rubble in the fill occurred in Borings 3.16a, 3.22a, 3.23a, and 3.24a. Auger refusal, possibly on granite pavers, occurred approximately 3 feet above apparent top of rock in Boring 3.23a. Auger refusal in the other borings occurred after penetrating through 1 to 3 feet of highly weathered rock. Auger refusal depths and elevations are presented in Table 1.

Bedrock consists generally of hard, white and gray, finely crystalline, thin-bedded limestone. The rock is highly to slightly weathered with depth. The limestone contains numerous clay partings and clay-filled stylolites that lowered RQD2 values measured in the rock cores.

Depths to competent rock in Table 1 were judged as limestone below zones of core loss or clay seams in the rock cores. A thick core loss, possibly a cavity in the limestone, occurred in Boring 3.19a between depths of 24.7 to 30.2 feet (approximately El 4273 to El 422).

The following attachments are included in and complete this report:

Table 1 - Summary of Supplemental Boring Data Plate 1 - Plan of Site and Boring Locations Appendix A - Logs of Borings 3.13a through 3.24a Appendix B - Rock Core Photographs

2 RQD

3 Elevations used herein are in units of feet and referenced to mean sea level (msl) datum.

J017065.13

TABLE 1

SUMMARY OF SUPPLEMENTAL BORING DATA

Boring No.

Depth (feet) Elevation (feet msl)

Highly Weathered Limestone

Auger Refusal

Apparently Competent Limestone

Ground Surface

Auger Refusal

Apparently Competent Limestone

3.1a 36 37.3 -- 462.3 425 -- 3.2a 36 37 -- 465.7 429 -- 3.3a 34.5 36 44 455 419 411 3.4a 36.5 36.5 36.5 465 429 429 3.5a 35 36 37.5 457.7 422 420 3.6a 22 22 22 449 427 427 3.7a 46 49 -- 461.2 412 -- 3.8a 20 20 -- 461.3 441 -- 3.13a 36 39 41 463.3 424 422 3.14a 37 38 41.6 465.4 427 424 3.15a 35 36 36.3 463.4 427 427 3.16a 29 29.5 30.5 455.4 426 425 3.17a 20 21 21.3 447.3 426 426 3.18a 35 38 38 463.7 426 426 3.19a 21 23 30.2 451.9 429 422 3.20a 36 38 38.4 464.7 427 426 3.21a 35 37 37 463.7 427 427 3.22a 28 30 33.5 455.8 426 422 3.23a 22.3 19.5 27 447.6 428 421 3.24a 38 40 46.5 463.2 423 417

APPENDIX B

ROCK CORE PHOTOGRAPHS

BORING 3.13a

RUN DEPTH, FT RECOVERY, % RQD, %

1 39.0-40.5 83 0 2 40.5-45.5 100 32 3 45.5-49.0 100 21

BORING 3.14a

1 38.0-39.5 83 0 2 39.5-44.5 83 12 3 45.5-48.0 100 0

J017065.13 Arch Visitor Center 3.13a

J017065.13 Arch Visitor Center 3.14a

Core Loss

Core Loss

BORING 3.15a

1 36.0-40.3 100 38 2 40.3-45.3 100 20 3 45.3-46.0 100 50

BORING 3.16a

1 29.5-31.0 94 22 2 31.0-36.0 100 12 3 36.0-39.5 100 31

J017065.13 Arch Visitor Center 3.15a

J017065.13 Arch Visitor Center 3.16a

BORING 3.17a

1 21.0-25.5 91 35 2 25.5-30.5 100 53 3 30.5-31.0 100 67

BORING 3.18a

1 38.0-41.2 100 23 2 41.2-46.2 100 37 3 46.2-48.0 100 24

J017065.13 Arch Visitor Center 3.18a

J017065.13 Arch Visitor Center 3.17a

BORING 3.19a

1 23.0-25.5 67 0 2 25.5-30.5 5 0 3 30.5-Cont. 100 83

BORING 3.19a

3 Cont.-35.5 100 83

J017065.13 Arch Visitor Center 3.19a

J017065.13 Arch Visitor Center 3.19a

Core Loss Core Loss

Core Loss

Core Loss

Core Loss

BORING 3.20a

1 38.0-41.0 86 28 2 41.0-46.0 98 7 3 46.0-48.0 100 17

BORING 3.21a

1 37.0-39.5 100 0 2 39.5-44.5 100 17 3 44.5-47.0 100 13

J017065.13 Arch Visitor Center 3.20a

J017065.13 Arch Visitor Center 3.21a

Core

BORING 3.22a

1 30.0-31.0 100 0 2 31.0-36.0 93 37 3 36.0-40.0 100 17

BORING 3.23a

1 19.5-24.5 43 12 2 24.5-29.5 92 30

J017065.13 Arch Visitor Center 3.23a

J017065.13 Arch Visitor Center 3.22a

Core Loss

BORING 3.24a

1 40.0-44.5 65 15 2 44.5-49.5 82 42 3 49.5-50.0 100 0

J017065.13 Arch Visitor Center 3.24a