final-report-URS-geotech.pdf

F I N A L R E P O R T

GEOTECHNICAL AND HTRW

INVESTIGATION

GREEN BROOK FLOOD RISK MANAGEMENT PROJECT

SEGMENTS B2, B3 AND B4

MIDDLESEX, NEW JERSEY

Prepared for:

U.S. ARMY CORPS OF ENGINEERS

NEW YORK DISTRICT

December 5, 2012

Prepared by:

1255 Broad Street. Suite 201 Clifton, New Jersey 07013

Project No: 11020912

TABLE OF CONTENTSTABLE OF CONTENTSTABLE OF CONTENTSTABLE OF CONTENTS

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Executive Summary ......................................................................................................................... ES�1

Section 1 – Introduction ........................................................................................................................... 1�1

1.1 GENERAL ..................................................................................................... 1(1

1.2 PROJECT OVERVIEW ................................................................................ 1(1

1.3 SCOPE OF INVESTIGATION ..................................................................... 1(1

1.4 REPORT ORGANIZATION ......................................................................... 1(2

Section 2 – Subsurface Investigation and Site Characterization ......................................................... 2�1

2.1 GENERAL ..................................................................................................... 2(1

2.2 SUBSURFACE INVESTIGATION ............................................................. 2(1

2.2.1 Geotechnical Borings and HTRW Sampling ............................... 2(1

2.2.2 Borehole Permeability Testing ..................................................... 2(2

2.2.3 Geotechnical Laboratory Testing ................................................. 2(3

2.2.4 HTRW Laboratory Testing .......................................................... 2(3

2.3 SITE CHARACTERIZATION ...................................................................... 2(5

2.3.1 Local Geology .............................................................................. 2(5

2.3.2 Generalized Subsurface Conditions ............................................. 2(5

2.3.3 Groundwater Condition ............................................................... 2(6

Section 3 – Results of Geotechnical Investigation ............................................................................... 3�1

3.1 GENERAL ..................................................................................................... 3(1

3.2 MATERIAL PARAMETERS ........................................................................ 3(1

3.3 SEISMIC CONSIDERATIONS .................................................................... 3(2

3.4 GEOTECHNICAL RECOMMENDATIONS ............................................... 3(2

3.4.1 Flood Walls .................................................................................. 3(2

3.4.2 Closure Gate ................................................................................. 3(3

3.4.3 Levee ............................................................................................ 3(3

Section 4 – Results of HTRW INVESTIGATION ...................................................................................... 4�1

4.1 GENERAL ..................................................................................................... 4(1

4.2 DATA VALIDATION AND VALIDATION RESULTS ............................. 4(1

4.3 NJDEP ELECTRONIC DATA DELIVERABLES ....................................... 4(1

4.4 ANALYTICAL RESULTS ............................................................................ 4(2

Section 5 – Limitations ............................................................................................................................ 5�1

TABLE OF CONTENTSTABLE OF CONTENTSTABLE OF CONTENTSTABLE OF CONTENTS

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LIST OF TABLES

Table 2(1 Summary of Laboratory Tests Performed

Table 2(2 Summary of Environmental Soil Sampling Performed

Table 2(3 Summary of Groundwater Observations

Table 3(1 Summary of Material Parameter Values

Table 4(1 Summary of Data Validation Qualifiers Applied to HTRW Data

Table 4(2 Summary of Soil Exceedances of NJDEP Standards

LIST OF FIGURES

Figure 1 Site Location Map

Figure 2 Boring Location Plan – Key Map

Figure 3 Boring Location Plan – Sheet 1 of 5

Figure 4 Boring Location Plan – Sheet 2 of 5

Figure 5 Boring Location Plan – Sheet 3 of 5

Figure 6 Boring Location Plan – Sheet 4 of 5

Figure 7 Boring Location Plan – Sheet 5 of 5

Figure 8 Generalized Subsurface Profile Along the Alignment

LIST OF APPENDICES

Appendix A GPR Survey Sketches

Appendix B PID Readings

Appendix C Test Boring Logs

Appendix D Permeability Calculations

Appendix E Geotechnical Laboratory Testing Results

Appendix F Chain of Custody Forms

Appendix G Data Validation Memorandum

Appendix H HTRW Laboratory Testing Results

EXECUTIVE SUMMARY

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General:

This report presents the results of a geotechnical and hazardous, toxic, and radiological waste

(HTRW) investigation performed by URS for the design of Segments B2 through B4 of the

Green Brook Flood Risk Management Project (GBFRMP). The line of protection of Segments

B2 through B4 of the GBFRMP is located in the Borough of Middlesex, NJ.

Subsurface Conditions:

As a part of this investigation a total of 13 test borings were performed. The subsurface soils consist of a 2 to 5 foot thick layer of sandy fill underlain by about a 15 to 30 foot thick layer of sand with varying amounts of silt (Stratum 2), followed by approximately a 5 to 10 foot thick layer of completely weathered rock, and siltstone bedrock. Based on borings B(1, B(10 and B(

13, it appears that top of bedrock elevation is approximately +2 ft at the northern end of Segment

B(2 and gradually slopes down to approximately elevation (1 ft until slightly south of Bound

Brook Road. The top of rock then slopes upward to approximately elevation +19 ft at the end of

Segment B3. The anticipated bedrock profile as described above is presented in Figure 8.

Groundwater level measurements made in the borings indicated that groundwater level ranges from approximately elevation 27 to 33 ft (NGVD 29). These readings do not reflect any seasonal changes in groundwater levels that may take place.

Geotechnical Material Parameters:

The primary geotechnical material parameters required for the global stability, foundation and seepage analyses are the shear strength, unit weight and permeability (hydraulic conductivity) of the foundation and fill (for levee) materials. The shear strength and unit weight values were estimated using the standard empirical correlations based on the SPT N(Values obtained from test borings. The estimated friction angle using standard empirical correlations ranges from 32 degrees to 35 degrees for the natural sandy soils (Stratum 2). Therefore, a conservative effective stress friction angle of 32 degrees is recommended for the natural sandy soils (Stratum 2) which is the primary soil stratum overlying the bedrock. Based on the results of borehole permeability tests, the permeability of the sandy (with fines content generally ranging from 10% to 35%) soils

(Stratum 2) ranges from approximately 9 × 10 (4 cm/sec to 4 × 10 (5 cm/sec. A summary of material properties for all soil stratums (including compacted fill) is presented in Table 3(1.

Based on the laboratory test results, the unconfined compressive strength of intact rock samples ranged from 694 to 9,360 psi, with an average of approximately 5,000 psi. However, considering the rock mass is highly fractured (i.e., borings B(1 and B(13 ( RQD = 0%, and B(10 – RQD =

10%), the compressive strength of the rock mass is typically only about 15% of the intact rock strength. Therefore, the recommended compressive strength of the shale rock mass at the project site is 750 psi. Based on the laboratory test results, the recommended unit weight of shale rock is

160 pcf. An allowable bond strength (grout / rock interface frictional resistance) of 50 psi is recommended for the design of caissons socketed into rock.

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Seismic Considerations:

The recommended seismic site classification is Site Class “D” for this project site. Considering that the sandy soils below the groundwater level are generally medium dense to dense, earthquake induced liquefaction is not likely to be a concern at this site.

T(Walls and Closure Gate:

Considering the anticipated relatively large uplift and lateral loads, deep foundations are likely to be the most feasible foundation system for the T(Walls and closure gate monoliths. Deep foundations can be either driven piles bearing on bedrock or drilled caissons socketed into bedrock. Considering that the depth to bedrock may range from 20 ft to 40 ft below the existing ground surface, the uplift capacity (on the order of 10 to 20 tons) of the piles driven to bedrock may not be sufficient especially at locations where bedrock may be encountered at a depth of 20 ft.

Alternatively, although significantly more costly than driven piles, the T(Walls and closure gate monoliths can be supported on drilled caissons socketed into bedrock. Depending on design loads, spacing, total cost and construction considerations; the drilled caissons can either be mini( caissons with nominal diameters ranging from 8 inches to 12 inches, or large diameter caissons ranging from 24 inches to 36 inches in diameter. Depending on the diameter and rock socket length, the allowable compression capacities of mini(caissons and large diameter caissons may range from 70 to 100 tons, and 120 to 300 tons; respectively. It should be noted that calculations for compression, uplift and lateral capacities should be performed.

Further, considering that foundation soils are sandy with varying amounts of silt, it will be likely that a sheet pile cut(off will be required to control the under seepage and exit hydraulic gradients.

I(Walls:

Typically, I(walls are driven steel sheet pile walls with reinforced concrete cap above the ground surface. Generally the required minimum embedment length of sheet piles below the existing ground surface may range from 2 ½ to 3 times the height of the flood wall. Therefore, considering that bedrock at some locations may be encountered at a depth of 20 ft below the ground surface, if the height of the I(wall exceeds about 5 ft to 8 ft, it may not be feasible to achieve the required minimum embedment. In such situations, a T(Wall or I(Wall with drilled in soldier piles and sheet pile lagging can be considered as alternative options. One of the advantages of the I(Wall is that a separate cut(off wall will not be required.

Levee:

It appears that towards the end of Segment B3, a portion of the line of protection will consist of a levee, with the height ranging from 12 ft to 15 ft above the existing ground surface. Based on our experience with similar projects, it is anticipated the levee will have a ten(foot wide top and

2.5H:1V side slopes. Based on test borings performed on the protected side of the line of protection, foundations soils are generally medium dense to dense sandy soils. Further, except for isolated pockets of soft and/or loose surficial soils (top soils) no distinct layer of soft

I:\Projects\11020912(GB&SegmetB2&B3&Geotech)\Geotech&report\final report&GB&segments_11_19_12.doc ES(3 compressible soils was encountered at the site. Therefore, deep(seated failure (global stability) of the levee will not likely to be a concern.

Further, considering that foundation soils are sandy with varying amounts of silt, it will be very likely that a sheet pile cut(off or a cut(off trench filled with compacted core material will be required to control the under seepage and exit hydraulic gradients. However, it should be noted that excavations for a cut(off trench may extend below the groundwater level.

It is recommended that the levee embankment be constructed using compacted fill material such as silty sand and/or clayey sand which usually has characteristics similar to that outlined in

Section 3.4.3.

Summary of HTRW Investigation:

Environmental soil samples were collected from the 13 boring locations and field screened with a photoionization detector (PID) for organic vapors. At every boring location only background or low PID readings were observed. Within the range of readings obtained, at the depths where the higher PID readings were recorded, a sample was taken from that interval for laboratory analyses of target compound list (TCL) and Resource Conservation and Recovery Act (RCRA) metal parameters. The data validation process indicates that the data are usable to make site decisions.

Only one compound ( methylene chloride ( exceeded a New Jersey Department of Environmental

Protection (NJDEP) action level. Specifically, the concentrations of methylene chloride exceeded the NJDEP impact to groundwater screening level at two locations ( B(6 and B(9.

Methylene chloride, however, is a very common laboratory artifact and is therefore not considered to be a site(specific constituent of concern.

Other volatile organic compounds (VOCs), semivolatile organic compounds (SVOCs), and metals were either not detected or their concentrations were below their respective NJDEP action levels. Polychlorinated biphenyls (PCBs) and pesticides were not detected in any of the samples analyzed during this investigation.

In conclusion, the PID readings and laboratory analyses of soil samples collected from borings B(

1 through B(13 indicate that there are no significant environmental concerns associated with soil at the boring locations.

SECTIONSECTIONSECTIONSECTIONONE INTRODUCTION

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1.1 GENERAL

This report presents the results of a geotechnical and a hazardous toxic radioactive waste

(HTRW) investigation performed by URS for the design of Segments B2 through B4 of the

Green Brook Flood Risk Management Project (GBFRMP). Field sampling for the investigation was conducted in July and August 2012. The line of protection of Segments B2 through B4 of the GBFRMP is located in the Borough of Middlesex, NJ (see Figure 1).

1.2 PROJECT OVERVIEW

The GBFRMP is divided into several segments. This report summarizes the results of the geotechnical and HTRW investigations for Segments B2 through B4 which lie in generally a north(south orientation along the west side of the stream Bound Brook. This information will be used in the design of line of protection structures. Segment B2 starts at the eastern end of

Segment B1 (approximately Sta. 29+00) which is currently under construction, and is followed by Segments B4 and then B3 (see Figure 2) (Segment B3 is located south of Segment B4), with the southern end of Segment B3 anticipated to end at approximately Sta. 59+50 and then tie back temporarily toward the Middlesex Library parking lot. The total length of Segments B2, B4 and

B3 will be about 3050 lineal feet (approximately ½ mile) excluding the temporary tie back to high ground. The northern terminus is located along Starlit Drive behind Lot 11 near the intersection with June Way and extends southward where it temporarily ties off to high ground along Mountain Avenue between the Middlesex Library and Borough Hall south of Legion

Place.

Based on preliminary design developed to date, the line of protection will consist of a flood wall from Sta. 29+00 to Sta. 52+20 (Bound Brook Road / Route 28), a closure gate across Bound

Brook Road (Sta. 52+20 to Sta. 53+80), and then a flood wall and a levee (Sta. 53+80 to Sta.

59+50) where the alignment turns to temporarily tie off in high ground near the library parking lot. Future plans not covered by this report include Segment B5 which will extend the line of protection further south to the upstream limit of the overall Segment B as it transitions into

Segment H. It should be noted that at the present time, the final limits of these segments have not yet been determined.

The line of protection will be designed for a 150(year flood elevation of between 48 and 49 feet

(NGVD 29) or approximately an average 48.5 feet (NGVD 29). Therefore, including the typical freeboard, the top elevation of the structure will be approximately elevation 52 ft (NGVD 29).

Considering the existing grade elevation along the alignment of flood walls, the height of the flood walls will likely to range from 12 ft to 17 ft. The proposed closure gate across Bound

Brook Road will be a roller gate type with a stem of approximately 12 to 13 feet high.

1.3 SCOPE OF INVESTIGATION

The primary objective of this investigation was to evaluate the geotechnical and HTRW subsurface conditions at the site for the preliminary design of the line of protection structures.

Thirteen geotechnical borings were conducted using a boring subcontractor and samples were taken for both geotechnical and HTRW evaluation by certified laboratories. URS staff provided

SECTIONSECTIONSECTIONSECTIONONE INTRODUCTION

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Radar (GPR) survey was conducted to assure that underground objects were avoided during the boring process and the GPR survey sketches are included in Appendix A. The following report is a culmination of those activities and provides insights for use by the designer.

1.4 REPORT ORGANIZATION

This report is divided into five sections. Section 1 above provides a general introduction and summary of the scope of the effort. Section 2 includes a description of the subsurface investigation and site characterization. Section 3 summarizes the results of the geotechnical investigation and includes a discussion of geotechnical recommendations for the proposed structures. Section 4 includes the results of the HTRW investigation and data validation.

Section 5 indicates the limitations associated with investigation results included in this report.

Figures and appendices are provided at the end of the text.

SECTIONSECTIONSECTIONSECTIONTWO SUBSURFACE INVESTIGATION AND SITE CHARACTERIZATION

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2.1 GENERAL

This section provides an overview of the geotechnical and HTRW subsurface investigation program and a generalized description of the subsurface conditions at this project site. Details are described in the following sections.

2.2 SUBSURFACE INVESTIGATION

2.2.1 Geotechnical Borings and HTRW Sampling

Thirteen (13) test borings, denoted as B(1 through B(13, were performed at the locations shown in Figures 2 through 7. Inspection of the test borings was performed on a continuous basis by

URS geotechnical engineer, Ms. Emma Gretina under the direction of Mr. Vaikunthan

Navaratnam, PE. Environmental screening and sampling was performed under the direction of

URS environmental scientist, Mr. Sunil Samaroo.

The borings were performed during the period from July 26, 2012 to August 6, 2012 by Craig

Test Boring, Inc. of Mays Landing, New Jersey using a CME(75 truck mount drill rig and a CME

55 ATV rubber track rig. The borings were performed using rotary drilling techniques with a 3(

7/8 inch diameter tri(cone roller bit and 4 inch. steel casing. Soil samples were obtained using techniques and equipment in general accordance with the American Society for Testing and

Materials (ASTM) Standard Specification D1586(Standard Penetration Test (SPT). The SPT consists of driving a 2 inch O.D. split spoon sampler for a distance of 24 inches, with repeated blows of a 140 lb. hammer free falling a distance of 30 inches. The standard penetration, or N( value, is determined as the number of blows required to advance the sampler 12 inches after the initial 6 inches of penetration. In order to obtain a larger volume of soil for laboratory testing, a

3 inch O.D. split spoon sampler was used in borings B(1 through B(3, B(9, B(12, and B(13. The split(spoon sampler was advanced using an automatic hammer for all soil samples obtained. SPT samples were obtained continuously for the first 10 ft and at regular intervals not exceeding 5 feet thereafter. The soil samples were visually classified by the URS field inspector using the

Unified Soil Classification System and placed in labeled sample jars.

In addition to the split(spoon samples, an undisturbed Shelby(tube sample of fine(grained soils was attempted on test boring B(2 at a depth of 2 feet. The recovery was only about 6 inches long and the sample was clayey sand and was determined not to be useful. Apart from this sample, fine(grained soils encountered at other locations were relatively stiff or not more than 2 feet in thickness. Therefore, no other Shelby(tube samples were obtained.

The soil in each sample was field screened for organic vapors at 6(inch intervals using a photoionization detector (PID). In each boring, environmental soil samples were either collected from above the water table or from a depth interval that showed the highest PID readings above background levels. Only background PID readings were observed in the majority of the borings with the exception of borings B(5 and B(10. These borings were associated with PID readings of

31 parts per million (ppm) and 350 ppm, respectively. Appendix B shows the PID readings and the depths from which soil samples were collected from each boring.

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At each boring, soil samples for volatile organic compounds (VOCs) analysis were collected first using three 5(gram EnCore samplers, as currently required by the New Jersey Department of

Environmental Protection (NJDEP). Soil samples were then collected using a disposal sampling scoop in the following order: semivolatile organic compounds (SVOCs), pesticides, polychlorinated biphenyls (PCBs), and Resource Conservation and Recovery Act (RCRA) metals. The sampling order was maintained to minimize loss of any volatile constituents during the sampling event.

Clean, dedicated sample bottles were supplied by the project laboratory and labeled with the date, time of sample collection, initials of sample collector, type of analysis requested, and unique sample number. The sample bottles were placed in coolers and packed with ice as a preservative to cool the samples to four (4) degrees centigrade. The samples and completed Chain(of(

Custody forms were picked up after each day of sampling by laboratory courier.

Rock coring was performed using a five(foot long NX (2(1/8 in. O.D.) core barrel. The top of rock was estimated based on the drilling operations (e.g., excessive rig chatter, difficult penetration) and practical spoon refusal as indicated by blow counts greater than 100 for a 6(in.

interval on the split spoon sampler. Rock coring was performed to verify the presence of rock, and to assess its relative quality as indicated by the Core Recovery and the Rock Quality

Designation (RQD)

The test boring logs are included in Appendix C.

2.2.2 Borehole Permeability Testing

Borehole permeability tests were conducted at depths of 5 and 10 ft below existing grade in

Borings B(2, B(5, B(8, B(11, and B(13 to better define the in situ soil permeability values for use in seepage analyses. The borehole permeability testing was performed using the falling head permeability test method. This method consists of drilling a borehole to the desired testing depth and installing casing to the bottom of the borehole. A few feet of gravel was then placed in the bottom of the borehole and the casing was lifted to the top of the test zone. The casing was then filled with water and allowed to saturate for 1 hour. Once the saturation was complete, measurements of the water level within the casing with time were made both manually using a groundwater level indicator, and electronically using a Levelogger® automatic water level recording device. Manual water level readings were generally recorded at 5 minute intervals, while Levelogger® readings were recorded at 1 minute intervals.

The results of the borehole permeability testing were then used to estimate the in situ soil permeability. Permeability testing data and permeability calculations are included in Appendix

D.

1 The Core Recovery is defined as the ratio (expressed as a percent) of the total length of recovered core to the length of the core run.

2 The Rock Quality Designation (RQD) is defined as the ratio (expressed as a percentage) of the total length of recovered core samples measuring at least twice the core diameter (e.g. 4 in. for NX(core) to the total length of core run.

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2.2.3 Geotechnical Laboratory Testing

Laboratory testing was performed on selected samples from the borings for the purpose of confirming the visual soil classification made in the field and to assist in engineering evaluations.

Tests on representative soil samples obtained from the borings were performed at the TerraSense

Laboratory located in Totowa, New Jersey. Table 2(1 presents a summary of the laboratory testing performed. Complete laboratory test results are included in Appendix E.

Table 2�1: Summary of Laboratory Tests Performed

Type of Test No of Tests

Sieve Analysis (ASTM D422) 23

Combined Sieve and Hydrometer Analysis (ASTM D422) 17

Atterberg Liquid Limit and Plastic Limits (ASTM D4318) 8

Natural Water Content (ASTM D2216) 21

Point Load Strength Index of Rock (ASTM D5731) 4

Unconfined Compressive Strength of Rock (ASTM D4543) 1

2.2.4 HTRW Laboratory Testing

Laboratory analyses were performed on selected soil samples. The samples were analyzed by

Accutest Laboratories of Dayton, New Jersey (New Jersey Lab No. 12129). Each soil sample was analyzed for target compound list (TCL) VOCs and a library search of the next 15 compounds (VOCs +15), TCL SVOCs +25, TCL pesticides, TCL PCBs, and RCRA metals.

RCRA metals consist of the following group of constituents:

• arsenic

• barium

• cadmium

• chromium

• lead

• mercury

• selenium

• silver

URS received the analytical reports in five Sample Delivery Groups. The data packages were provided in the New Jersey Reduced Deliverables Format. Chain of Custody forms are provided in Appendix G. The laboratory analytical data was provided to the NY USACE on CD under separate submission. A tabulated sampling and analysis summary of this investigation is provided in Table 2(2, below.

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Table 2�2: Summary of Environmental Soil Sampling Performed

Sample

Location

Sampling

Date

Sampling

Depth (ft bgs)

Soil

Sample

Type Lab ID

Chemical Analyses and Methods

B&1 8/2/2012 6.5&7.0 split spoon JB12748&1

B&2 8/2/2012 5.5&6.0 split spoon JB12748&3

B&3 8/2/2012 9.5&10.0 split spoon JB12748&2

B&4 7/27/2012 8.5&9.0 split spoon JB12318&3 TCL VOCs 8260B

B&5 7/26/2012 11.5&12.0 split spoon JB12188&1 TCL SVOCs 8270D

B&6 7/26/2012 9.5&10.0 split spoon JB12188&2 TCL Pesticides

8081B

B&7 7/26/2012 9.5&10.0 split spoon JB12188&3 TCL PCBs 8082A

B&8 7/26/2012 9.5&10.0 split spoon JB12188&4 RCRA Metals SW&

B&9 8/3/2012 9.0&9.5 split spoon JB12844&1

B&10 7/27/2012 8.0&8.5 split spoon JB12318&1

B&11 7/27/2012 8.5&9.0 split spoon JB12318&2

B&12 8/6/2012 6.5&7.0 split spoon JB13005&2

B&13 8/6/2012 4.5&5.0 split spoon JB13005&1

Notes

1. Split spoons used for sample collection were either the Standard Penetration test spilt spoon

(2&inch OD) or California Sampler (3&inch OD).

Legend Sample

Delivery ft bgs = feet below ground surface

Group

Reports

PCBs = Polychlorinated Biphenyls 1.) JB12188

RCRA = Resource Conservation and Recovery Act 2.) JB12318

SVOCs = Semivolatile Organic Compounds 3.) JB12748

TCL = Target Compound List 4.) JB12844

VOCs = Volatile Organic Compounds 5.) JB13005

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2.3 SITE CHARACTERIZATION

2.3.1 LOCAL GEOLOGY

The Green Brook area is located in a geological, structural, and topographic province known as the Piedmont Physiographic Province, which is underlain by rocks of the Newark Basin. The

Newark Basin consists of slightly folded and faulted, red(colored, sedimentary sandstones, siltstones, and shales of Triassic and Jurassic ages (about 200 million years ago) and dark igneous basalts and diabase of Jurassic age. The general topography of the area is characterized by a broad, southeastward sloping and gently rolling lowland.

The project area is at an elevation of about 30 to 40 ft and underlain by the Passaic Formation.

The Passaic Formation is a Lower Jurassic and Upper Triassic unit of the Brunswick Group consisting of grayish(red to reddish(brown, evenly to irregularly bedded, thin(to thick(bedded shale, siltstone, very fine to coarse(grained sandstone, and red(matrix conglomerate. The maximum thickness of the formation is about 19,000 feet. The depth to the underlying Passaic

Formation in the project area is about 30 feet. The overburden consists of fill, sand, and weathered rock. A detailed description of the overburden and rock units is provided below.

2.3.2 Generalized Subsurface Conditions

The generalized strata descriptions provided below are based on our interpretation of the results of the subsurface investigation. One generalized subsurface profile was prepared along the alignment and presented in Figure 8.

STRATUM 1: FILL

A fill stratum was encountered in borings B(4, B(9A, and B(10, and likely exists sporadically across the project area. The samples obtained from the borings indicate that this stratum consists of red(brown to green sand, with varying amounts of silt, gravel, organic material, and wood.

The thickness of this stratum, where encountered, was less than 5 feet. SPT N(values obtained within this stratum ranged from 5 blows per foot (bpf) to 34 bpf.

STRATUM 2: SAND

This stratum was encountered either at the ground surface, below Stratum 1, or below a thin layer of top soil. The material in this stratum generally consists of red(brown sand with varying amounts of silt, clay, and gravel. Thickness of this stratum varies from approximately 15 ft to over 30 feet. Borings B(3 through B(9B and B(11were terminated in this stratum. SPT N(values within this stratum ranged from 4 bpf to over 100 bpf, with typical values being between 5 and

25 bpf, indicative of a loose to medium dense material.

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STRATUM 3: COMPLETELY WEATHERED ROCK

This stratum was encountered in borings B(1, B(2, B(10, B(12, B(13. It consists of red(brown, completely weathered, very weak, siltstone. Thickness of this stratum varies from approximately

5 ft to over 10 feet. Borings B(2 and B12 were terminated in this stratum. The SPT N(values in this stratum were typically greater than 100 bpf, indicative of a very dense state of compactness.

STRATUM 4: BEDROCK

Bedrock was encountered in borings B(1, B(10, and B13. The core recovery ranged from 83 to

100 percent, and the RQD ranged from 0 to 10 percent. The bedrock consists of red(brown, slightly weathered, medium strong, highly fractured, siltstone. Based on borings B(1, B(10 and

B(13, it appears that top of bedrock elevation is approximately +2 ft at the northern end of

Segment B(2 and gradually slopes down to approximately elevation (1 ft until slightly south of

Bound Brook Road. The top of rock then slopes upward to approximately elevation +19 ft at the end of Segment B3. The anticipated bedrock profile as described above is presented in Figure 8.

2.3.3 Groundwater Conditions

Groundwater was measured within the boreholes prior to the introduction of drilling fluid or water. It is possible that these measurements may represent a “trapped” groundwater condition.

This occurs when groundwater becomes retained on top of a relatively low permeability layer. A summary of the groundwater observations are presented in Table 2(3, below. The groundwater measurements were not taken over an extended period of time; therefore, they do not reflect potential seasonal variations in the groundwater level.

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Table 2�3: Summary of Groundwater Observations

Date of

Groundwater

Observation

Borehole

Number

Ground

Surface

Elevation (ft)

Depth of

Groundwater from the ground surface (ft)

Groundwater

Elevation

(approximate)

(ft)

August 8, 2012 B(1 33.8 7 26.8

August 8, 2012 B(3 40.9 8 32.9

July 27, 2012 B(4 43.1 10 33.1

July 26, 2012 B(5 45.0 12 33.0

July 27, 2012 B(6 42.7 10 32.7

July 26, 2012 B(7 40.7 10 30.7

July 26, 2012 B(8 39.5 9 30.5

August 3, 2012 B(9B 37.3 10 27.3

July 27, 2012 B(10 39.5 10 29.5

August 6, 2012 B(12 36.0 6 30.0

SECTIONSECTIONSECTIONSECTIONTHREE RESULTS OF GEOTECHNICAL INVESTIGATION

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3.1 GENERAL

This section of the report provides a summary of the results of the geotechnical investigation and conceptual level geotechnical recommendations for the preliminary design of proposed structures. The conceptual level recommendations are based on the results of the field investigation performed for this project, our experience with similar projects and the current understanding of the proposed project requirements.

3.2 MATERIAL PARAMETERS

The primary geotechnical material parameters required for the global stability, foundation and seepage analyses are the shear strength, unit weight and permeability (hydraulic conductivity) of the foundation and fill (for levee) materials. The foundation soils overlying the bedrock are generally coarse to fine sand with trace to some silt, trace gravel and clay. Therefore, considering that overburden soils are generally cohesionless, effective stress shear strengths are presented in this section. The shear strength and unit weight values can be estimated using the laboratory shear strength tests and/or empirical correlations. As mentioned in Section 2.2.1, undisturbed tube samples were not obtained from the test borings, since the overburden soils were predominantly sandy soils. Therefore, shear strength and unit weight values were estimated using the standard empirical correlations based on the SPT N(Values obtained from test borings.

The estimated friction angle using standard empirical correlations ranges from 32 degrees to 34 degrees for the natural sandy soils (Stratum 2). Therefore, a conservative effective stress friction angle of 32 degrees is recommended for the natural sandy soils (Stratum 2). It should be noted that fill material (Stratum 1) was encountered only at isolated locations and as discussed in the following sections, any unsuitable fill material should be removed during the construction.

Based on the results of borehole permeability tests included in Appendix D, the permeability of the sandy (with fines content generally ranging from 10% to 35%) soils (Stratum 2) ranges from approximately 9 × 10 (4 cm/sec to 4 × 10 (5 cm/sec. It should be noted that these borehole permeability test results are consistent with typical permeability values for sandy soils with silt contents ranging from 10% to 35%.

Compacted fill materials should be used for the construction of the levee as discussed in Section

3.4.3. A summary of material (including compacted fill) properties is presented below in Table

3(1.

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Table 3�1: Summary of Material Parameter Values

Item

Friction angle

(degrees)

Cohesion

Intercept

(psf)

Total Unit

Weight

(pcf)

Coefficient of

Permeability (K)

(cm/sec)

Existing Fill (Stratum 1) 28 0 110 9 × 10 (4 to 4 × 10 (5

Sand (Stratum 2) 32 0 120 9 × 10 (4 to 4 × 10

Completely Weathered

Rock (Stratum 3) 38 0 135 10

Compacted Fill (Shell) 32 50 120 10 (4

Compacted Fill (Core and homogeneous levee) 32 50 120 10

(or less)

Based on the laboratory test results, the unconfined compressive strength of intact rock samples ranged from 694 to 9,360 psi, with an average of approximately 5,000 psi. However, considering the rock mass is highly fractured (i.e., borings B(1 and B(13 ( RQD = 0%, and B(10 – RQD =

10%) the compressive strength of the rock mass is typically only about 15% of the intact rock strength. Therefore, the recommended compressive strength of the shale rock mass at the project is 750 psi. Based on the laboratory test results, the recommended unit weight of shale rock is

160 pcf. An allowable bond strength (grout / rock interface frictional resistance) of 50 psi is recommended for the design of caissons socketed into rock.

3.3 SEISMIC CONSIDERATIONS

In accordance with the National Earthquake Hazards Reduction Program (NEHRP, 2009) seismic provisions, the recommended seismic site classification is Site Class “D”. Considering that the sandy soils below the groundwater level are generally medium dense to dense, earthquake induced liquefaction is not likely to be a concern at this site. However, it is recommended that a liquefaction analysis using the simplified Seed and Idriss method (with recent updates) be performed during the final design.

3.4 GEOTECHNICAL RECOMMENDATIONS

3.4.1 Flood Walls

It is our understanding that the height of the flood walls may range from 12 ft to 17 ft. Typically, when the height of the flood wall is greater than 10 ft, conventional reinforced concrete cantilevered walls (T(Wall) are considered instead of cantilevered sheet pile walls with concrete cap (I(Wall). At present the final heights of the flood walls are unknown, therefore, conceptual recommendations are given for both T(walls and I(Walls.

Foundations for T(Walls:

The footings for the T(walls can be founded on Stratum 2 and designed for a maximum allowable bearing pressure of 3 tsf. It should be noted that the final allowable bearing pressure will depend on the settlement estimates and tolerable settlements. However, considering the

I:\Projects\11020912(GB&SegmetB2&B3&Geotech)\Geotech&report\final report&GB&segments_11_19_12.doc 3(3 anticipated relatively large uplift and lateral loads, deep foundations are likely to be the most feasible foundation system instead of shallow foundations bearing on Stratum 2. Deep foundations can be either driven piles bearing on bedrock or drilled caissons socketed into bedrock. Considering that the depth to bedrock may range from 20 ft to 40 ft below the existing ground surface, the uplift capacity (on the order of 10 to 20 tons) of the piles driven to bedrock may not be sufficient especially at locations where bedrock may be encountered at a depth of 20 feet. In addition, at some locations the line of protection may become very close to existing residential buildings. Therefore, the vibrations due to pile driving and access of pile driving equipment rig may also become concerns.

Alternatively, although significantly more costly than driven piles, the T(Walls can be supported on drilled caissons socketed into bedrock. Depending on design loads, spacing, total cost and construction considerations; the drilled caissons can either be mini(caissons with nominal diameters ranging from 8 inches to 12 inches, or large diameter caissons ranging from 24 inches to 36 inches in diameter. Depending on the diameter and rock socket length, the allowable compression capacities of mini(caissons and large diameter caissons may range from 70 to 100 tons, and 120 to 300 tons; respectively. It should be noted that calculations for compression, uplift and lateral capacities should be performed.

Further, considering that foundation soils are sandy with varying amounts of silt, it will be very likely that a sheet pile cut(off will be required to control the under seepage and exit hydraulic gradients.

I(Walls:

Typically, I(walls are driven steel sheet pile walls with reinforced concrete cap above the ground surface. In addition, generally the required minimum embedment length of sheet piles below the existing ground surface may range from 2 ½ to 3 times the height of the flood wall. Therefore, considering that bedrock at some locations may be encountered at a depth of 20 ft below the ground surface, if the height of the I(wall exceeds about 5 ft to 8 ft, it may not be feasible to achieve the required minimum embedment. In such situations, a T(Wall or I(Wall with drilled in soldier piles and sheet pile lagging can be considered as alternative options. One of the advantages of the I(Wall is that a separate cutoff wall will not be required. However, vibrations due to sheet pile driving should be considered.

3.4.2 Closure Gate

It is our understanding that the closure gate across Route 28 (Bound Brook Road) will be a roller gate with a gate monolith and a closure monolith. The height of the stem will be approximately

12 to 13 feet high. The foundation recommendations provided in Section 3.4.1 for T(Wall are also applicable to support the closure gate structures such as gate monolith and a closure monolith.

3.4.3 Levee

It appears that towards the end of Segment B3, a portion of the line of protection will consist of a levee, with the height ranging from 12 ft to 15 ft above the existing ground surface. Based on

I:\Projects\11020912(GB&SegmetB2&B3&Geotech)\Geotech&report\final report&GB&segments_11_19_12.doc 3(4 our experience with similar projects, it is anticipated the levee will have a ten(foot wide top and

2.5H:1V side slopes. Based on test borings performed on the protected side of the line of protection, foundations soils are generally medium dense to dense sandy soils. Further, except for isolated pockets of soft and/or loose surficial soils (top soils) no distinct layer of soft compressible soils was encountered at the site. Therefore, deep(seated failure (global stability) of the levee will not likely to be a concern. However, stability analyses should be performed for all loading conditions in accordance with EM 1110(2(1913.

Since no soil borings were performed on the unprotected side, it should be anticipated that there may exist a thin layer of soft organic soils within this area. Any such unsuitable soils should be removed and replaced with approved compacted fill material, prior to levee construction. It is anticipated that most settlements will occur during the construction stage.

Further, considering that foundation soils are sandy with varying amounts of silt, it will be very likely that a sheet pile cut(off or a cut(off trench filled with compacted core material will be required to control the under seepage and exit hydraulic gradients. However, it should be noted that excavations for a cut(off trench may extend below the groundwater level.

The levee embankment and subgrade should be constructed in lifts and compacted as a homogeneous mass. The fill material should be placed in horizontal layers not more than 12 inches thick with each layer compacted to at least 95% of the maximum Modified Proctor density

(ASTM D1557). The fill should consist of mineral soil, free of organic matter, putrescibles, contamination, or other objectionable materials. It is recommended that the levee embankment and subgrade fill generally satisfy the following criteria:

• Maximum particle size: 6 inches

• Passing the No. 4 Sieve: Between 30% and 75%, by weight

• Passing the No. 200 Sieve: Between 15% and 40%, by weight

• Plasticity Index: Between 2 and 15

• Permeability: 1 × 10 (5 cm/sec or less for core of the levee or homogeneous levee

• Permeability: 1 × 10 (4 cm/sec or less for shell of the levee

However, it should be noted that final criteria for the fill material should be based on maximum permeability values and minimum shear strength values obtained during the final design of the levee.

SECTIONSECTIONSECTIONSECTIONFOUR RESULTS OF HTRW INVESTIGATION

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4.1 GENERAL

This section provides a summary of HTRW investigation results and data validation.

4.2 DATA VALIDATION AND VALIDATION RESULTS

Selected laboratory analyses were validated by URS chemists to confirm that the analytical data are of sufficient quality to be used for their intended purpose. For this investigation, the main analytical objective was to establish initial baseline chemical data for the boring locations. The validation work focused on samples collected from borings B(12 and B(13. Because of their proximately to the Middlesex Municipal Landfill, borings B(12 and B(13 had the highest potential for intersecting contaminated soils. The data validation memorandum is provided in

Appendix G. A data validation summary is provided in the table below.

In general, most of the data that required qualification were assigned a "UJ" qualifier, which indicates that the analyte was not detected above the reported sample quantitation limit. The reporting limit, however, is approximate so that the non(detect status is not definite; the analyte may be present.

Two data points were assigned a "NJ" qualifier, which was applied only to tentatively identified compounds (TICs). The NJ qualifier is applied when a specific compound is tentatively identified though the TIC library search.

One data point was assigned an “A” qualifier, which indicates that a TIC is likely a laboratory generated aldol(condensation product and not a site(related compound.

Table 4*1: Summary of Data Validation Qualifiers Applied to HTRW Data

Qualifier Description Analyte

Impact to

Data Quality

A Lab Artifact –aldol condensate SVOC TICs None

NJ

Presumptive evidence for compound and estimated concentration (TICs only)

VOC and SVOC TICs

None

UJ Estimated reporting limit VOCs, SVOCs, pesticides, metals Low

As summarized in the table above, the validation process did not reveal any major issues with data quality. The validation effort shows that the analytical data are usable to provide a basis for making decisions regarding soil in the area of investigation.

4.3 NJDEP ELECTRONIC DATA DELIVERABLES

The analytical sampling data collected during this investigation were compiled into the current

NJDEP Hazsite Electronic Data Deliverable (EDD) format. The NJDEP EDDs were provided to

USACE under a separate submission.

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4.4 ANALYTICAL RESULTS

This section presents a summary of current NJDEP soil cleanup standards and describes the analytical results of soil samples collected during this investigation.

The following NJDEP media standards and criteria are relevant to this investigation:

• Soil: NJDEP Soil Remediation Standards (SRS), N.J.A.C. 7:26D, May 7, 2012

• Soil: NJDEP Default Impact to Groundwater (IGW) Soil Screening Levels, Revised

December 2008

The analytical data were compared to three sets of NJDEP soil action levels ( the residential standard, the non(residential standard, and the impact to groundwater screening level (Table 4.2 and Appendix H). The residential and non(residential standards are human health standards and are used to monitor compliance in residential and industrial settings, respectively. The impact to groundwater screening levels are used to assess the potential for soil to leach contamination into the groundwater. As described below, the concentrations of constituents found in soil did not exceed any human health standard.

Thirteen soil samples (B(1 through B(13) were collected from thirteen boring locations in the area of the investigation. Appendix H presents the analytical results for these samples. A summary of results that exceed SRS or impact to groundwater screening levels (IGWSL) is provided in the table below.

Table 4*2: Summary of Soil Exceedances of NJDEP Standards

Compound

NJ Residential

Direct Contact

Soil

(NJAC 7:26D)

NJ Non�

Residential

Direct Contact

Soil (NJAC 7:26D)

NJ Default

Impact to

Groundwater

Soil Screening

B�6

9.5�10 ft

B�9

9�9.5 ft

Methylene

Chloride 34 97 0.007

0.0074

0.0071

Concentrations in milligrams per kilogram (mg/kg)

The only constituent that was detected at concentrations above any NJDEP action level was methylene chloride. Methylene chloride was detected at concentration of 0.0074 milligram/kilogram (mg/kg) and 0.0071 mg/kg in samples B(6 and B(9, respectively, above the

IGWSL of 0.007 mg/kg.

Other VOCs, such as acetone, carbon disulfide, ethylbenzene, toluene, and xylene were detected, but their concentrations were below their respective SRS and IGWSLs. Several SVOCs, including benzo(a)anthracene, benzo(a)pyrene benzo(b)fluoranthene, and chrysene, were also detected but at concentrations below their respective SRS and IGWSLs (Appendix H). VOC and

SVOC tentatively identified compounds (TICs) were detected in several samples but their concentrations were not abnormally high (up to an estimated 125 mg/kg in VOC sample B(5).

Therefore, TICs are not considered to be constituents of concern at the boring locations.

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Pesticides and PCBs were not detected in any of the samples analyzed.

Arsenic, barium, chromium, lead and mercury were detected in every sample, but at concentrations but below their respective SRS and IGWSL (Appendix H).

In summary, only one compound ( methylene chloride ( exceeded a NJDEP action level.

Specifically, the concentrations of methylene chloride exceeded the NJDEP impact to groundwater screening level at two locations ( B(6 and B(9. Methylene chloride, however, is a very common laboratory artifact and is therefore not considered to be a site(specific constituent of concern.