J.11_Sunland_Park_Levee_Forensic_Geotechnical_Investigation.pdf

kris Typewritten text UNITED STATES SECTION OF THE INTERNATIONAL BOUNDARY AND WATER COMMISSION (USIBWC) FORENSIC GEOTECHICAL ENGINEERING ANALYSIS OF THE SUNLAND PARK LEVEE

EL PASO, TEXAS

CONTRACT No. IBM15C0002

Kenall Project No. 1929 / Contract No. IBM15C0002

Sunland Park Levee Forensic Geotechnical Investigation

Date: July 29, 2016

Status: Final

Contract No. IBM15C0002

Written by:

FINAL

THIS DOCUMENT IS FINAL REPORT RELEASED UNDER THE AUTHORITY OF

KRISHNA D. PRASAD, P.E., TEXAS NO. 91952 ON July 29, 2016. IT IS NOT TO BE

USED FOR CONSTRUCTION, BIDDING OR PERMIT PURPOSES.

KENALL, INC.

TEXAS REGISTERED ENGINEERING FIRM F- 5366

Kris D. Prasad., P.E.

John Rutledge., P.E.

Peter R. Cali, Ph. D., P.E.

Mike Shiflett, P.E.

Mark Ickert, P.E.

Srujan Rao Chikyala, P.E.

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1 INTRODUCTION

1.1 PROJECT DESCRIPTION

1.2 AUTHORITY AND SCOPE OF THE FORENSIC GEOTECHNICAL INVESTIGATION PROGRAM

2 REVIEW OF HISTORIC CONSTRUCTION DOCUMENTS

2.1 BRIEF TIMELINE AND HISTORY

2.2 ORIGINAL DOCUMENTS REVIEW AND SUMMARY

2.3 TECHNICAL ISSUES

2.4 METEOROLOGICAL DATA

3 DATA COLLECTED

3.1 PHOTO DOCUMENTATION AND FIELD VISIT

4 INTERVIEWS

5 FIELD INVESTIGATION

5.1 GENERAL

5.2 GEOPHYSICAL INVESTIGATION

5.2.1 Electromagnetic Survey

5.2.2 Ground Penetrating Radar Survey

5.2.3 Summary and Conclusion

5.3 GEOTECHNICAL BORINGS

5.3.1 General

5.3.2 Survey Data

5.3.3 Sampling Methods

6 LABORATORY TESTING

7 SUBSURFACE CONDITIONS

7.1 GENERAL GEOLOGY

7.2 SOIL STRATIGRAPHY

7.3 LEVEE SURFACE CONDITIONS

7.4 DISPERSIVITY OF SOILS

7.5 GROUNDWATER CONDITIONS

8 RESULTS AND ANALYSIS

8.1 EROSION AND DISPERSIVE SOIL ANALYSIS

8.1.1 Factors Affecting Soil Erosion

8.1.2 Summary and Conclusions

8.2 QUALITY CONTROL ASPECTS OF FILL MATERIAL

8.2.1 Analysis

8.2.2 Summary and Conclusions

9 EXISTING LEVEE ANALYSIS

9.1.1 Embankment Protection

9.1.2 Compliance with FEMA Requirements

9.2 EMBANKMENT AND FOUNDATION STABILITY

9.2.1 General Discussion

9.2.2 Seepage Analysis

9.2.3 Slope Stability Analysis

9.3 SETTLEMENT

9.3.1 Elastic, Consolidation and Secondary Compression Settlements

9.3.2 Settlement Caused by Earthquake Loadings

9.3.3 Shrinkage Settlement

9.3.4 Collapsible Soil

9.3.5 Summary of Results

9.3.6 Compliance with FEMA Requirements

10 REMEDIAL SOLUTIONS

10.1 REMEDIAL CONCEPT NO. 1 – RECONSTRUCTION WITH NONDISPERSIVE SOIL

10.2 REMEDIAL CONCEPT NO. 2 – RECONSTRUCTION WITH LIME AMENDED FILL

10.3 REMEDIAL CONCEPT NO. 3 – ZONED EMBANKMENT

10.4 REMEDIAL CONCEPT NO. 4 – SLOPE BLANKET

10.5 REMEDIAL REPAIR ANALYSES

10.5.1 Seepage Analyses

10.5.2 Slope Stability Analyses

10.5.3 Settlement Analyses

10.6 SUMMARY OF REMEDIAL REPAIR SOLUTIONS

11 CONCLUSIONS & RECOMMENDATIONS

11.1 DISTRESS HISTORY AND PHYSICAL DETERIORATION

11.2 CAUSES OF DISTRESS

11.3 SUMMARY OF IDENTIFIED ISSUES

11.4 RECOMMENDATIONS

12 LIMITATIONS

13 REFERENCES

APPENDICES

APPENDIX A PHOTO DOCUMENTATION

APPENDIX B BORING LOGS AND SYMBOLS AND TERMINOLOGY USED IN BORING LOGS

APPENDIX C LABORATORY DATA SUMMARY SHEET

APPENDIX D GEOPHYSICAL INVESTIGATION REPORTS MAP BOOK

FLAGGED EM31 SURVEY SPOTS FOR GPR INVESTIGATION

APPENDIX E SOIL BORINGS LOCATION MAP

APPENDIX F CALCULATIONS WORKSHEET

APPENDIX G SOIL BORINGS MAPBOOK

APPENDIX H SLOPE STABILITY AND SEEPAGE ANALYSIS

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Kenall Project No. 1929 / Contract No. IBM15C0002 Page 1

EXECUTIVE SUMMARY

The United States Section of the International Boundary and Water Commission (USIBWC) issued in September, 2010 a construction contract to rehabilitate the Sunland Park Levee segments. While construction was completed approximately three years ago, the levee unfortunately has not held up to the standards for durability that were expected after rehabilitation. With the durability in question, the USIBWC procured Kenall to perform the following professional services of a Forensic Geotechnical Engineer: to conduct field investigations laboratory testing, and engineering analysis to provide the USIBWC with a professional opinion on whether the newly constructed levee segments will perform satisfactorily during the 100-year flood event pursuant to 44CFR §65.10. A 100-year flood has a 1% probability of occurring in any given year as defined by the Federal Emergency Management

Agency (FEMA).

Conclusions: Current laboratory testing identified dispersive clay soils within the existing levee embankment along the entire length of analyzed levee. Dispersive clays are highly erodible soils that have contributed to the failures of numerous earthen embankments. Therefore, the analyzed stretch of levee, as currently constructed, does not meet the National Flood Insurance

Program (NFIP) Regulation 44 CFR Section 65.10(b).

Recommendations: Remedial repair through rehabilitation or removal and reconstruction of the levee will be required along the entire length of analyzed levee. The primary levee concern is dispersive clay located within the embankment. The dispersive clays are not located within discreet sections of the levee. Therefore, the entire analyzed Sunland Park Levee will require remediation. Remedial concepts were evaluated and are discussed in the report.

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 2

1 INTRODUCTION

1.1 Project Description

The United States Section of the International Boundary and Water Commission (USIBWC) issued a construction contract to rehabilitate the Sunland Park Levee segments in September, 2010. While construction has been completed for approximately three years, the levee unfortunately has not held up to the durability that was expected after rehabilitation. With the durability in question, the USIBWC procured Kenall to perform the professional services of a

Forensic Geotechnical Engineer to conduct field investigations and to provide the USIBWC with a professional opinion on the cause of the durability concerns and whether the newly constructed levee segments will perform satisfactorily during the 100-year flood event per

44CFR §65.10. A 100-year flood is an event that has a 1% probability of occurring in any given year as defined by FEMA.

1.2 Authority and Scope of the Forensic Geotechnical Investigation Program

Kenall has performed field and laboratory investigations and engineering analysis to detect the causes as well as the process of distress in the respective Sunland Park Levee structures.

The investigations were performed within the limits of the following levee segments as described in the Table 1.1.

Table 1.1 Description of Levee Segments

Levee Segment CW2 CE2

Name of the

Segment

Canutillo Levee Segment, Vicinity of

City of El Paso, El Paso County, Texas

Canutillo Levee Segment, Vicinity of City of El Paso, El Paso County, Texas

Distance

(Approximately)

3.38 Levee Miles 8.45 Levee Miles

Location From the Borderland Bridge along the west bank to the NeMexas Drain

From just upstream of Borderland Bridge along the east bank to the triple box culvert just upstream of the El Paso

Electric Power Plant

Coordinate

System

New Mexico State Plane - Central

3002, NAD83

New Mexico State Plane - Central 3002, NAD83

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 3

Table 1.1 continued

Levee Segment CW2 CE2

Begin X

Coordinate (US

Survey Feet)

E 1,531,896 E 1,532,325

Begin Y

Coordinate (US

Survey Feet)

N 322,399 N 323,014

End X

Coordinate (US

Survey Feet)

E 1,529,827 E 1,547,826

End Y

Coordinate (US

Survey Feet)

N 305,116 N 291,919

Begin Station

(Approximate) 1518 + 56 1511 + 19

End Station

(Approximate) 1697 + 00 1957 + 00

Kenall performed the following tasks at different levels of investigations. The forensic investigation was divided into nine (9) tasks.

1. Geotechnical Design Document and Construction Quality Control Document Review

2. 44CFR §65.10 Levee Criteria

3. Onsite Visit by the Team

4. Geophysical Field Investigation

5. Locating the Boreholes and Surveying

6. Geotechnical Field Exploration

7. Laboratory Testing

8. Analysis of Test Results

9. Remedial Solutions

The present report is organized into twelve (12) sections.

Section 1 provides the introduction, authority and scope of the forensic geotechnical investigation program.

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 4

Section 2 provides the timeline of the events and summary of the historic documents, meteorological data.

Section 3 presents the photo documentation and field visit observations.

Section 4 provides the interview with the USIBWC personnel.

Section 5 provides the details about the field investigation programs, including the geophysical investigation and geotechnical investigations.

Section 6 describes the laboratory testing program.

Section 7 describes the subsurface conditions and geology of the site.

Section 8 provides the analysis of data measured from laboratory tests and engineering analysis.

Section 9 provides the existing levee analysis.

Section 10 provides the remedial concepts.

Section 11 provides the conclusions and recommendations.

Section 12 discusses the limitations of this study.

2 REVIEW OF HISTORIC CONSTRUCTION DOCUMENTS

2.1 Brief Timeline and History

A general time line of events on the Sunland Park Levee is presented in the following paragraphs. Although the actual dates of levee raising construction by USIBWC Operations and

Maintenance (O&M) are not totally clear, the construction by the O&M crews ended on

September 9, 2009. A report by Raba-Kistner Consultants (R-K) titled “Evaluation of

Compacted Fill” was issued August 17, 2010, with the report prepared for S&B Infrastructure.

On December 28, 2010, a Final Technical Memorandum for Geotechnical Explorations of Levee

System Within the Rio Grande Canalization Project, Canutillo Levee Segment, was issued by

S&B Infrastructure (S&B), in association with R-K.

Construction plans for Design of Rehabilitation Improvements for the Rio Grande Canalization

Protective Levee System, Sunland Park Package were signed and sealed on August 25, 2010, by S&B. Conformed specifications for the Sunland Park Package were also signed and sealed on August 25, 2010.

On September 28, 2010, the Notice to Proceed on Construction Contract IBM10C0018 was given to Ultimate Concrete (UC) of El Paso, TX. Quality Control (QC) testing was the

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 5 responsibility of the contractor who retained Archana USA, Inc. (Archana). Archana provided the

QC testing of the project through August 24, 2011. On August 25, 2011, R-K provided QC testing through the end of the project in November 2012. Tetra Tech was retained by USIBWC as the owner’s representative on site but their duties did not include quality assurance testing for USIBWC.

Figure 2.1: Timeline of Events – Sunland Park Levee (December 2008 – November 2012)

Below are the observations of Kenall with respect to the timeline of events:

12/22/2008 - Geotechnical report submitted by R-K.

07/2009 - Design task order issued to S&B.

09/2009 - Levee raising by USIBWC O&M crew ended.

12/09/2009 – Memorandum from R-K to S&B Infrastructure clarifying use and requirements of clay soils in referenced projects, which included the Canutillo, Texas Reaches

04/02/2010 - Evaluation of compacted fill summary report by R-K.

06/02/2010 - Evaluation of compacted fill summary report by R-K.

08/17/2010 - Evaluation of compacted fill revised summary report by R-K.

08/25/2010 - Plans and specifications submitted by S&B.

09/28/2010 - Notice to proceed issued for construction contract IBM10C0018 to

UC.

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 6

04/12/2011 - First day Archana quality control testing was onsite.

08/24/2011 - Last day Archana quality control testing was onsite.

08/25/2011 - First day R-K quality control testing was onsite.

11/02/2012 - Last levee work by UC contractor under IBM10C0018 (based on

Daily Reports by UC).

2.2 Original Documents Review and Summary

Construction daily reports, Quality Assurance/Quality Control (QA/QC) documentation, and

USIBWC’s Summary of Data, and information gained at the USIBWC kickoff meeting for this forensic evaluation were reviewed to assess compliance of the Sunland Park Levee construction with the project specifications, resulting in the following observations:

a) UC was the general contractor, with Archana and R-K providing quality control testing of the construction work. USIBWC retained Tetra Tech as the owner’s onsite representative and to provide construction management services.

b) The specifications stated that USIBWC would not provide confirmation QA testing (Specifications page 35.41.00-19).

c) Contracting Officer's Representative (COR) stated there were numerous field density tests that were outside limits of specifications, and many of these tests were not re-tested for confirmation of additional compaction or moisture adjustment. Subsequent to the kickoff meeting for this forensic evaluation contract, COR provided a spreadsheet summary of field density test results for the levee embankments. The spreadsheet data indicated the areas and dates of construction where no QC tests were taken during earthwork operations. Also, after reviewing the spreadsheet summary, it appeared that of the nonconforming density test results, many, although not all, of the nonconforming tests had been re-compacted and retested. There were numerous nonconforming moisture content test results that do not have confirmation of moisture adjustment and confirmation tests. Therefore, the QC testers may have been more concerned

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 7 with embankment density than moisture content, which would account for the number of nonconforming moisture tests.

d) Construction specifications observed in the contract documents pertaining to optimum moisture content for embankment fill material:

i. Optimum moisture content 0% to 2% points above the optimum moisture content until permanently covered. (Specifications Page 35.41.00 - 15).

ii. 0% to +3% optimum moisture content (Specifications Page 01.46.00 - 7, Plans - Sheet No. 06.02).

e) Construction specifications observed in the contract documents pertaining to compaction for embankment fill material:

i. 95% dry density of standard proctor density (ASTM D698) (Specifications

Page 01.46.00 - 7, Plans - Sheet No. 06.02).

f) Based on 0% to +2% optimum moisture content and 95% dry density standard proctor considered as passing criteria, 28.4% of the reported embankment density tests did not meet the specifications. Based on the QC testing summary spreadsheet, USIBWC did not receive all of the density test results.

g) Based on 0% to +3% optimum moisture content and 95% dry density standard proctor considered as passing criteria, 0.4% of the reported embankment density tests did not meet the specifications.

h) Dispersivity of soil - ND1 or ND2 (ASTM D4647 - Pinhole Test); Grade 2 (ASTM

D6572 Crumb Test). One per pit and one per pit/subgrade-blend was the required specification frequency for both crumb test and pinhole test.

(Specifications Page 01.46.00 - 7, Plans - Sheet No - 03.01).

i. Review of quality control documents indicated that only two crumb tests were reported. The two crumb tests reported were performed by R-K and indicated nondispersive soil.

i) The plans and specifications were clear to the exclusion of dispersive clay material from fill used for the levee embankment. (See Specification PART 2 –

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 8

Materials & Equipment, 2.1 Materials A. Fill Materials (1); page 35.41.00-7 of

Addendum No. 1 – August 25, 2010.)

j) Levee embankment was specified to be an impervious material consisting of a lean clay (CL); Plasticity Index (PI) greater than 15 and less than 30; Liquid Limit

(LL) not exceeding 45. Also, soil must be free from masses of organic matter, sticks, branches, roots, and other debris, including hazardous and solid waste.

Gradation requirements of 100% of the dry material passing the 3 inch sieve and

50% passing the #200 sieve. (Specifications Page 01.46.00 - 7, Plans - Sheet No

- 03.01). Review of USIBWC quality control summary of test results revealed the following:

i. Based on the QC testing summary, 7% of the reported embankment gradation and Atterberg Limits tests did not meet specifications.

ii. Based on the QC testing summary, 36% of the reported borrow pit gradation and Atterberg Limits tests did not meet the specifications.

iii. CL, SM, CH, SC, CL-ML, ML, SP-SM were classified from USCS ASTM

D2487 soil classification system. Based on the QC testing summary, 6% of the embankment/fill proctor tests soil classifications did not meet the specifications.

k) Topsoil material specification required placement within the outer face of the appropriate fill surface and was to have been 6 inches thick placed on the finished grade shown on the plan sheets. Topsoil was required to be placed where vegetative cover was scheduled.

l) To ensure proper compaction of the final lift, the raised embankment was required to be overbuilt a minimum of two (2) feet and then trimmed to the finished grade minus (-) six (6) inches on the side slopes to allow for topsoil. The overbuilt sections were to be built in five-hundred (500)-foot sections measured along the centerline of the embankment. The overbuild was not to be within four

(4) feet of any structure.

i. As per the kickoff meeting discussion and quality control document review, topsoil was not placed on the levee.

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 9

ii. Topsoil work was deleted by USIBWC due to concerns with the levee that had been constructed. USIBWC felt topsoil placement would hide problem areas as well as necessitate removal of topsoil if additional work was authorized.

iii. COR stated that USIBWC stopped UC work on the levee prior to placing topsoil or vegetating the slopes, because USIBWC was specifically concerned with soil compaction and lack of documentation of dispersive soil tests on the embankment soils.

m) Subgrade material specifications required compaction to 95% dry density of

Standard Proctor test ASTM D698 at -3% to +3% (obtain 0 to +3% if possible) optimum moisture content. The in place density tests were to have been performed at a frequency of 500 cubic yards per test (Specifications Page

01.46.00 - 7).

n) Testing reports submission: Specification 3.5 Materials Testing required that UC submit the results of all tests within twenty-four (24) hours of performance of the tests. Some of the test reports were missing in the quality control document section.

2.3 Technical Issues

A review of the technical issues regarding the construction work on the Sunland Park Levee is provided. This technical review consisted of reviewing materials provided by USIBWC. The noted Issues provide the observations and areas of concern resulting from the review. The review has depended heavily upon daily reports by Tetra Tech.

The following list provides construction related issues noted from the review of project records.

1. Dispersive soil testing

2. Blending (processing) material

3. Quality control (QC) testing

4. Compaction of material

5. Moisture requirement and maintaining moisture

6. Overbuild for compaction along edges

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 10

7. Placing topsoil and planting vegetative cover

8. Fill material for levee embankment

Table 2.1 presents an itemized issues log. Following Table 2.1, each of the itemized issues are discussed and compared to the applicable project specifications and plans. The italicized and changed print font portions are sections copied from the particular specification.

Table 2.1 Issues Log

Item Issue

1 Dispersive soil testing

2 Blending (processing material) – disc, sheepsfoot, grader

3 QC testing – Atterberg Limits tests for material after blending

4 Compaction of material – sheepsfoot, loader, etc.

5 Moisture requirement and maintaining moisture

6 Overbuild for compaction along edges

7 Placing topsoil, planting and growing vegetative cover soon after embankment complete

8 Borrow source identification and confirmation testing

Item 1. Dispersive Soil Testing

2.1 MATERIALS (35 41 00)

A. Fill Materials

(1) Impervious material shall consist of fine-grained materials of low permeability consisting of lean clay (CL). The clay material shall be rated as Grade 2 (nondispersive) in accordance with ASTM D6572 (Crumb Test) and either ND1 or ND2 as evaluated using ASTM D4647 (Pinhole Test).

Within the historic documents, two Crumb Test results were reported by R-K dated 9/28/2011 and labeled 1662+00, West of River (Collins Pit), and 06/13/12 and labeled E12-012901. The

Daily Report Number 364, 9-26-2011 by Tetra Tech mentions a Crumb Test by Archana at the

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 11 beginning of the project, but that test report has not been located, although report 364 states that UC did provide the Crumb Test report to Tetra Tech.

1.9 TESTING (01 46 00)

C. Testing Frequencies

Pinhole and Crumb tests are required for the clay embankment. Dispersive test grade and frequency of testing required as noted in Addendum No. 1, August 25, 2010 was ND1 or ND2 with One per pit and one per pit/subgrade blend for the Pinhole test and Grade 2 with One per pit and one per pit/subgrade blend for the Crumb test.

These tests should have been made and verified prior to compacting the material on the levee embankment. It is preferable to locate dispersive soils in a borrow source or along the levee alignment prior to placement in order to prevent placement of the dispersive soil within the embankment fill.

Two dispersive soil test results were located in the project documentation, and both were Crumb tests. One test dated 9-28-2011 referenced the Collins Pit, while the other test, dated 6-13-2012 has no reference to the sample location or a borrow pit.

The specified frequency for dispersive tests is not clear. One dispersive test per borrow source

(pit) would not be considered sufficient. The one test per pit and one per pit/subgrade blend would imply that if the levee subgrade was blended with borrow pit soil, then a dispersive soil test would be required for each type of subgrade soil to be blended with the borrow soil. As stated by NRCS (NEH 633.13)

“Dispersive clay often occurs as random lenses in soil profiles, and sampling must be planned accordingly. Numerous small, discrete samples are required to detect the random occurrence of dispersive clay in soil profiles, and they should be collected randomly both by area and by depth.” Page 23 of 50

NRCS further recommends that soil samples for dispersion tests must be numerous, discrete, collected at random, and at their natural water content.

In our professional opinion, insufficient number of crumb and pinhole dispersion tests were performed when compared to project specifications and NRCS guidelines.

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 12

Item 2. Processing or Blending Soils to be placed in the Levee Embankment

2.2 EQUIPMENT (35 41 00)

I. Materials Manipulation Equipment. Scarifiers, discs, spring-tooth or spike tooth harrows, spreaders, and other equipment shall be suitable for use in manipulating materials in preparation of use in construction.

Much if not all of the soils used in the levee embankment construction were blended soil types mixed proportionately to result in the specified plasticity, that being PI between 15 and 30, with

LL less than 45. Blending soils to produce a specific soil type as specified requires particular care by the equipment operators who must be familiar with soil types and the intended results.

The Tetra Tech Daily reports lists JD 772D Grader, Volvo G730B Grader, Volvo G940 Grader, as well as a tractor with disc/Case International 9150 processing material. If fill material is dumped in piles or windrows, the material may be mixed by featheredging (use of a grader) abutting layers of dissimilar soil for at least 100 feet to ensure there are no abrupt changes in soil type. While graders have been used to process soil blends, the procedure is slow, requiring extreme deliberateness by the operator to ensure the soil types mix as mentioned above. The daily reports mention processing and compacting material using Sakai Sheepsfoot Roller and

Cat 505T Sheepsfoot Roller. Tamping rollers compact but do not mix soil.

Of the soils tested on samples from within the embankment (Kenall borings), 31% of the tested soils lie outside the project specification limits. The project specifications stated that “the plasticity index shall be greater than 15 and less than 30.” It has been interpreted that the intent was 15 to 30 and the out of specified limit for PI and LL has been calculated based on 15 ≤ PI ≤

30, and LL ≤ 45.

Also, percent passing No. 200 sieve was specified as “50% passing the #200 sieve” (interpreted as at least 50% passing). Therefore, for the 31% outside of specification, if Atterberg Limits were outside the range, or if #200 was outside the specified range, it was listed as non-compliance with specification and included in the calculation to yield the 31% value. Table 2.2 summarizes the number and percentages of embankment materials tested that did not meet the specification based on Kenall laboratory testing. Figure 2.2 provides a spatial distribution of the out of specification embankment material along the east bank of the Sunland Park Levee (CE2).

Figure 2.3 provides a spatial distribution of the out of specified embankment material along the west bank of the Sunland Park Levee (CW2).

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 13

Table 2.2 Summary of Out of Specification Embankment Material (Kenall

Laboratory Data)

Levee Reach

Laboratory Tests of Embankment Material Determined to be Non- Compliant with Specification

Atterberg Limits (AL) Passing -200 Mesh

Sieve AL or -200

CE2 40 of 135 30% 30 of 237 13% 67 of 245 27%

CW2 32 of 56 57% 11 of 96 12% 41 of 108 38%

Total 72 of 191 38% 41 of 333 12% 108 of 353 31%

Figure 2.2: Distribution of Out of Specification Embankment Material - CE2

3730.0

3735.0

3740.0

3745.0

3750.0

3755.0

3760.0

3765.0

3770.0

3775.0

1500+00 1550+00 1600+00 1650+00 1700+00 1750+00 1800+00 1850+00 1900+00 1950+00

El ev at io n N

A V

D

Station

Top of Levee

CL (out of spec)

CH

CL-ML

ML

<50% Passing No. 200

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 14

Figure 2.3: Distribution of Out of Specification Embankment Material – CW2

The existence (documentation by Tetra Tech) of dry soil layers, streaking, sandy soil, and friable soil along the levee slopes can be caused by inadequate soil processing when attempting to blend sand and clay. Hydrating the soil during the process is also beneficial in breaking soil clods and achieving desired moisture content. Since the soils used to build the levee embankment were mixed (blended), the presence of sandy soil, or dry soil layers and friable soil was likely the result of not complete mixing of the soil types (clay and sand) while hydrating

(using water to help the mixing and achieving optimum moisture for compaction) at the time of placement and compaction. Notes on the Tetra Tech inspector reports regarding dry soil seams in fill appeared on Report No. 345 9-7-2011, and was re-worked as reported on 9-8-2011, Report No. 346. On 11-28-2011, Report No. 427, concern about dry levee material was noted.

The dry soil notes re-occurred on 1-3-2012, Report No. 463 and continued on the inspector reports through 11-21-2012 Report No. 786 which is the end of the project. No documentation was found that the dry soils had been re-worked.

Item 3. Quality Control Testing for Embankment Soil Classification

2.1 MATERIALS (35 41 00)

A. Fill Materials

(1) Impervious material shall consist of fine-grained materials of low permeability consisting of lean clay (CL). Impervious material shall be free of crushed rock, debris, plant growth, 3748.0

3750.0

3752.0

3754.0

3756.0

3758.0

3760.0

3762.0

3764.0

3766.0

1500+00 1550+00 1600+00 1650+00 1700+00 1750+00 1800+00 1850+00 1900+00 1950+00

El ev at io n N

A V

D

Station

Top of Levee

CL (out of spec)

CH

CL-ML

ML

<50% Passing No. 200

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 15 roots, and humus. The Plasticity Index shall be greater than 15 and less than 30. The Liquid Limit shall not exceed 45.

Numerous quality control tests are commonly needed and performed, not only to verify that the specified soil mixture has been achieved, but also to track the blending operation to prevent the soil mixture from drifting outside the specified limits. This ongoing, deliberate testing program

(QC testing) becomes the reference point for the contractor, as well as the documentation for compliance to contract specifications. It appears that the contractor had the QC firms produce numerous Moisture/Density Relationship Tests (Standard Proctor tests), and with each one of these tests, Atterberg Limits tests were performed. However, it can take up to 3 days to adequately prepare, perform, and calculate the “Proctor Tests,” while in the meantime, the soil could be placed within the embankment, compacted, and perhaps covered with another lift of soil. Specification 3.5 materials testing required submission of test results within 24 hours of performance of tests. Atterberg Limits results were reported with moisture/density tests.

The specification 01 46 00, 1.9 Testing, C. Testing Frequencies requires PI-LL testing in the clay embankment for each 5,000 cubic yards placed. For a top levee width of 16 feet, and 2.5:1 and 3:1 side slopes, a levee 8 feet in height and a soil lift thickness of 6 inches compacted, soil classification testing would be required about each 0.8 to 0.9 mile for the bottom lift. At the mid-height of the levee, or 4 feet, soil classification testing would be required about each 1.3 to 1.4 miles.

For an earthwork operation mixing soils to a specified plasticity index, verifying PI about every mile to mile and one-half is not a sufficient number of tests for quality control. Based upon

594,025 cubic yards of fill in the levee embankment for the contract (USIBWC quantity), 120 soil classification tests would be required; 187 tests were submitted and accepted as valid by

USIBWC. This amount of testing would meet the specification requirement, but information in the daily reports (Tetra Tech Report Nos. 504, 570, 577 as examples) stated that Tetra Tech would have the results “in about 1 month when they come in attached to the Contractor’s daily report.”

When considering blending soils to a specified limit as discussed in Item 2. Processing or

Blending Soils to be placed in the Levee Embankment (page 12), it appears that more QC tests during mixing of the soils to be placed in the embankment would have indicated that either blending the clay and sand differently, or different proportions would have provided the contractor data indicating out of specification prior to placement and compaction.

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Item 4. Compaction of Material

2.2 EQUIPMENT (35 41 00)

B. Towed Tamping Rollers. Towed tamping rollers shall be used for compaction of impervious material. C. Self-Propelled Tamping Rollers. Self-propelled tamping rollers may be used in lieu of towed tamping rollers provided the foot pressure on the tamping feet of the self-propelled roller are approximately the same as the foot pressure on the towed roller.

Cohesive soils require a kneading action, and a “bottom up” compactive effort; therefore, the use of tamping rollers as specified is important for compacting the clay levee embankment. It appears that nearly all the compaction was performed with tamping rollers. There was mention in Report Numbers 735 and 736 that the Dynapac Pneumatic Roller was being used to compact, but that compaction may have been a granular material and not the clay embankment.

Report Numbers 617 through 627 documented “Loading Dumps/Compacting material” by a

Volvo L120F Loader, which is not a tamping roller and therefore not according to specification. If compaction equipment within the embankment consisted of anything but the tamping rollers, then seams between layers are more likely and if the processing has not completely blended hydrated soils, then the dry pockets or seams noted in the inspector’s reports could occur.

Also in the Tetra Tech Daily Report Number 617, under verbal communication with contractor, the inspector noted, “Because they are using a loader to wheel roll embankment on CW2 I asked that they make an effort to compact the entire width no[t] missing the space between the tires on the loader.” As previously stated, compaction of the clay soil requires kneading and bottom up compaction. If complete soil blending and hydration was not thoroughly accomplished, compacting with rubber tired roller (front end loader), layering, dry pockets or seams, and non-uniform compaction would be exacerbated. Compaction with loaders does not seem to be widespread or common within the project, but even minor areas could produce problematic sections within the compacted levee embankment.

Item 5. Moisture Requirement and Maintaining Moisture

3.4 FILL OPERATIONS (35 41 00)

D. Minimum Density and Moisture. Surfaces subjected to fill to include prepared ground surface and the previous placed lift shall be moisture-conditioned by scarifying to a minimum depth of six

(6) inches and re-compacted to a minimum of ninety-five percent (95%) of the maximum dry density as determined from ASTM D 698. Scarified surfaces compacted prior to placement of the subsequent lift shall be re-scarified. The moisture content of the subgrade and select fill shall be maintained within the

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 17 range of optimum moisture content to two (2) percentage points above the optimum moisture content until permanently covered. (This is the requirement published in the project specifications.)

The specification section 1.9 Testing, C. Testing Frequencies (Table in specifications section

01.46.00 page 7) states that the moisture content of the clay embankment is to be 95%

Maximum Dry Density (ASTM D 698) with moisture content of 0% to +3% Optimum Moisture

Content. The moisture content requirements presented in the Notes on the S&B Infrastructure plans also refer to the 0% to +3% moisture content range.

Observing the QC test reports, it appears that Archana referred to the 0% to +2% range, while

R-K and Tetra Tech were observing the 0% to +3% moisture range. The referral to the 0% to

+3% as presented on the plans would be acceptable and not harmful to the levee embankment.

Item 6. Overbuild for Compaction Along Edges

3.4 FILL OPERATIONS (35 41 00)

Q. Expanding Existing Levee Slopes. To ensure proper compaction of the final lift, the raised embankment is to be overbuilt a minimum of two (2) feet and then trimmed to the finished grade minus (-) six (6) inches on the side slopes to allow for topsoil. The overbuilding shall occur in five hundred (500) feet sections measured along the centerline of the embankment. After the completion of five hundred (500) feet of overbuild, the embankment will be trimmed to finished grade minus (-) six (6) inches or as shown on the plans. The overbuild will not be placed within four (4) feet of any structure.

The inclusion of the overbuild as specified is important in order to provide sufficient lateral support and horizontal soil layer surface upon which the compaction equipment can apply full compactive effort to the sides of the levee. Tetra Tech mentioned in numerous daily reports concern about “visually loose at the surface” for both CE2 and CW2, and referred to this as an

“ongoing issue.”

Tetra Tech Daily Report Number 427 (11-28-2011) has a discussion under the PROGRESS section where the inspector raises concern about side slopes “that are hard and shiney,” and other sections that are “fryable” in appearance.” The report mentions that after a grader dug down, some of the material looked good, and other locations had 8 inches of dry material at the top. This area was to be reworked. This was the first mention of dry material on the levee slopes.

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In Report Number 463 (1-3-2012), under the remarks section, the inspector wrote, “On CE2 UC is strictly using material excavated from the existing levee for embankment. Due to the excavation requirements approximately 2 feet of the sand layer under the existing clay layer is being removed and mixed in as it is stock piled. No outside source for clay is being added.

Based on test results the stock piled blended material is meeting specification for both PI and gradation. Based on visual observation previously placed embankment is becoming dry and friable. It is Tetra Tech’s position that the addition of sand to the existing clay layer will only increase the friability of the embankment.”

On 1-4-2012, Tetra Tech Daily Report Number 464 repeated within the REMARKS section the above quotation. From that time on, the Daily Reports included some mention of the concern with comments about embankment being “dry and friable,” and concerns about “sand content.”

These comments continued to the end of the project.

Item 7. Placing Topsoil

Topsoil is defined in specification PART 2.1 C Topsoil Material. Topsoil is further mentioned in (35 41

003).

4 FILL OPERATIONS

Q. Expanding Existing Levee Slopes. To ensure proper compaction of the final lift, the raised embankment is to be overbuilt a minimum of two (2) feet and then trimmed to the finished grade minus (-) six (6) inches on the side slopes to allow for topsoil.

From these requirements, as well as from standard earthwork operations, it can be seen that the levee overbuild, compaction, moisture control, trimming and topsoil placement are construction steps dependent upon proper completion of the previous step. Moisture content was to be maintained “until permanently covered” per Specification 3.4 D. Although no comments about moisture control or placement of topsoil were found within the project documents and daily reports, we understand from USIBWC that the contractor was instructed not to place topsoil since USIBWC was concerned about the embankment and did not want the embankment soils covered which would prevent direct visual observation.

The specification 31 92 00 vegetation for erosion control presents Materials and Equipment, Construction Methods, and Payment, and requires a 120 calendar day maintenance by the

Contractor for permanent seeding, which was not completed as directed by USIBWC.

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Item 8. Fill Material

1.6 SOURCES OF FILL MATERIAL (35 41 00)

A. Material Source Usage. A detailed Plan of Operations shall be submitted for COR review and compliance-confirmation addressing all aspects of material sources to include borrow operations.

B. Material Sources Proposed by the Contractor. The Contractor shall submit for review and compliance-confirmation to the COR all material sources. The COR will make the final determination on compliance-confirmation of alternate sources.

Design plans and specifications often include borrow material sources that have been verified for soil type and quantity. Quality control testing by the contractor for material verification during construction would be implemented to confirm that specified soil types are placed in the embankment as per the plans and specifications. The specifications for Sunland Park Levee placed the responsibility of locating fill material of the correct soil type upon the contractor, with the “final determination” of the material source on the COR. The specifications as written place the responsibility for the fill material and compliance with soil types upon the contractor. The above referenced specifications required “COR review and compliance-confirmation.” With the

COR having final determination, it is not clear if the approval indicated contractor compliance, even though material sources had not been tested for dispersive clay. Even with COR approval and compliance-confirmation of the borrow source, it is our professional opinion that such confirmation by USIBWC did not relieve the contractor from providing fill material that met the project specifications.

Summary of Technical Issues

In summary, the technical issues presented convey the observations resulting from the detailed review of the design and construction documentation as provided by USIBWC for this Forensic

Engineering Analysis. Two of the eight issues discussed are considered significant and present risks to the levee embankment and protected areas during high water events.

The two main issues that remain as items of concern include

1. Site representative’s comments (Tetra Tech) noting dry soil layers or pockets within the levee that were not corrected, and

2. The presence of dispersive soil within the levee embankment does not comply with the project Technical Specifications or with FEMA 65.10 requirements.

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The presence of dry soil layers or seams within the embankment could be associated with silt or sand and can result in increased rates of levee erosion during flood events. The dry or silty and sandy soil layers may not be of sufficient quantity or extend through the levee to result in drastically increased embankment erosion. Therefore, this issue is considered to be a concern, but not as critical as the dispersive soil issue.

These two issues do not meet the project specifications, and would also be considered non-compliant with FEMA §65.10 (b) Design criteria (3) Embankment Protection and (4)

Embankment and Foundation Stability regarding “no appreciable erosion of the levee embankment can be expected during the base flood… and seepage into or through the levee foundation and embankment will not jeopardize embankment or foundation stability.” These items are further explored and discussed in the following sections including test data for soil types and dispersive soils.

2.4 Meteorological Data

Santa Teresa Airport Air Station through National Centers for Environmental Information

National Oceanic and Atmospheric Administration website has been used for the collection of weather data. This weather data is being used for quantifying and profiling weather related-risks for the Sunland Park Levees CE2 and CW2, particularly during and since construction. The weather data is shown in the Table 2.3. The data collected in reference to this project is from year 2006 to December 2015.

Table 2.3: Weather Events – Santa Teresa Airport Weather Station National Climatic Data

Center (NCDC) Data

Year WT11 PRCP (tenths of inches) TMAX (F) TMIN (F)

2006 0 146.14 77.99 49.07

2007 0 111.61 77.31 48.61

2008 0 148.98 77.01 47.03

2009 0 99.88 78.19 47.99

2010 0 104.76 77.49 47.62

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Table 2.3 Continued..

Year WT11 PRCP (tenths of inches) TMAX (F) TMIN (F)

2011 0 39.76 78.90 47.70

2012 0 40.08 79.42 48.87

2013 0 111.97 76.51 48.16

2014 0 93.50 77.94 49.60

2015 1 125.20 77.36 49.92

Note:

WT07 - Dust, volcanic ash, blowing dust, blowing sand, or blowing obstruction

WT11 - High or damaging winds

WT10 - Tornado, waterspout, or funnel cloud

WT14 - Drizzle

WT16 - Rain (may include freezing rain, drizzle, and freezing drizzle)

PRCP - Precipitation (tenths of inches)

TMAX - Average Maximum temperature (degrees F)

TMIN - Average Minimum temperature (degrees F)

3 DATA COLLECTED

3.1 Photo Documentation and Field Visit

Kenall team members visited the project site on April 1 and 2. Other levees within driving distance were also visited (Canutillo Levee reaches CE1 and CW1 and Mesilla Levee reaches

ME2 and MW2).

Team Kenall completed a site walk through the Sunland Park Levees CE2 and CW2 segments.

Photo documentation of the existing levee was performed during site walk throughout the levee.

Photographs have been used to document general conditions and provide a visual of the levees. Field photograph documentation (USIBWC Form 148) of the site conditions was completed on April 24, 2015 and is included in Appendix A.

a) Erosion holes and rivulets were observed along the levee, and portions of the levee slope erosion rivulets were of up to 26 inches deep.

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b) Photograph documentation of site conditions was performed from April 1, 2015 through April 24, 2015. Nearly 5,200 photographs were captured to document field conditions.

c) All sections of the Sunland Park Levee within the limits of work were carefully observed by members of Kenall on April 1 and April 2, 2015. We expected to find intermittent sections of distressed levee within problem-free reaches. If this were the case, our sampling and testing program may have shown a clear soil behavior distinction and point directly to the source of the problem. Instead, we observed rill and erosion throughout the limits of work, with little vegetation on the levee slopes

(see photos below).

Picture 3.1. Detail of Erosion Rill Picture 3.2. Erosion Rills on the Riverside Slope

4 INTERVIEWS

Discussions with USIBWC occurred during the project kickoff meeting held on April 1, 2015 at the USIBWC Headquarters in El Paso, Texas. The following items were discussed during the meeting, based upon questions raised by the contracting team.

1. The R-K report dated December 2008, indicated severe cracking and rutting along the top of levee. USIBWC personnel explained that this data and report references levee construction by USIBWC work forces, and preceded the levee design by S&B and subsequent construction by UC which commenced in 2010.

2. At the conclusion of construction by UC, outstanding issues with compaction, compaction test results, and completion of the QC testing for the levee

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 23 embankments remained unresolved. UC was the general contractor, with

Archana and R-K providing quality control testing of the construction work.

USIBWC retained Tetra Tech to be the owner’s representative on site and to provide construction management services. The specifications stated that

USIBWC would not provide confirmation QA testing (SPECIFICATION 35 41

00 CONSTRUCTION OF LEVEE, PART 3-CONSTRUCTION METHODS, 3.5

MATERIALS TESTING).

3. USIBWC stated there were numerous field density tests that were outside the specified limits, and many of these tests were not re-tested for confirmation of additional compaction or moisture adjustment.

4. USIBWC stopped work on the levee by the contractor prior to placing topsoil or vegetating the slopes since USIBWC was concerned with soil compaction and no documentation of dispersive soil tests on the embankment soils.

5. Several borrow pits were used by the contractor for levee fill.

5 FIELD INVESTIGATION

5.1 General

The objective of the field investigation was to determine the properties of soils used in the embankment construction, construction quality, voids and sinkholes. Field investigation was performed in two stages and mentioned below.

Geophysical Investigation.

Geotechnical Investigation.

5.2 Geophysical Investigation

Geophysical investigations are used to obtain general information about a project site such as geologic materials, location of the water table, buried items, and sink holes. A geophysical field investigation was performed in two stages as described below. The geophysical investigation survey was performed based on the ASTM D6429. Pursuant to Table 1 of ASTM D6429, concerning the selection of geophysical methods for common applications like forensics, voids and sinkholes, and soil and rock properties, ground penetrating radar (GPR) was chosen to be the primary method and Frequency Domain Electromagnetic (FDEM) was chosen as the alternate or secondary method.

Kenall Project No. 1929 / Contract No. IBM15C0002 Page 24

During the preliminary oversight of the project, GPR survey was chosen as the primary method.

However, given the length of time that ground penetrating takes to survey 11.83 miles of levee and the safety measures needed to safely conduct the survey on slope of the levee, Kenall chose to use a combination of FDEM and GPR survey methods.

Electromagnetic Survey (EM 31 Survey).

Ground Penetrating Radar Survey (GPR Survey).

5.2.1 Electromagnetic Survey

EM 31 Survey is used to measure the apparent electrical conductivity of subsurface materials.

Electrical conductivity measures the degree to which the soil conducts an electrical current and can be used to infer geologic materials, the location of the water table and detect buried items.

The Electromagnetic Mapping (EM) survey was started on April 16, 2015 and completed May

21, 2015. A cautious approach was adopted on the riverside slope, since some riverside sections of the slopes contain erosion rivulets. The EM Survey mapbook is attached in

Appendix D.

Analysis was performed on the EM31 Survey results. This revealed 198 spots with apparent high conductivities. These are tabulated in Appendix D.

Generally, measurement of higher apparent conductivities implies a thicker soil cover, while measurement of lower apparent conductivities suggests a greater effect from bedrock, therefore indicating a thinner soil cover. Discrete areas of elevated conductivity within a limited area can be an indicator of subsurface sinkhole development activity.

5.2.2 Ground Penetrating Radar Survey

GPR Survey is a geophysical instrument that transmits high frequency electromagnetic (EM) pulses into the subsurface. The transmitted EM pulses respond to changes in materials with sufficiently different electrical properties such as those caused by mineral content, salinity, water content, density, voids, etc. GPR Survey is performed after both photo documentation and the

EM 31 survey in order to get a more detailed description of voids and density. We performed

Ground Penetrating Radar (GPR) survey services from August 18 through August 24, 2015.

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GPR Survey results are correlated with the existing geotechnical soil borings. Also, five additional soil borings were drilled up to a depth of 15 feet to provide ground truthing and to correlate with the EM Survey and GPR Survey results. The five additional soil boring coordinates are summarized in the Table 5.1.

Table 5.1 Soil…