REDUCED Geotech Donna Pump to Brownsville Raba Kistner.pdf

GEOTECHNICAL EXPLORATION AND ENGINEERING EVALUATION OF

LEVEE SYSTEM

FOR

THE LOWER RIO GRANDE FLOOD CONTROL PROJECT

FROM CAMERON COUNTY LINE OF DONNA PUMP TO BROWNSVILLE

LEVEE REACH TO ITS EASTMOST LIMIT

Ra.ba-Kistner

Project No. AMA08-115-00 July 24, 2009

Engineering• Testing • Environmental• Facilities• Infrastructure

l. ◄ Raba Kistner

RabaNKistner Consultants, Inc.

800 E. Hackberry McAllen, Texas 78501

(956) 682-5332 • FAX (956) 682-5487

www.rkci.com

Ms. Sharlotte L. Teague, P.E., Deputy Project Manager S&B Infrastructure, Ltd.

5408 North 10 th Street

McAllen, Texas 78504

RE: Geotechnical Exploration and Engineering Evaluation of Levee System Final Technical Memorandum The Lower Rio Grande Flood Control Project - From Cameron County Line of Donna Pump to Brownsville Levee Reach to its Eastmost Limit USIBWC Task No. IBM08T0036 S&B Project No. U0450.405

Dear Ms. Teague:

Raba-Kistner Consultants, Inc. (R-K) is pleased to submit our Final Technical Memorandum for the geotechnical explorations and engineering evaluation of the levee system for The Lower Rio Grande Flood Control Project. This memorandum specifically addresses the levee segment from the Cameron County line of Donna Pump to the Brownsville Levee Reach to its Eastmost limit. These services were performed in accordance with the executed Subcontract for Consultant Services between S&B Infrastructure, Ltd. (CLIENT) and R-K for the above referenced indefinite delivery - indefinite quantity contract (IDIQ) with the United States International Boundary and Water Commission (USIBWC). Written notice to proceed was received by our office via facsimile transmittal on October 1, 2008.

The purpose of this study was to drill borings along the existing alignment of the levee, to perform laboratory testing to classify and characterize subsurface conditions, and to prepare a technical memorandum presenting our geotechnical analyses of the levee in general accordance with the U.S. Army Corps of Engineers (USACE) document Engineering Manual (EM) 1110-2-1913 Design and Construction of Levees and the Federal Emergency Management Agency (FEMA) Requirements for Mapping Levees (44 CFR 65.10) as they pertain to geotechnical evaluations.

/\ustin • Ui-owni;v1llc • H F'nso o Houston o IJc/\llen ° Mexico O Sari ,:1ntonio

We appreciate the opportunity to be of service on this project, and look foiward to working with you throughout the remaining phases. If you have any questions, please call.

Very truly yours, RAB.l\:K)STNER CONSULTANTS, INC.

/ b--f? I '"' Rus . Thomas,DP.E.

Seni eject Manager

�-6·-·-

Chris L. Schultz, P.E.

Senior Vice President

RL T/JAF/CLS/KM/ns/mem

Attachments

Copies Submitted: Above (4)

Raba-KistJITterc

GEOTECHNICAL EXPLORATION AND ENGINEERING EVALUATION OF LEVEE SYSTEM

THE LOWER RIO GRANDE FLOOD CONTROL PROJECT

FROM CAMERON COUNTY LINE OF DONNA PUMP TO

BROWNSVILLE LEVEE REACH TO ITS EASTMOST LIMIT

CAMERON COUNTY, TEXAS

USIBWC TASK NO. IBM08T0036

FINAL TECHNICAL MEMORANDUM

for

U.S. SECTION OF THE INTERNATIONAL BOUNDARY AND WATER COMMISSION

(USIBWC)

Prepared for

S&B INFRASTRUCTURE, LTD.

McAllen, Texas

Prepared by

RABA-KISTNER CONSULTANTS, INC.

McAllen, Texas

PROJECT NO. AMA0B-115-00

Raba-Kistner

Project No. AMA0S-115-00

EXECUTIVE SUMMARY

The purpose of this study was to drill borings along the existing alignment of the Donna Pump to the Brownsville Levee Reach to the eastern limit of The Lower Rio Grande Flood Control Project levee system, to perform laboratory testing to classify and characterize subsurface conditions, and to prepare a technical memorandum presenting our geotechnical analyses of the levee in general accordance with the U.S. Army Corps of Engineers (USACE) document EM 1110-2- 1913 Design and Construction of Levees and Federal Emergency Management Agency (FEMA) Requirements for Mapping Levees (44 CFR 65.10) as it pertains to geotechnical evaluations and to provide geotechnical engineering design recommendations with engineering solutions for the levee against the provided 100 year flood water surface elevations.

Subsurface conditions along The Lower Rio Grande Flood Control Project were evaluated by drilling 300 borings to a maximum depth of about 50 feet below the existing top of levee using truck-mounted drilling rigs. The borings were advanced using straight flight augers in combination with mud rotary drilling techniques and were backfilled with cement-grout following completion of each day's drilling operations.

The subsurface conditions observed in the borings performed for this study were relatively consistent along the entire length of levee. In general, fill materials associated with the existing levee were observed overlying naturally deposited soils common to the area. These fill soils were observed at thicknesses ranging from about 1 to 18 feet. The vast majority of the fill materials observed in the borings performed for this study consisted of lean clays (CL). The remaining the fill materials were comprised of fat clays (CH), sands (SP and SP-SM), and silts

(ML).

Areas where sand and/or silt layers were observed within the existing fill soils are of particular concern. Non-cohesive soils have a much higher hydraulic conductivity than cohesive soils, which will allow water to flow through the earthen levee at higher rates within these non cohesive layers than through cohesive soil layers. When observed, these sand and silt layers were about 2 to 4 feet in thickness.

Beneath the fill soils, naturally deposited cohesive soils with interbedded layers of sands and silts were observed. The naturally deposited soils vary over the length of the levee project in both depth and thickness. The native soils encountered in the borings conducted for this study were predominately comprised of cohesive soils, consisting of lean clays (CL) and fat clays (CH). Encountered in lesser extend were sandy fat clays and sandy lean clays. The amount of fat clays observed in the naturally deposited soils is significantly higher than that observed in the fill soils, where lean clays predominated. The native non-cohesive soils observed in our borings were predominately silty sands (SM), sands with silt (SP-SM), clayey sands (SC), sands (SP), sandy silts (ML), silts (ML), and clayey silts (ML).

A detailed description of the soil conditions observed at each boring location has been presented in the Boring Logs, Figures A-2 through A-301, of Appendix A. The lines designating the interfaces between strata on the boring logs represent approximate boundaries. Transitions between strata may be gradual.

Project No. AMA0B-115-00

The existing and modified levees should meet three important criteria: they should be resistant to the forces of erosion, should exhibit a suitable allowable factor of safety with respect to slope stability, and have an acceptable factor of safety against instability due to through- or under seepage. The levee structure must meet these criteria so that the calculated risk of failure is consistent with criteria established by the USACE guidelines.

Portions of the existing levee will be raised and side slopes reconstructed to a 3: 1 slope or flatter. If silts are observed on the river side of the levee, the silts should either be partially replaced with properly compacted clay fill sols or plated with at least 3 feet of properly compacted fill soils.

Underseepage is a major concern for a significant portion of the alignment. Based on the conditions observed in the soil borings drilled for this project, it appears that about one-eighth of the levee alignment may be at risk for this failure mode. After reviewing the soil profiles in the project borings along with the existing and proposed levee cross-sections, it appears that land side toe drains will provide adequate seepage control. This approach will result in a significant cost savings when compared to a full penetration cutoff wall or relief wells. A typical toe drain detail is presented on Figure 11 of the Appendix C.

This Executive Summary is intended for information purposes only, and should not be utilized separately from the entire Final Technical Memorandum. The following technical memorandum contains a more definitive explanation of the study performed and the results of our field and laboratory tests. In addition, the technical memorandum contains a greater discussion on failure mechanisms, the methods and results of our analyses, and our design considerations.

TABLE OF CONTENTS

INTRODUCTION

PROJECT BACKGROUND

PROJECT DESCRIPTION

RISK

LIMITATIONS

FIELD EXPLORATION

LABORATORY TESTING

STRENGTH TESTS

CONSOLIDATION TESTS

HYDRAULIC CONDUCTIVITY (PERMEABILITY) TESTS

GENERAL SITE CONDITIONS

SITE DESCRIPTION

SITE GEOLOGY

SEISMIC COEFFICIENTS

STRATIGRAPHY

IMPACT OF SAMPLING AND TESTING PROCEDURES ON

MEASURED AND DESIGN SOIL PROPERTIES

PERMEABILITY

INFERRED PERMEABILITY

DEPTH-TO-WATER

EARTHEN LEVEE SYSTEM

DESIGN CONSIDERATIONS

Probable Failure Modes

SLOPE STABILITY

Minimum Factor of Safety Slope Configurations Method of Analysis Loading Conditions

SOIL PARAMETERS

Results of Analyses

TABLE OF CONTENTS

ii

SEEPAGE ANAL YSIS

Drainage layer Seepage barrier Relief wells Other approaches

SETTLEMENT .... :

SOIL PARAMETERS

Results of Analyses

TRAFFICABILITY

CONCLUSIONS

RECOMMENDATIONS

EARTHEN LEVEE SYSTEM

CONSTRUCTION RECOMMENDATIONS

GENERAL CONSTRUCTION CONSIDERATIONS

VEGETATIVE COVER FOR CLAY-PLATED LEVEES

CRUSHED LIMESTONE BASE

TABLE OF CONTENTS

ATTACHMENTS

Appendix A (Field Testing Summary) iii

Boring Location Map ........................................................................................ A-1a through A-1s Logs of Borings ................................................................................................ A-2 through A-301 Key to Terms and Symbols ................................................................................................. A-302 Results of Soil Sample Analyses ..................................................... A-303a through A-303wwww

Appendix B (Laboratory Testing Summary) Grain Size Curves ............................................................................................ B-1 through 8-126 Unconfined Compression Test Reports ....................................................... 8-127 through 8-172 Consolidated Undrained (CU) Triaxial Compression Test Reports .............. 8-173 through 8-214 Consolidated Drained (CD) Triaxial Compression Test Reports .................. 8-215 through 8-227 Direct Shear Test Reports ........................................................................... B-228 through B-258 Hydraulic Conductivity (Permeability) Test Reports ..................................... B-259 through B-299 One-Dimensional Consolidation Test Reports ............................................. 8-300 through B-341 Moisture-Density Relationships (Proctor) ..................................................... 8-342 through 8-365 Crumb Tests ...................................................................................................... 8-366 and 8-367 Additional Hydraulic Conductivity (Permeability) Test Reports ..................... B-368 through B-394

Appendix C (Results of Geotechnical Analyses) Slope Stability and Seepage Analysis ............................................................... C-1 through C-10 Typical Detail Toe Drain ........................................................................................................ C-11

Raba.-Kistner

INTRODUCTION

Raba-Kistner Consultants, Inc., (R-K), has completed the authorized subsurface exploration and engineering analyses for the proposed rehabilitation improvements to the Donna Pump to Brownsville Levee Reach of the Lower Rio Grande Flood Control Project (LRGFCP) of the U.S.

Section of the International Boundary and Water Commission (USIBWC) in Cameron County, Texas. This technical memorandum briefly describes the procedures utilized during this study and presents our findings along with our geotechnical analyses of the levee, which was performed in general accordance with the USACE document EM 1110-2-1913 Design and Construction of Levees and FEMA Requirements for Mapping Levees (44 CFR 65.10) as it pertains to geotechnical evaluations.

PROJECT BACKGROUND

We understand that the USIBWC has recently conducted studies to assess the ability of the United States levees of the LRGFCP to safely contain flood flows in the Rio Grande. The LRGFCP extends from the Town of Penitas, Texas, at its upstream end, to 28 miles above the Gulf of Mexico, a distance of about 158 river miles. The LRGFCP has two diversion dams, Anzalduas Dam and Retamal Dam, approximately 17 and 57 river miles below Penitas, which divert portions of the flood flows into the Main Floodway and the Mexican Floodway, respectively.

The LRGFCP was constructed to provide flood protection to urban, suburban, and irrigated lands in the Rio Grande delta in both the United States and Mexico. Each country designed and constructed the portion of the project located in its territory.

PROJECT DESCRIPTION

One of the reaches of the LRGFCP levees that was found to be in need of rehabilitation improvements was that labeled as the Donna Pump to Brownsville Levee System. The Donna Pump to Brownsville levee reach is approximately 64.5 miles, with 48.5 miles located within Cameron County and 16 miles located within Hidalgo County, Texas. This study pertains to the entire Cameron County portion of the Donna Pump to Brownsville levee reach, as well as a small portion (approximately 2.5 miles) of the Hidalgo County portion, just west of the Cameron County line, for a total 51 miles.

The USIBWC studies indicate that the existing levee in this reach is deficient in height from 1 to 3 feet. The proposed rehabilitation improvements consist of raising the top of levee elevation by the addition of earthen fill. The top elevation of these improvements will be as required to provide containment of design flood flows with a freeboard of 3 feet.

The scope of our study for the proposed rehabilitation improvements consists of performing a geotechnical investigation for the design of the proposed improvements along the existing levee alignment, including slope stability, levee settlement, slope stability evaluations, and seepage analyses.

RISK

The geotechnical engineering design recommendations contained in this memorandum are intended to provide S&B Infrastructure, Inc. and the U.S. Boundary and Water Commission with design information. We have attempted to provide guidance regarding the impact of various design choices on calculated factors of safety with respect to calculated slope stability. The design factors of safety used for this study were taken from USAGE EM 1110-2-1913 dated April 30, 2000. The selection of a given design factor of safety implicitly includes a decision regarding the level of acceptable risk for a project. This study did not include an independent evaluation of risk with respect to levee performance, and adopted the published USAGE design factors of safety as the current performance standards for these types of structures. Levees are only designed to provide protection to a certain flood level; R-K did not determine the chosen design flood level, and the selection of this parameter is outside our area of expertise.

We understand that USIBWC used the computer program FLO-2D to evaluate the water surface profile for the 100-year design flood in accordance with the current FEMA Levee Certification criteria. Furthermore, for the purposes of this memorandum, it has been assumed that the maximum time that the levee would be subjected to the design flood level is 7 days.

It is important to note that the levee systems are being designed to perform a required function (retain flood waters) under stated conditions (during a 100-year flood event) for a specified period of time (presently unknown.) The design may not be adequate for a different storm event or longer performance period, and unexpected damage to the levees may result in the need for repairs to the levee and/or levee improvements over time. Our conceptual design recommendations inherently assume that the levee will be properly maintained and regularly inspected by trained and qualified personnel. Our conceptual design recommendations also assume that any identified repairs will be made promptly, and the adequacy of the levee system will be regularly assessed, fully taking into account changes in weather, land use and evolving design and performance standards, with changes made as appropriate.

The geotechnical properties of the soils encountered in this study involve significant variability.

This variability includes some spatial variability; however, the spatial variability appears to occur over relatively short distances. It is important to note that levees differ from other types of structures, such as drilled piers or driven piles, in that the performance of the levee involves local, not average, soil conditions.1 The selection of design parameters for this project was based on a review of the available geotechnical data, our knowledge of the project area, design calculations using idealized geometries. The results of our analyses were then reviewed with respect to important trends and general design concepts, keeping these conditions and limitations in mind. Our conceptual recommendations are based on a conservative approach to design as is warranted for all levee structures. We believe that the combination of observed conditions and probable failure modes justifies this approach.

LIMITATIONS

This Final Technical Memorandum has been prepared in accordance with accepted Geotechnical Engineering practices in the region of South Texas for the use of S&B Infrastructure, Ltd. (CLIENT) and its representatives for design purposes. This memorandum may not contain sufficient information for purposes of other parties or other uses.

The recommendations submitted in this memorandum are based on the data obtained from 300 borings drilled along the alignment, our understanding of the project information provided to us, 1 Focht, J.A. Jr. and Focht, J.A. Ill, "Factor of Safety and Reliability in Geotechnical Engineering, Discussion and Closure", ASCE JGGE Vol. 127 No. 8, pp.700-721, August 2001.

and the assumptions with regard to water elevations and durations that are discussed in greater detail in the following memorandum. If the project information described in this memorandum is incorrect, is altered, or if new information is available, we should be retained to review and modify our recommendations.

This memorandum may not reflect the actual variations of the subsurface conditions across the site. This is particularly true with regard to existing groundwater levels that are likely to be highly variable based on precipitation events and the percent of sands versus fine grained materials. The nature and extent of variations along the levee may not become evident until construction commences. The construction process itself may also alter subsurface conditions.

If variations appear evident at the time of construction, it may be necessary to reevaluate our recommendations after performing on-site observations and tests to establish the engineering impact of the variations.

The scope of our current study does not include an environmental assessment of the air, soil, rock, or water conditions either on or adjacent to the site. No environmental opinions are presented in this memorandum.

If final added heights along the levee are significantly different from those provided by S&B Infrastructure (more than plus or minus 12-inches), our office should be informed about these changes. If needed and/or if desired, we will reexamine our analyses and make supplemental recommendations.

FIELD EXPLORATION

Subsurface conditions along the subject site were evaluated by 300 borings (designated as "DP-") drilled from October 14, 2008 through December 19, 2008, and January 15, 2009 through January 23, 2009, at the locations shown on the Boring Location Map, Figure A-1. Please note that drilling operations for the majority of the borings were terminated on December 19, 2008, and restarted when approval for the remaining borings was received by our office on Tuesday, January 13, 2009.

The boring locations shown on the Boring Location Map are approximate and are based on our review of an undated site plan titled "Lower Rio Grande Flood Control Project Donna Pump to Brownsville Levee", provided to us by the CLIENT via electronic-mail attachments on October 8, 2008, November 13, 2008, and January 14, 2009. The borings were drilled to a depth of about 50 feet each below the existing top of levee using truck-mounted drill rigs, with the borings located near the centerline of the levee cross-section to a depth equal to twice the expected final levee height. This depth of exploration is consistent with the USAGE EM 1110-2-1913 Design and

Construction of Levees. The borings were advanced using straight flight augers in combination with mud rotary drilling techniques and were backfilled with cement-grout following completion of each day's drilling operations. During drilling operations, the samples shown on the following table were collected:

Tvoe of Samole

Split-Spoon (with Standard Penetration Test, SPT)

Shelby Tubes

Grab Samples

Bulk Samples for Proctor

Number Collected

The SPT and Shelby tube samples were performed in accordance with accepted standard practices. Selected portions of the samples were sealed in containers to reduce moisture loss, labeled, packaged, and transported to our laboratory for subsequent testing and classification.

LABORATORY TESTING

In the laboratory, each sample was evaluated and visually classified by a member of our Geotechnical Engineering staff in general accordance with the Unified Soil Classification System (USCS). The geotechnical engineering properties of the strata were evaluated by the laboratory tests tabulated in the following table:

Type of Test Number Complete

Pocket Penetrometer 1688

Natural Moisture Content 2064

Atterberg Limits 1222

Percent Passina a No. 200 Sieve 1203

Grain Size Curves /Particle Size, Part I) 630

Hvdrometer (Particle Size, Part 11) 53

Specific Gravity 18

Unconfined Compressive Strenoth 71

Drv Unit Weiaht 344

Consolidated-Undrained (CU) Triaxial 42

Consolidated-Drained (CD) Triaxial 13

Direct Shear /DS) 31

One-Dimensional Consolidation 41

Hydraulic Conductivity (Permeability) 40

Moisture-Density Relationship (Proctor) 24

Crumb Tests 57

With the exception of the laboratory grain size curves (particle size, Part I), hydrometer (particle size, Part II) tests, specific gravities, hydraulic conductivity (permeability) tests, direct shear tests, one-dimensional consolidation tests, CU triaxial tests, CD triaxial tests, moisture-density relationship (Proctor) tests, and crumb tests, the results of the field and laboratory tests are presented in graphical or numerical form on the boring logs illustrated on Figures A-2 through

A-301. A key to the classification of terms and symbols used on the logs is presented on Figure A-302. The results of the laboratory and field testing are also tabulated on Figures A-303a through A-303wwww for ease of reference.

SPT results are noted as "blows per feet" on the boring logs and on Figures A-303a through A-303wwww, where "blows per foot" refers to the number of blows required for a falling 140-pound hammer to penetrate 12 inches into the subsurface materials. Where hard and/or very dense materials were encountered, the tests were terminated at 50 blows even if one foot of penetration had not been achieved.

Samples will be retained in our laboratory for 30 days after submittal of this memorandum.

Other arrangements may be provided at the written request of the CLIENT.

STRENGTH TESTS

Shear strength parameters of selected samples were evaluated by several methods. Field tests for measuring these parameters included pocket penetrometer, hand-held Torvane, and standard penetration testing. Laboratory tests for measuring these parameters included unconfined compression, multi-stage consolidated undrained (CU) triaxial compression with pore pressure measurements, multi-stage consolidated drained (CD) triaxial compression, and single-stage direct shear (OS).

Results of the field tests as well as the unconfined compression tests are presented in both graphical and numerical form in both Appendix A (on the boring logs and the Results of Soil Sample Analyses) and Appendix B (where the stress-strain behavior of each unconfined compression test is presented). Results of the laboratory strength tests are presented in the following tables. Detailed summary sheets are presented both graphically and numerically in Appendix B for each test.

Multi-stage CU tests were used to determine both total and effective soil strength parameters.

During CU testing, each stage was subjected to an effective consolidation pressure of about 1, 2, and 3 times the in-situ confining stress. When combined with the consolidation test results (discussed below) a SHANSEP-type data reduction was performed to determine appropriate soil strength parameters for modeling the planned slope improvements for this study.

The following table presents the results of our multi-stage CU tests.

Multi-Staae CU Test Results

DP-8 8 1.6757 5.7

DP-8 8 2.2659 4. 7

DP-8 8 4.4595 13.1

DP-10 15 3.1633 7.1

DP-10 15 5.6702 7.6

. > i. Effective ... · · .. ·• · ... ·. Total. > i Effecti\le > Fri¢tipp Coh,;;sion, .J=ri9\lp1J c�hesion ;q<msolidaticm J\ngle,I .· .. c:'. f\ngle,¥ <i C : 1 lress�re

(JElg > ksf deg . \ ksf .. > ksf •.... ·.

20.9 0.46 14.2 0.51 0.74

20.9 0.46 14.2 0.51 1.47

20.9 0.46

27.9 0.40

27.9

Raba-K.istner

14.2 0.51 2.84

22.5 0.25 1.98

22.5 0.25 4.02

1•,•>·•••·< I Boring

No ...

DP-10

DP-34

DP-34

DP-34

DP-42

DP-42

DP-42

DP-51

DP-51

DP-51

DP-66

DP-66

DP-66

DP-72

DP-72

DP-72

DP-75

DP-75

DP-75

DP-81

DP-81

DP-81

DP-83

DP-83

DP-83

DP-89

DP-89

DP-89

DP-91

DP-91

DP-91

DP-92

DP-92

DP-92

DP-103

DP-103

DP-103

DP-108

DP-108

I < ••· l)epth* feet>

I <i • , ' , Priripiple Stress

Pifference

• <¥sf

12.1082 3.2784 4.2583 7.1146 2.7636 4.4239 8.1883 2.2713 2.9543 7.0769 4.3985 5.1997 7.3290 7.9693 8.2095 12.1501 3.4443 3.7945 5.9254 1.8275 1.7564 6.0599 4.6600 5.3406 7.5169 3.9224 4.1908 6.9142 3.8327 4.5926 7.9210 5.6096 7.1776 11.6716 4.0448 4.2357 6.4351 3.4142 5.4127

I.

Multi-Staoe CU Test Results

··•·•·<,_.•·. /\Xic1I Stra.in

6.2 7.0 7.6

10.2 7.0 8.0 8.7 6.0 5.5

11.0 7.0 7.6 5.7 7.0 0.4 7.0 7.0 7.6

10.8 5.9 6.3 14.8 7.0 7.6 11.8 7.0 1.3 6.6 7.0 7.6 5.5 7.0 7.6

11.5 7.0 7.6

11.5 7.3 7.7

I < Effectiv� i t Frictio� • Cp�esiQl'l, l:\ng!e,<I>' . ·•·. c' ··•·

· deg · • ksf

27.9 0.40

23.4 0.55

23.4 0.55

23.4 0.55

25.0 0.44

25.0 0.44

25.0 0.44

25.5 0.40

25.5 0.40

25.5 0.40

20.1 0.91

20.1 0.91

20.1 0.91

30.6 0.64

30.6 0.64

30.6 0.64

24.6 0.32

24.6 0.32

24.6 0.32

26.0 0.35

26.0 0.35

26.0 0.35

15.7 1.27

15.7 1.27

15.7 1.27

7.0 1.53

7.0 1.53

7.0 1.53

19.7 0.70

19.7 0.70

19.7 0.70

24.0 0.90

24.0 0.90

24.0 0.90

25.0 0.40

25.0 0.40

25.0 0.40

19.8 0.69

19.8 0.69

Raba-Kistner

·· .. ·.••·•·•··•··• Total<\ .

1iFricti911 (�olJesipQ, /:\pgle,} .. _ ... ·?

Ji. deg< ·.. ks( .• _•···•.

22.5 0.25

18.5 0.80

18.5 0.80

18.5 0.80

18.0 0.70

18.0 0.70

18.0 0.70

24.0 0.35

24.0 0.35

24.0 0.35

13.0 1.20

13.0 1.20

13.0 1.20

27.0 1.85

27.0 1.85

27.0 1.85

20.0 0.60

20.0 0.60

20.0 0.60

24.0 0.11

24.0 0.11

24.0 0.11

10.3 1.54

10.3 1.54

10.3 1.54

3.9 1.58

3.9 1.58

3.9 1.58

13.0 0.90

13.0 0.90

13.0 0.90

20.0 1.23

20.0 1.23

20.0 1.23

17.0 0.80

17.0 0.80

17.0 0.80

14.8 0.76

14.8 0.76

. .. ....... ···.·•· .. · Effectiye. ·.

()QnsoHdation

··•·Pre�sure.

, .··· ksf •

6.62 1.13 2.31 3.53 1.37 2.80 4.21 0.81 1.56 2.88 2.18 3.96 5.16 1.09 2.03 2.85 1.40 2.02 2.95 0.80 1.48 2.93 2.04 3.82 5.82 1.98 5.21 7.64 2.04 4.02 6.04 2.03 4.05 5.66 1.28 2.49 3.60 2.10 4.48

} ... ·.·· .·.· .. Prihciple !3oring Depth* St�e�s

I N. feet Differenqe I .O, . </: . I i • .... ··• ,. J�f ... ·

DP-108 15 9.2824

DP-113 30 2.9081

DP-113 30 3.9994

DP-113 30 7.5598

DP-126 15 5.4743

DP-126 15 7.3643

DP-126 15 10.7988

DP-128 30 3.8851

DP-128 30 4.1822

DP-128 30 7.0961

DP-144 25 4.5992

DP-144 25 9.8939

DP-144 25 19.0305

DP-152 40 4.2276

DP-152 40 6.0987

DP-152 40 12.0311

DP-156 30 3.5919

DP-156 30 5.0606

DP-156 30 10.2558

DP-161 6 4.0141

DP-161 6 4.8492

DP-161 6 9.0241

DP-171 15 4.1153

DP-171 15 5.8242

DP-171 15 10.8030

DP-178 20 3.5777

DP-178 20 6.4932

DP-178 20 16.6907

DP-182 4 3.8771

DP-182 4 6.7640

DP-182 4 14.5585

DP-187 15 3.9403

DP-187 15 5.1511

DP-187 15 8.6854

DP-195 30 2.3615

DP-195 30 3.7568

DP-195 30 9.1262

DP-198 20 4.5959

DP-198 20 7.3704

Multi-Staae CU Test Results

J½ia:.- Strain

I / .. ••.·. ii

12.1 8.9 7.7 7.5 7.0 7.8 4.5 7.1

10.9 4.2 7.4 7.6

11.8 5.2 6.1 4.2 7.0 8.0 5.2 7.0 7.6

11.0 7.0 7.6 11.2 7.0

10.8 5.1 7.1 8.0

12.3 7.0 7.8 8.5 7.1 7.6 6.1 7.1 7.6

--•. •·• .· • •• · Effective . / friqti9n ··. Q8h1oiio11, Angte, !J,' 1 c' '· · deg .·.. ksf

19.8 0.69

23.3 0.11

23.3 0.11

23.3 0.11

21.8 1.00

21.8 1.00

21.8 1.00

23.0 0.70

23.0 0.70

23.0 0.70

26.8 0.60

26.8 0.60

26.8 0.60

21.5 0.96

21.5 0.96

21.5 0.96

20.5 0.65

20.5 0.65

20.5 0.65

27.1 0.43

27.1 0.43

27.1 0.43

23.2 0.73

23.2 0.73

23.2 0.73

32.1 0.25

32.1 0.25

32.1 0.25

30.6 0.29

30.6 0.29

30.6 0.29

18.1 0.93

18.1 0.93

18.1 0.93

22.4 0.50

22.4 0.50

22.4 0.50

26.0 0.70

26.0 0.70

Ra.ba-Kistner

.. ·.·• .. ··.•·· .. •·•Total>> i x 1•··•·Fr19i1ori·•. coheskm, Angle,$ «. >

· · 9eg .. I. �sf\••

14.8 0.76

12.0 0.50

12.0 0.50

12.0 0.50

12.8 1.60

12.8 1.60

12.8 1.60

12.5 1.10

12.5 1.10

12.5 1.10

22.2 0.15

22.2 0.15

22.2 0.15

13.7 1.15

13.7 1.15

13.7 1.15

13.5 0.80

13.5 0.80

13.5 0.80

30.5 0.30

30.5 0.30

30.5 0.30

17.7 0.80

17.7 0.80

17.7 0.80

19.0 0.45

19.0 0.45

19.0 0.45

28.0 0.10

28.0 0.10

28.0 0.10

11.0 1.20

11.0 1.20

11.0 1.20

12.7 0.32

12.7 0.32

12.7 0.32

20.0 0.65

20.0 0.65

I Effecliye < ·fonspli.datipn

Pres�urer•• · ksf

6.48 2.76 5.22 7.57 2.57 5.11 7.70 3.36 2.71 5.38 3.36 8.25 10.54 2.17 4.31 8.83 2.62 5.43 8.18 1.43 1.91 2.93 2.15 4.35 6.47 2.34 5.36 8.01 1.98 3.76 6.14 1.94 4.60 6.01 2.74 5.82 9.56 2.67 5.30 l>Y<-•····· ·._< 'Prinoiple

L �lw.•t 1··-[J�pth* IStres� 1•-••· f��t\••·••· Diffe[E>DC6

. .. ·•· .. •· -.-.. i>ksf ..

DP-198 20 13.5152

DP-202 30 3.2708

DP-202 30 3.9836

DP-202 30 8.2075

DP-215 20 2.1936

DP-215 20 3.2518

DP-215 20 8.2969

DP-218 40 4.8103

DP-218 40 6.3146

DP-218 40 12.0712

DP-221 40 4.8533

DP-221 40 9.2930

DP-221 40 19.5810

DP-227 8 6.1887

DP-227 8 8.0135

DP-227 8 12.1376

DP-229 30 3.7814

DP-229 30 4.6853

DP-229 30 9.9966

DP-233 15 6.5722

DP-233 15 7.2494

DP-233 15 11.4984

DP-234 40 4.2867

DP-234 40 5.9259

DP-234 40 11.0639

DP-242 6 5.1908

DP-242 6 5.9166

DP-242 6 8.5867

DP-243 6 2.7539

DP-243 6 3.1003

DP-244 40 0.0000

DP-244 40 3.1175

DP-244 40 6.0546

DP-252 15 8.1384

DP-252 15 11.4970

DP-252 15 18.2401

DP-280 15 1.8957

DP-280 15 3.6563

DP-280 15 7.6182

Multi-Staae CU Test Results

.:·.:./.::._<·::·: 1. i .Effective>Axial f ric(i()n C6h�sit)11, §tfai�

%. ·••1ngletf ·•. •.. S' i I,"'" ';,•,,,;" --; deg•• > •·.· \ksf I·- ,.-·,_."' ·._ ·-.

7.1 26.0 0.70

7.1 12.7 0.93

7.7 12.7 0.93

12.2 12.7 0.93

5.7 30.0 0.25

6.1 30.0 0.25

12.4 30.0 0.25

7.1 22.0 0.59

7.6 22.0 0.59

6.8 22.0 0.59

7.0 27.5 0.40

7.6 27.5 0.40

8.5 27.5 0.40

7.0 22.0 0.98

7.6 22.0 0.98

10.8 22.0 0.98

7.0 16.0 1.02

7.6 16.0 1.02

11.8 16.0 1.02

7.0 22.0 0.83

7.6 22.0 0.83

9.7 22.0 0.83

7.0 22.0 0.63

7.6 22.0 0.63

7.1 22.0 0.63

7.0 14.2 1.41

7.6 14.2 1.41

11.0 14.2 1.41

7.0 12.1 0.71

7.6 12.1 0.71

0.0 21.5 0.35

7.1 21,5 0.35

5.1 21.5 0.35

7.0 31.5 0.42

7.6 31.5 0.42

8.8 31.5 0.42

5.7 27.0 0.34

4.9 27.0 0.34

12.1 27.0 0.34

Raba-Kistner

••.••-rota! /·•·•i·< Fr.istiqn< f?Be�ion, .l\ggl_e,, ,p ·· c< .dE>g>\ ' ksf

20.0 0.65

7.5 1.10

7.5 1.10

7.5 1.10

20.5 0.25

20.5 0.25

20.5 0.25

14.2 0.45

14.2 0.45

14.2 0.45

21.0 0.13

21.0 0.13

21.0 0.13

14.0 1.80

14.0 1.80

14.0 1.80

15.0 0.60

15.0 0.60

15.0 0.60

18.0 1.30

18.0 1.30

18.0 1.30

17.0 0.61

17.0 0.61

17.0 0.61

7.0 1.99

7.0 1.99

7.0 1.99

5.2 1.07

5.2 1.07

7.0 0.85

7.0 0.85

7.0 0.85

27.0 1.40

27.0 1.40

27.0 1.40

21.0 0.24

21.0 0.24

21.0 0.24

Effl?ctjve Cbnsolj�ation1 ·.· Pres�µfe> < .ksL ... ·

7.90 2.54 5.27 8.05 1.28 2.53 5.15 3.35 7.90

11.73 3.89 7.98

11.97 2.58 5.25 7.66 2.50 4.70 7.20 2.76 4.22 6.24 2.64 5.12 7.78 2.68 5.23 7.43 1.98 3.82 0.00 4.97 7.71 2.18 4.26 6.30 1.45 2.25 4.31

Project No. AMAOB-115-00

�bring No ...

DP-292

DP-292

pepth* feet

Prinqiple Stres.s

Difference ksf

3.6782 6.0851

Multi-Sta e CU Test Results

7.0 26.5 0.50 20.0 0.68 1.71

7.9 26.5 0.50 20.0 0.68 3.75

*Depth below the top of levee surface elevation existing at the time of our field study.

Multi-stage CD tests were used to determine total soil strength parameters. During CD testing, each stage was subjected to an effective consolidation pressure of about 1, 2, and 3 times the in-situ confining stress. The results of the multi-stage CD tests presented graphically and numerically in Appendix B, are also summarized in the table below.

I> --:-,-, •· Boring

,··.·•···No.x> ii ....... ·

DP-19

DP-19

DP-19

DP-34

DP-34

DP-34

DP-99

DP-99

DP-99

DP-100

DP-100

DP-100

DP-130

DP-130

DP-130

DP-137

DP-137

DP-137

DP-148

DP-148

DP-148

DP-189

DP-189

DP-189

DP-190

I ''· < Qepth*

I/ Je�t I

Multi-Staae CD Test Results Principle Stres.s l)i(ft.renoe l,•.•···<�Sf

2.30 2.24 6.47 0.75 1.52 5.15 3.84 3.94 8.27 3.82 5.35 8.94 3.52 5.61

12.94 3.15 4.30 8.46 4.54 5.35

14.66 2.91 4.80

13.60 3.56

: < .. ,0/< ,.

, ,'.;',"\i-ii

I i" ¼ < ··.·'.>) 5.7 6.0 12.3 6.3 6.7

14.0 6.0 6.3

10.7 5.0 6.2

10.4 5.8 5.3 6.7 5.2 6.3 16.7 7.0 7.8 6.9 6.0 6.4 16.5 5.8

1<•. < < .. Tota1·,.•<\ •.. ·> 1 fricti9:ri • C6�t.sio.n, Anglt1,.�. . .;c;< • deg ·,. ksf ·

16.0 0.70

16.0 0.70

16.0 0.70

19.8 0.00

19.8 0.00

19.8 0.00

20.3 1.04

20.3 1.04

20.3 1.04

24.0 0.90

24.0 0.90

24.0 0.90

21.0 0.70

21.0 0.70

21.0 0.70

19.0 0.72

19.0 0.72

19.0 0.72

11.9 1.39

11.9 1.39

11.9 1.39

29.0 0.23

29.0 0.23

29.0 0.23

28.0 0.48

Raba-Kistner

!:,f1'�ctiy e ..

Con§()lid.ition.

> Pres��r<l ..

. <k�f•

0.71 1.46 2.85 0.71 1.43 2.87 0.72 1.46 2.86 0.71 1.47 2.89 1.31 2.88 5.75 1.17 2.32 3.88 2.14 4.32 8.62 1.33 2.62 5.23 1.07

Project No. AMAOS-115-00

BoriQ�\ No.

.··. 1 ..• I Pepth� , . feet I·" ..... -. .

() . \ I>. /> -> ,' _,: ·:<

DP-190 15

DP-190 15

DP-199 20

DP-199 20

DP-199 20

DP-238 40

DP-238 40

DP-238 40

DP-249 30

DP-249 30

DP-249 30

DP-269 30

DP-269 30

DP-269 30

Multi-Staae CD Test Results Prihpiple Stress

Pifffclr�nce j/.ksf· 1 -

6.22 12.57 3.66 6.00 13.93 5.11 8.83

21.63 3.47 4.85 11.84 3.22 5.90

16.58

·•.•k;; I<> . .. Ia Stra)n

1·-•. _ •• ·.·•

4.9 10.6 6.0 5.3

11.5 6.0 7.6 12.8 5.7 6.0

15.8 5.8 6.1 9.3

1·•· Total }<'•· E:�ective·.••t frigtion Collfclsion, Cc:,n�plj<Jatio.n Angl<l, Ai- C · Prfcl.iisur<l deg ksf_·•.-· ./. ksf ••··•··

28.0 0.48 2.15

28.0 0.48 4.32

27.0 0.45 1.28

27.0 0.45 2.62

27.0 0.45 5.14

24.2 0.68 2.15

24.2 0.68 4.35

24.2 0.68 8.62

11.5 1.05 1.83

11.5 1.05 3.58

11.5 1.05 7.29

25.0 0.30 1.74

25.0 0.30 3.69

25.0 0.30 7.13

•oepth below the top of levee surface elevation ex1st1ng at the time of our field study.

Direct shear tests have been completed on selected samples. These samples were subjected to various normal loads and sheared at a rate of 0.007 inches per minute. The results of the direct shear tests presented graphically and numerically in Appendix B, are also summarized in the table below.

:- ' .·'i_--··-,-c<i-

Borin?·

• .\ No ....•

DP-20

DP-46

DP-60

DP-66

DP-71

DP-80

DP-104

DP-120

DP-124

DP-151

DP-156

DP-159

DP-169

DP-173

I :

Depth* <fe�t ·••·

Direct Shear Test Results . •·· .. _··• •Max . ·_ .... •

.i ) . ' Normal· Friction •.• I Stress

S�e.ar Cohesion Angle, <j, Ksf ··visµa1·c1assification! >psi / ?\r<ll,S / . deg• > ksf.. -------_ •·.·. ._\_.· .

14.4 2.46 0 50.0 Siltv Clav

10.1 1.73 0 49.9 Silty Clay

29.0 3.12 0 36.8 Siltv Sand

32.1 3.27 0 35.3 Clayey Sand

8.3 1.30 0 47.2 Silty Sand

8.3 0.81 0 33.8 Clavev Sand

22.0 2.56 0 38.9 Clayey Sand

19.4 2.43 0 41.0 Clavev Silt

23.4 2.20 0 33.2 Silty Sand

31.5 2.26 0 26.4 Siltv Clay

8.5 1.32 0 47.3 Siltv Clav

23.1 2.28 0 34.4 Clayey Sand

12.6 2.35 0 52.3 Clavev Silt

18.6 2.07 0 37.8 Silty Clay

Project No. AMAOB-115-00

,' :',<·.::.:_>·.?··.··. I> . .. -.. ·.•·••·1, . __ __.-,,, ' ElCJring Depth� feet ' No.

• DP-179 15

DP-181 16

DP-189 10

DP-190 10

DP-195 35

DP-197 10

DP-220 20

DP-228 10

DP-229 25

DP-236 25

DP-239 40

DP-242 40

DP-243 25

DP-248 20

DP-250 25

DP-265 30

DP-268 40

Direct Shear Test Results i', :' ,' · .. ··\>_>,>' MaxNqrmal

. ,' ', · ·-_- ., $h�ar, /ltress •. Stresspsi ,.. ksf · •··· ' ',, ,,_'_'

12.0 1.17

14.7 1.37

10.0 1.68

10.0 1.24

31.2 1.71

8.3 1.32

18.0 1.35

10.5 1.60

23.7 2.28

25.0 3.34

40.5 4.42

36.7 3.34

23.1 2.55

16.9 1.89

18.6 1.73

25.2 1.64

39.6 3.93

Cohesion , Ksf <

':__-_-, :>,"i:>

I fri9tiQr) Angl�, $ . deg ..

34.0 32.8 49.4 40.7 20.9 48.0 27.6 46.7 33.8 42.8 37.1 32.4 37.4 37.9 32.8 24.3 34.5

... I I}. <· /, <' Visual• Classification.. . · ..

Clayey Sand Siltv Clav Siltv Clav Clayey Silt Siltv Clav Siltv Clay Silty Clay Clavev Silt

Clavev Sand Clayey Silt Clavev Silt Silty Clay Siltv Sand Clavev Silt Clayey Silt Siltv Clav

Clavev Sand •Depth below the top of levee surface elevation ex1st1ng at the time of our field study.

CONSOLIDATION TESTS

One-dimensional incremental consolidation tests were performed on selected samples to define the compressibility characteristics of both the existing fill soils and the bearing soils along the planned levee alignment. Results of the consolidation tests were also used to develop the SHANSEP parameters used in our stability analyses. Results of the consolidation tests are presented graphically and numerically in Appendix B and are also summarized in the following table.

Consolidation Test Results

-::--·-- .·.· .. •· I Initial l�itial l<.;;f··• •··.··t:i} 1\ocR\ \)?�(\ 1•-•·-•.;·••·•(ti••·

.: "_- /-".'·.··:'· ' BCJ.ring Depth* ' 1'dN> i1 ... , •••••

, J .. iquid·.· '•••·· No> •,Jeet :Y_tot_ai,:.:i> .·

1•.•·•·<·•·"< .. Limit_.

,·:_,-. -,._ .,:._ . •ocf .•• I ... pcf· ... · ..

DP-1 2 100.7 115.6 0.2 2.0 8.7 0.113 0.026 51

DP-9 6 93.1 119.6 0.7 1.6 2.2 0.108 0.012 47

DP-17 2 106.0 125.1 0.3 0.076 0.017

DP-23 2 98.3 123.5 0.2 4.4 17.8 0.129 0.019

DP-27 8 99.1 119.0 1.0 0.043 0.007

DP-33 4 110.0 132.0 0.5 5.0 9.5 0.068

DP-40 5 107.7 127.4 0.6 6.0 9.4 0.077 0.021

DP-47 20 94.4 121.3 2.4 3.2 1.3 0.098 0.030

DP-52 8 94.6 116.4 0.9 3.6 3.9 0.142 0.023 59

DP-62 1 105.3 125.9 0.1 4.0 31.8 0.060 0.018

Raba-K.istner

Consolidation Test Results ___ .-·-- . "" ·_< .. ·-.- . ," ··,:···: --·-':'"·.: --Jnitial._ •.. · · lniUc1I .. · . < <··,·•.•. Ii :_. ·--·_.

< . > BiJring Depth*. Po. ·., . Pc/

· .. >.liquid.·, I ()CR

.. · c,, .•.•.. ·-:.'}'di-v - - - •. Ytotal i < umit .. No, 1 \ fee,t · _.·.· ··•·. ncf ••• ncf

DP-65 8 95.6 121.8

DP-73 4 96.7 113.6

DP-81 8 97.6 116.1

DP-85 6 93.9 119.1

DP-89 8 106.0 126.5

DP-93 6 93.7 119.9

DP-102 6 109.7 128.8

DP-107 2 100.9 125.3

DP-115 8 103.4 123.5

DP-116 8 111. 7 128.4

DP-118 10 101.2 115.3

DP-123 4 102.2 124.3

DP-128 6 104.4 122.3

DP-141 4 105.5 126.8

DP-152 6 108.4 125.0

DP-156 4 105.0 124.4

DP-159 4 104.9 124.2

DP-167 4 101.6 123.7

DP-170 2 101.6 125.6

DP-175 6 103.1 127.9

DP-181 2 101.5 124.4

DP-187 10 99.2 122.1

DP-197 4 99.0 123.3

DP-204 10 91.4 117.7

DP-215 8 105.6 127.6

DP-218 4 106.5 124.9

DP-221 8 88.1 117.2

DP-225 10 109.9 129.1

DP-231 4 104.1 116.7

DP-244 10 97.1 122.2

DP-270 10 90.5 118.3

ksf ··• . ... -ksf

1.0 4.0

0.5 4.0

0.9 4.0

0.7 5.0

1.0 3.0

0.7 5.5

0.8 3.5

0.3 4.0

1.0 4.2

1.0 3.4

1.2 3.0

0.5 4.4

0.7 3.3

0.5 4.2

0.8 3.0

0.5 4.2

0.5 3.3

0.5 4.4

0.3 7.0

0.8 6.0

0.2 5.2

1.2 4.0

0.5 5.0 1.2

1.0 3.0

0.5 4.1

0.9 4.4

1.3 3.0

0.5 2.0 1.2

1.2 1.8

4.1 8.8 4.3 7.0 3.0 7.6 4.5

16.0 4.3 3.3 2.6 8.8 4.5 8.3 4.0 8.4 6.6 8.9

27.9 7.8

20.9 3.3

10.1

2.9 8.2 4.7 2.3 4.3

1.5

0.124 0.028

0.064 0.011

0.112 0.007

0.105 0.028

0.050 0.006

0.110 0.009

0.069 0.020 0.076

0.115 0.022

0.049 0.013

0.057 0.010

0.085 0.020

0.088 0.033

0.063 0.023

0.062 0.011

0.051 0.013

0.071 0.019

0.060 0.011 0.077 0.072

0.086 0.021

0.114 0.018

0.081 0.016

0.118 0.015

0.078 0.013

0.070 0.023

0.233 0.040

0.071 0.008

0.080 0.008

0.129 0.021

0.102 0.006

Note: The compression and recompress1on md1ces shown are "modified" md1ces as described by Holtz and Kovacs, 1981. These indices were taken from a strain�log P curve, rather than an e�log P curve.

*Depth below the top of levee surface elevation existing at the time of our field study.

HYDRAULIC CONDUCTIVITY (PERMEABILITY) TESTS

Hydraulic conductivity (permeability) tests were performed on relatively undisturbed Shelby tube samples obtained from 40 selected samples of cohesive-type soils. These cohesive soil samples were tested for vertical hydraulic conductivity to assess the seepage velocities of the embankment and cohesive subsurface soils. A calculation summary sheet for each hydraulic conductivity (permeability) test is presented in Appendix B. The results are also summarized in the table below.

Project No. AMAOS-115-00

> ',Bgring .

No.

DP-2

DP-4

DP-7

DP-11

DP-18

DP-22

DP-26

DP-33

DP-37

DP-46

DP-62

DP-65

DP-66

DP-82

DP-87

DP-92

DP-97

DP-99

DP-106

DP-112

DP-117

DP-118

DP-118

.. Hydrc1ulic·.•Depth Conductivityfeet .• ' .', ._, 1-- cm/sec

20 9.70E-08

35- 50 1.0SE-03

35-50 2.32E-03

2 6.SOE-07

10 6.00E-08 2 3.00E-07

30 - 50 5.85E-04 6 3.00E-08 6 4.20E-08 0 7.?0E-08 2 1.00E-07

10 5.?0E-08 35 - 50 7.01E-04

8 7.20E-08 4 8.10E-07

2 2.SOE-08

25 - 35 1.43E-03 10 6.50E-08 6 6.40E-07 8 1.20E-07

25-35 2.65E-03 2 5.60E-06

25-50 1.58E-03

Permeability Test Results •• < i' '> HYdf?UliC I sofirig ,:, <-- '',:: ,;o HydrauJic§oring I Qeptl, Depth.

, Co11du9Uvity Conduc\ivity No: ·. 1 Jee! yNo,> ·. ·.:f�et: .. ·:'_:

I•• •.> ·· . . cm/sec·.· .. I • .cm/sec

DP-122 10 1.10E-06 DP-208 25- 45 1.69E-03

DP-122 30- 50 1.41E-03 DP-215 4 7.?0E-08

DP-124 30- 50 2.31 E-03 DP-218 15 3.30E-08

DP-126 30 - 50 2.05E-04 DP-221 2 2.30E-08

DP-129 4 4.60E-08 DP-226 4 3.90E-08

DP-142 8 1.20E-08 DP-229 2 8.10E-07

DP-150 15 2.90E-08 DP-233 25 - 50 1.32E-03

DP-156 15 3.00E-08 DP-234 8 2.35E-08

DP-159 10 5.50E-08 DP-242 25 1.20E-08

DP-165 30- 50 1.31E-03 DP-244 2 4.00E-08

DP-166 20- 35 1.64E-03 DP-252 2 6.30E-08

DP-168 6 6.?0E-08 DP-252 25 - 45 7.68E-04

DP-171 4 1.00E-07 DP-253 25 - 50 1.56E-03

DP-174 6 6.70E-07 DP-256 15 2.SOE-08

DP-177 30 - 50 1.SOE-03 DP-268 15 1.?0E-06

DP-183 2 7.50E-07 DP-278 30- 50 2.63E-03

DP-183 30- 50 6.85E-04 DP-280 25- 50 1.54E-03

DP-187 6 8.30E-07 DP-282 30 - 50 2.68E-03

DP-188 25- 45 1.29E-03 DP-293 40- 50 1.25E-03

DP-197 8 7.30E-08 DP-296 30- 50 2.06E-03

DP-197 25- 45 1.46E-03 DP-299 30- 50 1.56E-04

DP-202 40 9.30E-08

DP-206 25- 45 2.00E-04

Based on the USAGE EM 1110-2-1901 Seepage Analysis and Control for Dams indirect methods for determining hydraulic conductivity may also be used. For uniform, loose clean sands classified as SP (poorly graded sand), the Hazen2 equation is suggested for use. The following graph presents the results calculated using the Hazen equation.

2 Hazen, Allen, "Discussion of 'Dams on Sand Foundations' by A.G. Koenig", Trans. American Society of Civil Engineers, Vol. 73, p. 199, 1911.

Raba -.Kistner

0.1

A

0.01 --�-

K values calculated using Hazen formula

0.001 .I J .L. ..I. I I L .. J ... .... I. ... I L L. L.

SITE DESCRIPTION

10 20 30 40

Samples Tested

GENERAL SITE CONDITIONS

The proposed improvements to the Donna Pump to Brownsville Levee Reach include 48.5 miles of the existing levee alignment located within Cameron County, as well as a small portion of Hidalgo County (approximately 2.5 miles) just west of the Cameron County line, for a total 51 miles. At the time of our field activities, the project site can generally be described as an earthen levee with grass-covered slopes and a caliche-surfaced roadway spanning the levee crest. During our site reconnaissance, heavily vegetated areas were observed along several portions of the existing levee alignment. These vegetated areas were cleared by USIBWC representatives prior to commencement of our drilling operations. Undeveloped, vegetated land was observed along both sides of the existing levee alignment. Irrigation ditches were observed along some portions of the alignment. These ditches were observed to be both dry and wet (full of water) at the time of our field activities.

SITE GEOLOGY

The levee project is located within the confines of the Gulf of Mexico Basin, which formed from down-faulting Paleozoic basement rocks during the break-up of Pangaea in the Late Triassic Period'A_ Continental highlands provided a continued source of sediments into the basin causing

3 Chowdhury, A., Turco, M., Geology of the Gulf Coast Aquifer, Texas; Proceedings of the Gulf Coast Aquifer Conference, Corpus Christi, Texas Water Development Board Report 365 4 Morrison, RB., 1991, Quaternary nonglacial geology:conterminous U.S.; The Geology of North America; v. Kw2. Geological Society of America, Chp. 19, Quaternary geology of the Gulf of Mexico Coastal Plain, & Plate 8.

Raba -Kistner rapid accumulation of thick sediment deposits in a fluvial-deltaic or shallow-marine environment3·4 •

Repeated sea-level changes with continued basin subsidence generated cyclic assemblages of river, eolian, and lake sediments. Eighteen major depositional episodes have been mapped in the Gulf of Mexico Basin using lithofacies, thickness, stratigraphic architecture, and facies association 3.

The Quaternary Pleistocene sedimentary units have been separated into the early Pleistocene Willis Sand (has not been identified in the Rio Grande area) overlain by the Lissie Formation, which is comprised of the lower Bentley Formation and upper Montgomery Formation. The Beaumont Clay overlies the Lissie Formation and is a late Pleistocene deposit. The Pleistocene sediments represent erosional and depositional sequences correlating to periods of glaciations and coincident sea-level variations".

The Lissie Formation is unconformably packaged between the underlying Miocene Goliad Sand and the overlying Beaumont Clay".4 _ The Lissie Formation outcrops in a 30-mile wide band parallel to the coast with sediments representing flood plains and deltas, deposited at the mouth of rivers". The sediments consist of reddish, orange, and gray fine-to-coarse-grained, cross bedded sands and gravelly sands3

. Caliche beds often distinguish the base of the Lissie Formation. This Formation is absent near the Rio Grande mouth but outcrops east and west of the Rio Grande mouth4

The Beaumont Clay is comprised of poorly bedded, marly clay with interbedded lenses of sand that were deposited as natural levees and deltas that coalesced as river mouths migrated, and in marine and lagoonal waters located in the bays and embayments3'4. The clay is reddish-brown poorly drained clay, intermixed with lenses of fine sand, decayed organic matter, and buried organic-rich zones that contain calcareous and ferruginous nodules3

• The Beaumont Clay exhibits plastic and compressible characteristics and varies from five to over several hundred meters thick3

Eolian and fluvial-deposited sediments dissecting into, filling in, and covering outcrops of Beaumont Clay dominate the Holocene Epoch4

. The Holocene depositional systems represent terrace gravels, channel and point bar deposits, and sand dunes with grain sizes ranging from clay to gravel. The terrace gravels are a result of migrating channels dissecting into the underlying sediments, exposing relict deposits and the channel and point bar deposits represent infilling of channels5

• The down-cutting and infilling c¥cles correlate to sediment loads received from continental drainages during climatic fluctuations . Eolian sand deposits cover the surficial outcroppings of the underlying deposits and form sand sheets and dunes comprised of relatively clean sands4

According to the Soil Survey of Cameron and Hidalgo Counties, Texas, published by the United States Department of Agriculture - Soil Conservation Service, in cooperation with the Texas Agricultural Experiment Station, the existing levee alignment appears to be located within the Laredo-Olmito; Rio Grande-Matamoros; and Harlingen soil associations. The Laredo-Olmito soil association consists of nearly level to gently sloping, well-drained and moderately well-drained

5 Doser, D.I., Langford, R.: Baker, M. and Oena-Ornela, 0., 2001, Studies of grain size variations in fluvial sediments of the Rio Grande using magnetic techniques, Proceedings of the Symposium on the Application of Geophysics to Environmental Engineering Problems (SAGEEP 2001 - Denver, on CD-ROM. paper ASP-5 silty clay loams and silty clays. The Rio Grande-Matamoros soil association consists of nearly level to gently sloping, well-drained and moderately well-drained silt loams and silty clays. The Harlingen soil association consists of level and nearly level, moderately well-drained clays. The corresponding soil symbols within the existing levee alignment appear to be 33, Laredo silty clay loam; 45, Pits, borrow; 62, Rio Grande silt loam; 63, Rio Grande silty clay loam; CA, Camargo silt loam; CC, Camargo silty clay loam; CE, Cameron silty clay; GR, Grulla clay; HA, Harlingen clay;

LAA, Laredo silty clay loam; LEA, Laredo-Reynosa complex; MA, Matamoros silty clay; OM, Olmito silty clay; RR, Rio Grande silt loam; and RT, Rio Grande silty clay loam.

SEISMIC COEFFICIENTS

Based upon a review of Section 1613 Earthquake Loads of the 2006 International Building Code (IBC), the following information has been summarized for seismic considerations associated with the planned levee alignment. Note that the project covers a substantial geographic range. As such, the values taken from the I BC charts also vary across the project. The following parameters are presented as a range and represent the western most boring (DP-59) to the eastern most boring (DP-277); these values presented are for Boring DP-59 and Boring DP-277, respectively.

• Mapped Maximum Considered Earthquake Ground Motion for a 0.2 sec., Spectral Response Acceleration (Figure 1613.5(1)): s. = 0.049 to 0.041g.

• Mapped Maximum Considered Earthquake Ground Motion for a 1 sec., Spectral Response Acceleration (Figure 1613.5(2)): S1 = 0.013 to 0.012g.

STRATIGRAPHY

The subsurface conditions observed in the borings performed for this study varied along the entire length of levee. In general, fill materials associated with the existing levee were observed overlying naturally deposited soils common to the area.

Embankment fill soils within the existing levee: Levee fill soils consisting of locally available soils were observed at the levee crest extending to the natural ground elevations. These fill soils were observed at thicknesses ranging from about 1 to 18 feet. The vast majority of the fill materials observed in the borings performed for this study consisted of lean clays (CL). The remaining the fill materials were comprised of fat clays (CH), sands (SP and SP-SM), and silts (ML).

The fat clays observed within the existing levee are considered highly to very highly plastic, with measured plasticity indices of 25 to 52 percent, indicating a high…