J.6 ICR - Presidents Room - GPR Findings Memo.pdf

INTEGRATED CONSERVATION RESOURCES, INC.

MEMO

To: From:

Desmond Scott, Contracting Officer Architect of the Capitol Desmond.Scott@aoc.gov 202-355-4552

Integrated Conservation Resources, Inc.

63 Flushing Ave Building 303 Suite 606 Brooklyn, NY 11205

Date: Project:

22 November 2024

President’s Room Ceiling Analysis

RE:

Presidents Room Ceiling – Surface Penetrating Radar Assessment

Integrated Conservation Resources, Inc. (ICR) is providing this memo at the request of the Architect of the Capitol. The purpose of this memo is to outline the findings of Surface Penetrating Radar performed at the Press Room, above the Presidents Room, in relation to plaster conditions identified during the Presidents Room Ceiling Phase 1-4 assessment, and as discussed in detail with AOC over several meeting and email exchanges in August-October 2024.

As part of ICR’s Presidents Room Plaster Ceiling Phase 1-4 Report, a phased plan of recommendations was provided that would allow the team to better understand both the root cause of detachment and compromised plaster, as well as if any of the causes of the plaster conditions are ongoing. AOC approved performing Surface Penetrating Radar at the Press Room above the Presidents Room, one of the steps in the first phase of recommendations.

On October 30th, 2024, ICR and Atkinson-Noland and Associates (ANA) performed a site visit to the US Capitol during which Surface Penetrating Radar was performed in the spaces above the Presidents Room, in order to better understand the cross section of the brick vault above the plaster ceiling and identify any anomalies within the ceiling structure. The attached report from ANA outlines the methodology and findings of this assessment.

The Surface Penetrating Radar allowed ANA to identify the location of utility lines as well as map the cross section of the vault. Additionally, several anomalies within the vault were identified, including a steel ring around the perimeter of the room as well as isolated locations of potential internal voiding at the collar joint in the brick vault. As noted in the recommendations of the Phase 1-4 report, the information gained from this assessment is not sufficient to advise on root cause or ongoing issues, However, the information found in this assessment allows the team to make informed decisions on locations and placements of probes and environmental and vibration monitoring systems.

Atkinson-Noland & Associates

2619 Spruce Street

Boulder, CO 80302

303.444.3620

32 Old Slip, 10th Floor

New York, NY 10005

917.647.9530 ana-usa.com

PROJECT REPORT

President’s Room Ceiling Investigations

The President’s Room, S-216 United States Capitol First St. SE Washington, DC

PREPARED FOR:

Integrated Conservation Resources, Inc.

63 Flushing Ave.

Building 303, Suite 606 Brooklyn, NY 11205 212-947-4499 x103 jschork@icr-icc.com

PREPARED BY:

Gary Ogden Atkinson-Noland & Associates, Inc.

President’s Room: Press Room SPR

ANA Job No. 22-193

November 21, 2024

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1. INTRODUCTION

On October 30th, 2024, Gary Ogden of Atkinson-Noland and Associates Inc. (ANA) was onsite at the US

Capitol to conduct nondestructive testing of the ceiling in The President’s Room (Senate Room S-216).

All investigations were performed from above The President’s Room, on the floor of the Press Room (S-

316). Michelle Leach of ICR facilitated site access to the Capitol and assisted ANA during the investigations. This investigation follows previous phases of investigation to further determine the as-built construction of The President’s Room’s vaulted ceiling.

Testing performed by ANA, during this site visit, included surface penetrating radar (SPR). The following report summarizes test locations, methods, and results relating to nondestructive testing of the floor in the Press Room. Figure 1 provides the extent of ANA’s investigation. An image from a previous renovation within the Capitol was used as a reference to help further understand the construction of the vaulted floors.

Figure 1. Plan view of the Press Room (S-316) outlining the approximate extent of ANA’s investigations. Background by others.

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Figure 2. Image of an exposed floor during a previous renovation (not at the Press Gallery). Visible in the image are embedded pipes, the fill material, and the brick vault system. Image provided by ICR.

2. INVESTIGATIVE TESTING (PRESS ROOM)

2.1. Microwave Radar Scanning

Surface penetrating radar (SPR) was used to assess the cross-section of the masonry vault of the

President’s Room as well as portions of the adjacent rooms, by scanning from above in the Press Room.

The SPR method involves the transmission of high frequency electromagnetic radio (radar) pulses into the object of interest and measuring the time elapsed between transmission, reflection from subsurface features, and reception back at the surface radar antenna. A pulse of radar energy is generated on a dipole-transmitting antenna that is placed on the surface of the object of interest. Reflections of the radar energy occur at discontinuities due to changes in the dielectric properties of the underlying material. Void spaces, metal presence, and any distinct change in material dielectric will generate radar reflections due to a change in radar wave velocity at the interface. Scanning was conducted with a

Proceq GP800o unit with stepped frequencies from 200 to 4000 MHz.

The average relative dielectric permittivity of the masonry assemblage was determined by matching the curvature of a hyperbolic reflection in the SPR data using the manufacturer’s software installed on an

Apple iPad as well as matching the shape of the vaulted ceiling in the scan data to Lidar Scanning previously completed by ICR. Determining the relative dielectric permittivity allows for the determination of the radar velocity in the substrate and the correct interpretation of the depth of features in the radar transects. Figure 3, below, provides an example SPR trace recorded from the Press

Room. Annotations indicate the identified features of the floor assembly.

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Figure 3. SPR transect recorded from the floor of the Press Room. The image shows a scan taken from east to west across the floor. Markups highlight the interpretation of the scan including embedded elements within the floor systems as well as the overall construction. The horizontal axis is in feet and inches, the vertical axis is in inches.

Based on the investigation, ANA was able to further determine and refine previous results for the as-built construction of the President’s Room ceiling. The floor system was constructed of tiles with an assumed settling bed on top of a subfloor. Repetitive reflections present at this depth likely indicate a subfloor system with wooden sleepers. Note that the sleepers appear to be orientated in a different direction over the President’s Room versus the entryway, which is why they are not visible for the entire scan. The presence of sleepers in the corridor was inconclusive. The structural system was a two-wythe brick arch system, with fill material above. The adjacent vaulted ceilings have similar structures based on the scanning. These conclusions are similar to the results from the SPR scanning completed previously from below. The major difference was the brick vault thickness was determined to be 8 inches thick (compared to the 12-inch thickness determined from previous phases). A cross-section based on the findings is provided in Appendix A.

Scanning from above also identified the metallic element near the spring line of the vault. During previous phases, the reflection was assumed to be a radial tension ring. Given its depth compared to the other identified utility lines, it further indicates that this is not an embedded utility line. Reflections within the brick vault (dashed yellow line in Figure 3) was also consistent with previous results completed from below. These reflections were typically present on the upper third of the vaulted ceiling and may indicate voiding within the collar joint of the brick vault.

Several lines of embedded utilities, such as gas, electric, or water lines, were identified within the floor system. These utilities were typically 4 to 4.5 inches from the top surface of the floor. The position of the

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Atkinson-Noland & Associates identified utility lines is provided in Appendix B. Additionally, ANA understands the chandelier in the

President's Room was historically gas and is currently hung from the ceiling using the abandoned gas line. The scanning confirmed that an embedded element was present directly over the chandelier, indicating that some of the embedded utility lines are likely historic gas lines.

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Appendix A

Vault Cross Section

BRICK VAULT,

APPROXIMATELY 8" THICK,

TWO WYTHES THICK

WALL

TILE AND SETTING BED, 3"± FILL, MOSTLY SOLIDSUBFLOOR AND SLEEPERS , 3"±

PLASTER CEILING 0.5-1.5" ±

PRESIDENT'S ROOM CORRIDORLANDING

GEOMETRY OF PLASTER

CEILING IN CORRIDOR NOT

DETERMINED

GEOMETRY OF PLASTER

CEILING IN ENTRY WAY NOT

DETERMINED STEEL ANOMALY - SHAPE AND

ORIENTATION UNKNOWN

TYPICAL UTILITY LOCATION,

4-4.5" FROM TOP SURFACE

APPROXIMATE ZONE OF

POTENTIAL INTERNAL

VOIDING AT COLLAR JOINT

IN BRICK VAULT

1'-3" +/-

CEILING OUTLINE AT WALL

EDGE

A tk in so n- N o la nd

A ss o ci at es

, I nc

S p ru ce S tr ee t Bo ul d er

, C O

3.

4.

O ld S lip , 1

0t h flo o r

N ew

Y o rk

, N Y

7.

7.

SCALE:

TITLE

PROJECT NUMBER:

DATE:

DRAWN BY:

CKD. BY:

REVISIONS:

As Indicated

SK1

PRESIDENT'S ROOM

VAULTED CEILING

REV. # DATE

PR

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ID

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11/12/2024

22-193

GDO

DBW

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Appendix B

Plan Layout of Utility Lines

// CONTROLLED //

R ep ro du ce d at th e R ec or ds M an ag em en t a nd

A rc hi ve s B ra nc h (R

M A

B )/A

O C

A rc hi ve s

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PROPERTY OF THE UNITED STATES GOVERNMENT - CONTROLLED UNCLASSIFIED INFORMATION

REPRODUCTION, DISTRIBUTION OR DISSEMINATION OF THESE DRAWINGS, PLANS, DETAILS OR SPECIFICATIONS, IN WHOLE OR IN PART, WITHOUT THE APPROVAL OF THE UNITED STATES GOVERNMENT IS STRICTLY PROHIBITED. VIOLATORS WILL BE PROSECUTED TO THE FULLEST EXTENT OF THE LAW.

Do not remove this notice. Properly destroy documents when no longer needed.

Blank Footer

PROPERTY OF THE UNITED STATES GOVERNMENT - CONTROLLED UNCLASSIFIED INFORMATION

REPRODUCTION, DISTRIBUTION OR DISSEMINATION OF THESE DRAWINGS, PLANS, DETAILS OR SPECIFICATIONS, IN WHOLE OR IN PART, WITHOUT THE APPROVAL OF THE UNITED STATES GOVERNMENT IS STRICTLY PROHIBITED. VIOLATORS WILL BE PROSECUTED TO THE FULLEST EXTENT OF THE LAW.

Do not remove this notice. Properly destroy documents when no longer needed.

Anomaly at 11" deep at crown of vault

BASE DRAWING BY OTHERS.

MARKUPS BY ANA.

NOT TO SCALE.

ALL DIMENSIONS ARE APPROXIMATE.

N

Corridor wall

LEGEND:

Utility Line (4-4.5" deep, typ.)

Unknown Anomaly

Wall Below

Corridor Wall

5' -2

/2

1' -1

0"

17'-1"

0'-5"

6'-9"4'-7"

E .Q

E .Q

9'-11" 2'-8"

1'-6"

E.QE.Q

2'-0"

3'-5"

Center of President's Room below

This utility line, not as conclusive as others indentified