W912P6-15-R-0006-McCookRockwallSlopeStabilizationIDIQ-00-31-32_Appendix_B_Geotechnical_Data_Report_(GDR)-VOL1.pdf

US Army Corps of Engineers®

CHICAGO DISTRICT

LEADERS IN CUSTOMER CARE

CONTRACT NO. W912P6-15-R-0006

CHICAGOLAND UNDERFLOW PLAN (CUP)

McCOOK RESERVOIR

ROCK WALL AND OVERBURDEN

STABILIZATION IDIQ

GEOTECHNICAL DATA REPORT (GDR)

7 JANUARY 2015

00 31 32 Appendix B

Chicagoland Underflow Plan (CUP) McCook Reservoir Rock Wall and Overburden Slope Stabilization IDIQ Geotechnical Data Report (GDR)

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Chicagoland Underflow Plan (CUP) McCook

Rock Wall and Overburden Slope Stabilizaiton

IDIQ

Table of Contents

List of Acronyms ............................................................................................................................. i

1.0 Introduction...................................................................................................................... 1-1

1.1 Purpose and Scope of the GDR..................................................................................... 1-1

1.2 Project Description ........................................................................................................ 1-1

1.3 Elevation Datum and Horizontal Control...................................................................... 1-3

1.4 Limitations .................................................................................................................... 1-3

2.0 Site Setting, Geology and Hydrogeology ........................................................................ 2-1

2.1 General .......................................................................................................................... 2-1

2.2 Regional Geology.......................................................................................................... 2-1

2.3 Project Site Geology...................................................................................................... 2-2

2.4 Geologic Formations ..................................................................................................... 2-3

2.4.1 Racine Formation................................................................................................... 2-3

2.4.2 Sugar Run Formation ............................................................................................. 2-3

2.4.3 Joliet Formation ..................................................................................................... 2-3

2.4.4 Kankakee Formation .............................................................................................. 2-4

2.4.5 Elwood Formation ................................................................................................. 2-4

2.4.6 Wilhelmi Formation............................................................................................... 2-4

2.4.7 Brainard Formation ................................................................................................ 2-4

2.4.8 Fort Atkinson Formation........................................................................................ 2-5

2.5 Regional Hydrogeology ................................................................................................ 2-5

3.0 Main Tunnel System Field Investigation Summary (AECOM 2008) ............................. 3-1

3.1 Field Investigation......................................................................................................... 3-1

3.2 Laboratory Testing ........................................................................................................ 3-2

4.0 Available Geological and Geotechnical Data .................................................................. 4-1

4.1 Harza Engineering (1971-1976) .................................................................................... 4-7

4.2 Army Corps of Engineers (1991) .................................................................................. 4-7

4.3 Golder Associates (1992) .............................................................................................. 4-7

4.4 STS Consultants (1996) ................................................................................................ 4-8

4.5 Patrick Engineering (1998) ........................................................................................... 4-8

4.6 De Leuw, Cather & Company (1999) ........................................................................... 4-9

4.7 URS (2000) ................................................................................................................... 4-9

4.8 Other Investigations – TSC, SCS (1980-1990) ........................................................... 4-10

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5.0 Project Ground Conditions .............................................................................................. 5-1

5.1 Soil ................................................................................................................................ 5-5

5.1.1 Fill .......................................................................................................................... 5-6

5.1.2 Natural Soils........................................................................................................... 5-6

5.2 Rock .............................................................................................................................. 5-6

5.2.1 Racine Formation................................................................................................... 5-6

5.2.2 Sugar Run Formation ............................................................................................. 5-7

5.2.3 Joliet Formation ..................................................................................................... 5-7

5.2.4 Kankakee Formation .............................................................................................. 5-7

5.2.5 Elwood Formation ................................................................................................. 5-8

5.2.6 Wilhelmi Formation............................................................................................... 5-8

5.2.7 Maquoketa Formation ............................................................................................ 5-8

5.3 Rock Structure and Quality ......................................................................................... 5-10

5.3.1 Bedding ................................................................................................................ 5-10

5.3.2 Rock Joints........................................................................................................... 5-10

5.3.3 Rock Quality Designation (RQD)........................................................................ 5-11

5.3.4 In Situ Stresses ..................................................................................................... 5-11

5.4 Groundwater................................................................................................................ 5-15

6.0 Previous Underground Experience in the Area ............................................................... 6-1

7.0 References........................................................................................................................ 7-1

Tables Table 4.1 Geotechnical Investigation Report Summary .............................................................. 4-2 Table 5.1 Drilling Program Summary ......................................................................................... 5-2 Table 5.2 Summary of Soil Engineering Properties (USACE, 2009).......................................... 5-5 Table 5.3 Summary of Engineering Rock Properties .................................................................. 5-9 Table 5.4 Summary of Dilatometer Test Results (URS, 2001) ................................................. 5-14 Table 5.5 Groundwater Elevation Summary ............................................................................. 5-15 Table 6.1 Previous Underground Experience in the Area ........................................................... 6-1

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Appendices

Figure 1 Generalized Stratigraphic Column of Site Geology Figure 2 Vicinity Map / Site Area Map Figure 3 Exploratory Borehole Location Plan / Project Site Area Map Figure 4 Geotechnical / Geological Profile

Appendix A Project Specific Lab Data Summary and Boring Logs Appendix B Historical Boring Logs Appendix C Historical Laboratory Data Summary Appendix D Scatter Plots – Rock Engineering Properties Appendix E Laboratory and In Situ testing Data (Raw) Appendix F In Situ Stress Test Data Appendix G Main Gate/Access Shaft Geologic Log and Groundwater Inflow Data i

List of Acronyms

ASTM American Society of Testing and Materials

BTS Brazilian tensile strength

CCD Chicago City Datum

CUP Chicagoland Underflow Plan

CSO combined sewer overflow

DDR Design Documentation Report

GBR Geotechnical Baseline Report

GDR Geotechnical Data Report gpm gallons per minute

HPU hydraulic power unit

ID inside diameter

LASMA Lawndale Avenue Solids Management Area

MGS Main Gate/Access Shaft

MTS Main Tunnel System

NAD 83 North American Datum of 1983 pcf pounds per cubic foot

PLI Point Load Index psi pounds per square inch

RQD Rock Quality Designation

SPT Standard penetration test

SWRP Stickney Water Reclamation Plant

TARP Tunnel and Reservoir Plan

TBM tunnel boring machinet ii tsf tons per square foot

UCS unconfined compressive strength

USACE United States Army Corps of Engineers

USCS Unified Soil Classification System

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1.0 Introduction

1.1 Purpose and Scope of the GDR

The purpose of the Geotechnical Data Report (GDR) is to document field and laboratory studies conducted for the project, and to tabulate and summarize the factual geological and geotechnical data available from the project-specific investigation and available data from previously completed investigations and studies. The data will aid in identifying potential geotechnical hazards, determining ground conditions, characterizing soil and rock mass characteristics, establishing baseline conditions and evaluating methods of construction. The report includes data from twenty previous subsurface geotechnical and hydrogeological investigations between 1971 and 2009, within the McCook Reservoir and Main Tunnel System (MTS) vicinity. These investigations comprised exploratory drilling and in-situ testing, followed by field and laboratory testing. This report summarizes the field data collected, presents the results of the laboratory tests performed, and reviews geological and historical literature pertaining to the site.

The investigation performed by AECOM (July 2008), for the McCook Reservoir MTS, was requested by the US Army Corps of Engineers (USACE), Chicago District in order to identify the geotechnical constraints associated with the design and construction of the proposed tunnel and shafts associated with the MTS.

The information presented in this Report consists of:

An overview of the project.

A description of the regional and project site geology.

A description of laboratory and field tests.

A summary of the geotechnical investigations undertaken at the site.

A description of the ground conditions based upon the laboratory and field testing investigations.

A summary of previous underground construction experience near the project site.

Interpretation of the factual data presented in the GDR is included in a separate document referred to as the Geotechnical Baseline Report (GBR). This GDR applies solely to the McCook Reservoir Site.

1.2 Project Description

Originally authorized in the Water Resources Development Act of 1999, the Chicago Underflow Plan (CUP) McCook Reservoir Project is a key component of Chicago’s ongoing Tunnel and

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Reservoir Plan (TARP), providing approximately 10 billion gallons of additional combined sewer overflow (CSO) storage to the Metropolitan Water Reclamation District of Greater Chicago’s (MWRDGC) network. To minimize flood damages (during periods of peak flow) to the City of Chicago and 36 surrounding suburban communities, the reservoir will store excess CSO water from the TARP Mainstream and Des Plaines Deep Tunnel systems until the floodwater levels recede. This stored CSO will be pumped to Stickney Water Reclamation Plant (SWRP) for treatment and appropriate discharge to the TARP network.

1.3 Elevation Datum and Horizontal Control

For the purposes of this report, all boring locations previously surveyed have been converted to State Plane NAD83 and Chicago City Datum, 1928 (CCD), to portray horizontal and vertical references. Some records in this GDR used prior reference data and no correlation has been made to the original records contained herein; however, the analysis of the GBR was made after considering the relative reference data of information used.

1.4 Limitations

This report is part of the Contract Documents and has been prepared for the exclusive use of the USACE as it relates to design and construction of the McCook Reservoir Final Reservoir Preparation. The report has been prepared in accordance with generally accepted engineering practice.

The Contractor must undertake his own independent review of the entire Contract Documents and other available data to arrive at decisions concerning planning the work, and the means, methods, techniques, sequences and procedures of construction for accomplishing the work.

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2.0 Site Setting, Geology and Hydrogeology

2.1 General

The site is located at the District's Lawndale Avenue Solids Management Area (LASMA), beneath the Stephenson (I-55) Expressway and beneath the MWRDGC Stickney Pumping Station in Willow Springs and McCook, Illinois. The site is within Lyons Township in western Cook County. Access to the site is via LaGrange Road, River Road and West Lawndale Avenue.

Immediately south of the site across Lawndale Avenue is a building housing a natural gas facility.

Surface relief across the working site is minimal, ranging from approximately elevation 12.0 CCD at the McCook Reservoir to approximately El. 21.3 CCD near the connection with the Mainstream Tunnel.

2.2 Regional Geology

Parts of the project area are covered by a relatively thin layer of man-made fill overlying natural materials. The project area is underlain by alluvium and glacial drift, in turn underlain by about 4,000 ft of sedimentary rocks ranging in age from Cambrian to Silurian. The sedimentary rock is underlain by Precambrian granitic rock.

The Chicago region lies on the eastern flank the Kankakee Arch. The Kankakee Arch trends northwestward across Indiana and Illinois, connecting the Cincinnati Arch with the Wisconsin Arch. The Silurian age bedrock strata dip gently eastward at about 15 ft per mile, and have an uneven top of rock surface dissected by Pleistocene age valleys and ridges. The Silurian bedrock is covered with a relatively thin mantle of glacial tills and valley fill sediments.

The bedrock surface is an undulating plain with valleys incised by glacial and pre-glacial erosion. These bedrock valleys are as much as 150 ft deep. The deeper, steep sided valleys were possibly incised during the retreat of the Illinoisan continental glaciers, however there is no evidence, from the investigations performed at the McCook site, of an incised valley on or near the project site. It is estimated that 100 ft or more of the bedrock surface was eroded by glacial abrasion. The bedrock surface in the Chicago area is relatively fresh and unweathered. The uppermost part of the bedrock surface is generally fractured and the frequency of fracturing decreases with depth. Some fractures have been enlarged by solutioning and some vuggy porosity is present.

The sedimentary rocks of the Silurian age, the Maquoketa, and other strata overlying the Precambrian, were deposited in generally shallow seas that advanced and retreated across the

2-2 interior of North America some 300-500 million years ago. Due to large scale tectonic events along the eastern continental margin, occasional uplifts caused midwestern sediments to be raised above sea level, exposed to erosion, and buried under deposits from advancing seas. These uplifts produced stratigraphic breaks, or unconformities, in the sedimentary rock sequence.

Unconformities are often characterized by irregular contacts between formations. The uneven Chicago bedrock topography is an erosional surface truncating the Kankakee Arch. The varying thicknesses of the Wilhelmi and Brainard Formations in the project area are due to the unconformity that separates the Silurian from Ordovician age strata.

The project site is located at the eastern end of a bedrock high that may be associated with one of these east/west trending folds which are superimposed on the regional dip of the Kankakee Arch.

These folds are broad and have amplitudes of about 200 ft over distances of several miles. The Paleozoic strata dip 10 to 15 ft per mile eastward toward the Michigan basin and may also vary near reef structures. Locally the folded units may dip up to 100 ft per mile.

Two major fault zones are recognized in the Chicago region; the Sandwich Fault Zone and the Des Plaines Disturbance. The Sandwich Fault Zone, located southwest of Joliet and approximately 30 miles southwest of the proposed Reservoir, consists of a northwest-southeast oriented fault with a vertical offset possibly more than 100 ft. The Des Plaines Disturbance, located northeast of O’Hare Field on the Des Plaines River (approximately 10 miles north of the proposed Reservoir), is an approximately circular area of internal faulting about 5.5 miles in diameter interpreted to be a impact feature. Numerous nearly vertical faults with vertical displacements of up to 600 ft expose older (Ordovician) rocks near the surface. Faulting within the Chicago area is rare, with the exception of those areas mentioned above. The few widely spaced faults in the project area are thought to have larger components of strike slip, rather than vertical offset, and generally trend northwest.

2.3 Project Site Geology

The site is located on a layer of surficial deposits comprising of fill material (presumably associated with ongoing dredging activities), poorly sorted recent alluvium, and lacustrine deposits from a prehistoric Pleistocene lake (Lake Chicago). This lake was formed when glacial meltwater became impounded, reaching depths of up to 150 ft in places. As the glaciers retreated this lake eventually broke lose depositing several clay, silt, sand and some gravel horizons.

Underlying these deposits is a series of massive, relatively homogenous Silurian and late Ordovician dolomites, including less prevalent interbedded shales formed during the early stages of diagenisis during this time. These rocks are a relatively uniform, approximately 300 ft thick, 2-3 sequence across the site and incorporate the Racine Formation, Sugar Run Formation, Juliet Formation, Kankakee Formation, Elwood Formation, and Wilhelmi Formation.

With the exception of the Des Plaines Disturbance (a probable meteorite impact zone) centered approximately 10 miles to the north, and some small, deep localized areas of possible seismic activity located to the south east, there are no significant fault traces noted within Cook County.

None of these faults are currently active and the seismic risk to the site is considered very low. A minor (magnitude 3.2) seismic event was experienced by the area with an epicenter located within 5 miles of the site in November 2013, and there were no impacts at the site aside from minor vibrations.

2.4 Geologic Formations

The bedrock geologic Formations (youngest to oldest) present at the project site are described below.

2.4.1 Racine Formation

The Racine Formation (Silurian System) consists of dolomite with zones of highly cherty strata in the middle and at the base of the formation.

During the Racine deposition, the Chicago area was occupied by a large complex of coral reef several miles in diameter. Three varieties, or facies, of the Racine are recognized as reef, reef-flank, and inter-reef facies (deposited during intervals between reef building periods). Some zones within the Racine display thin alternating layers of the reef and inter-reef facies within a short vertical distance, lenticular to continuous cherty horizons, and occasional solution pockets filled with clay and brecciated dolomite.

2.4.2 Sugar Run Formation

The Sugar Run Formation was named in 1973 by the Illinois State Geological Survey, six years after the initial subsurface exploration program for TARP and does not appear on early logs. It is designated as a well-bedded dolomite compromising what was formerly the basal 25 ft of the Racine Formation. The unit is lithologically similar to many inter-reef deposits, and although readily observed in outcroppings in the Chicago area, it is difficult to identify in cores. The early logs were reviewed, and, where possible, the Sugar Run Formation was identified.

2.4.3 Joliet Formation

The Joliet formation is divided into the Romeo and Markgraf members. The Romeo Member is a persistent, fairly uniform, pure, white to cream, very dense, very fine grained dolomite about 14 ft in thickness, underlies the Sugar Run Formation, and grades downward into the Markgraf member. Where exposed, the Romeo Member is locally mottled pink, exhibiting poorly developed thick bedding. The Markgraf member is a widespread, distinctively light bluish gray

2-4 dolomitic unit, underlying the Romeo Member. The Markgraf member consists of an upper zone which is fine grained, dense, containing a few, thin, clustered shale partings and soft, porous chert nodules; a middle argillaceous zone; and a silty lower zone in which closely spaced dolomitic shale laminae becomes increasingly common. The upper contact is defined as the uppermost cluster of shale partings.

2.4.4 Kankakee Formation

The Kankakee Formation generally has wavy beds of fine to medium grained, greenish gray, locally pinkish, dolomite layers, 1 to 3 in. thick. The bedding is often separated by numerous thin wavy partings of green shale. The upper contact is marked by thin laminae of bright green shale that occurs on a distinctive smooth, but deeply pitted surface.

2.4.5 Elwood Formation

The Elwood and Wilhelmi Formations are the oldest units of the Silurian System, formerly known collectively as the Edgewood formation. Their thickness varies widely because these were deposited on the underlying erosional surface developed on the top of the Maquoketa Group (generally the Brainard Shale).

The Elwood is a light gray to gray and fine to medium grained dolomite slightly argillaceous in the upper 30 ft and often very cherty. The chert occurs in the form of interbeds and nodules to

0.3 ft thick at an average spacing of 1 ft and is white, soft and porous. The Elwood upper contact is marked by a highly fossiliferous and vuggy zone below the bottom of the Kankakee Formation within the highly cherty zone. The Elwood can be seen in the sump pit area of the Vulcan Quarry, and has a tendency to form water seeps into the sump pit. The Elwood has demonstrated high hydraulic conductivities in borings throughout the project area, which may be due to secondary porosity caused by dissolution along the formation top.

The Elwood Formation has demonstrated a tendency to spall along bedding planes when exposed in the crowns of excavations constructed during previous work on the project. During portions of the excavation of Tunnel C in the Distribution Tunnels contract rockfall consisting of blocks of up to approximately 10-pounds from the crown of the tunnel necessitated a sequence of construction consisting of:

1. Drill and shoot a round of closely-spaced shot holes 8 to 12 feet deep

2. Remove shot rock/muck

3. Scale rock surface with high pressure air and pry bars

4. Apply 2-inches of fiber-reinforced shotcrete

5. Repeat steps 1-4

6. Install permanent rock support one round behind the working face as the heading proceeded.

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2.4.6 Wilhelmi Formation

The lower portion of the Silurian Series is called the Wilhelmi Formation which is a slightly cherty dolomite unit underlain by an increasingly very argillaceous, non-cherty dolomite unit.

The upper portion of the Wilhelmi is known is known as the Birds Member. Within the Birds, chert nodules decrease in frequency and size with depth, but become harder. Conversely, the argillaceous content and frequency and thickness of shale and dolomitic shale partings increase with depth through the formation. The lowermost portion of the Wilhelmi is formed from reworked Brainard Formation sediments and is identified as the Schweizer Member. The Schweizer consists of dolomitic shale with a basal layer of dolomitic siltstone, and containing brownish-black pebbles in a dolomitic shale matrix. Laminated, crinkled beds mark the base of the Schweizer.

The same properties exhibited by the Elwood Formation were encountered in excavating Tunnel C through the Wilhelmi Formation, and the same excavation sequence was used to mitigate rockfall concerns.

2.4.7 Brainard Formation (Ordovician Maquoketa Group)

The Brainard Formation of the Ordovician-Maquoketa Group (indicated on some drawings as “Top of Maquoketa”) is a dark greenish-gray, thin bedded, fossiliferous, silty claystone to shale with interbedded dolomite. The upper contact is sharp and slightly irregular with relief in the range of inches. As a result of erosion prior to deposition of the Wilhelmi, it varies in thickness from 1 ft to 136 ft. across Illinois, depending on the configuration of the Brainard-Wilhelmi unconformity. In the project area, the formation is less than 10 ft thick and averages approximately 4.5 ft thick – thinner in the area of the Tunnel D rock plug.

The Brainard Shale has been known to cause serious problems of slaking in underground excavations in Northern Illinois. During excavation of the TARP tunnels and mainstream Pump Station chambers, this problem was avoided by application of shotcrete within 48 hours after excavation. Where uncovered and exposed to water and air after excavation it deteriorated to mud resulting in over excavation to a depth of up to three feet in the invert of Tunnel C during the Distribution Tunnels project.

2.4.8 Fort Atkinson Formation (Ordovician Maquoketa Group)

The Fort Atkinson is an inter-bedded green shale and dolomite. The dolomite is medium grained, hard, crystalline, light gray, and slightly argillaceous. The shale p o r t i o n s o f t h e f o r m a t i o n a r e moderately soft, green, and occur as partings and bands to 0.1 ft thick.

Figure 1 (USACE, 2009) provides a generalized stratigraphic section of the site geology.

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2.5 Regional Hydrogeology

Regionally, groundwater is encountered in the unconsolidated glacial deposits and in the underlying Silurian dolomite bedrock in the Chicago area. Although water supplies have been developed within these two upper hydrostratigraphic units, they are not considered major aquifers. The limited bedrock supply is primarily contained within the joints and bedding planes.

The Maquoketa shale forms a regional confining layer separating the Silurian dolomites from the underlying Ordovician units. Consequently, groundwater flow and quality within the upper dolomites (Silurian formations) differs from that found in the deeper sandstone formations.

The major aquifer/aquitard systems identified in the Chicago area include the following:

1. Glacial drift deposits (where sufficient deposit thickness and yields occur). Glacial deposits tend to be thin, with no significant water-bearing units in the project area.

2. Upper bedrock aquifers (Silurian dolomites). Generally not considered significant in the project area, with water limited to joints and bedding planes.

3. Upper Ordovician aquitards (Maquoketa Shale and Galena and Plattesville dolomites).

Not encountered within the tunnel horizon or shafts for this project.

4. Lower sandstone aquifers (Ordovician-St. Peter and Cambrian Ironton-Galesville sandstones). Not encountered within the tunnel horizon or shafts for this project.

2.6 Local Hydrogeology

Numerous open-pit rock quarries, such as the McCook Quarry have been excavated into the Silurian dolomite bedrock in the Chicago area – including the reservoir itself. These quarries may extend to the top of the Maquoketa Shale, approximately 300 ft to 350 ft below the ground surface. Dewatering systems are required to keep the quarry bottom dry during operations.

The dewatering operations have lowered water levels in surrounding bedrock and created a regional cone of depression within the dolomite. Groundwater flow within the upper bedrock aquifer is likely to have changed flow directions and hydraulic gradients over time, as existing quarries were excavated deeper and new quarries began operations in other areas (URS, 2001.)

Ongoing dewatering associated with the Vulcan Materials McCook Quarry, the Hanson Materials Service “Federal Quarry” and the McCook Reservoir excavation have resulted in a locally depressed piezometric surface within the bedrock. The site location between two surface waterways has impacted the near-surface hydrogeology and necessitated the construction of an overburden cutoff wall (slurry wall) around the reservoir. Construction of the McCook Reservoir

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Grout Curtain has also altered the groundwater characteristics at the site and has significantly reduced groundwater and surface water inflow and infiltration into the reservoir.

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3.0 Main Tunnel System Field Investigation Summary (AECOM

2008)

In July 2008 the USACE, Chicago District contracted with AECOM to complete a geologic investigation for the proposed McCook Reservoir Main Tunnel System to supplement the existing available subsurface data described in Section 4.0. The geologic investigation was conducted to determine the geology, geotechnical and aquifer characteristics along the Main Tunnel System alignment between the Mainstream Tunnel System and McCook Reservoir. A summary of the geotechnical investigation, from AECOM’s 2008 report is provided below.

Refer to Appendix A for the AECOM investigation boring logs.

3.1 Field Investigation

The three borings (LB-121-08, LB122-08 and LB-123-08) were completed by an AECOM drill crew using a Dietrich D-25 truck-mounted rotary drill rig. A map of the approximate project site location, the soil boring locations, and geological/geotechnical profile are shown on Figures 2 through 4.

The borings were typically advanced using power auger and rotary wash methods through the overburden soil until the top of bedrock was reached. Soil samples were obtained using split-spoon sampling techniques in accordance with American Society of Testing and Materials (ASTM) Standard D-1586. Samples were collected at 2.5 ft intervals until bedrock was reached.

Once the top of the bedrock had been reached, the rock was cored with an HQ sized bit in approximately 10 ft runs. Point load testing was performed in the field shortly after the cores were retrieved. The cores were labeled, placed into wooden core boxes, and photographed.

When boring LB-121-08, was drilled near the top of bedrock, several boulders were encountered that misaligned the casing; the hole location was offset approximately 5 ft, and the casing redrilled to approximately 2 ft into the bedrock.

At boring completion, packer testing was conducted using dual packers at approximate intervals of 20 ft. The boring at the MGS location (LB-121-08) was packer tested from 51 ft to 371 ft below ground surface, while borings LB-122-08 and LB-123-08 were packer tested between approximately 215 to 315 ft below the ground surface.

Following packer test completion, borehole geophysical logging was performed. AECOM subcontracted the geophysical evaluation to Geological Logging Systems, Bluefield, Virginia.

The geophysical evaluation was performed to characterize borehole temperature, water flow, gamma density, neutron density, and sonic measurements.

3-2

After completion of the three main borings, two additional soil borings were drilled to collect undisturbed Shelby tube samples for laboratory testing. Three Shelby tubes were obtained;

however, at the lab it was found none of the recovered material was suitable for testing as the samples were either too soft, overly disturbed, or contained excessive granular material.

Once the geophysical evaluation was completed, the borings were tremie grouted to the ground surface using a portland cement grout, and the surface repaired with asphalt patching material.

The two soil borings drilled to collect Shelby tube samples were backfilled with bentonite chips, concreted and patched with asphalt.

Field logs and well installation diagrams were prepared as the drilling progressed, by an AECOM field geologist, and are in general conformance with “The Standard Guide for Field Logging Subsurface Exploration of Soil and Rock – ASTM D 5434”.

3.2 Laboratory Testing

In addition to point load testing performed in the field, laboratory tests were completed on selected rock and soil samples to characterize physical properties of soils and rock encountered in borings. The unconfined compressive strength (UCS) of selected cohesive soil samples was estimated using a calibrated penetrometer. The penetrometer values are shown on the individual boring logs. In conjunction with the laboratory testing program, the majority of the soil samples were classified on the basis of texture and plasticity in accordance with the AECOM Soil Classification System. These descriptions and estimated group symbols are in general conformance with the Unified Soil Classification System (USCS), and are included on the soil boring logs. The following laboratory tests were performed on borings LB-121-08, LB-122-08, and LB-123-08, and the tabulated summary of results are presented in Appendix A.

Soil:

Particle Size Analysis Specific Gravity Moisture Content Atterberg Limits

Rock:

Packer Testing Unit Weight and Porosity Brazilian Tensile Strength (BTS)

Unconfined Compressive Strength (UCS) Direct Shear (pre-sawn)

3-3

Direct Shear (existing) Triaxial Creep Slake Durability Swelling Strain

4-1

4.0 Available Geological and Geotechnical Data

Since the early 1970’s, twenty subsurface geotechnical and hydrogeological investigations have been performed with respect to construction of the proposed McCook Reservoir and Main Tunnel System. The source of historical investigation information used in preparation of this GDR is the DDR for the Chicago Underflow Plan, Chicago, Illinois Vol. II of VIII dated November, 1999 (prepared by the USACE, Chicago District), and the Groundwater Protection System Design Documentation Report for the Chicagoland Underflow Plan, Chicago, Illinois Vol. I dated August 2006 (prepared by the USACE, Chicago Illinois). The details of these investigations are summarized in Table 4.1 below and in the proceeding text.

Refer to Appendix B (CD provided in front sleeve of binder) for a summary of the included historical borings logs, location map, and the boring logs arranged by investigation title.

Refer to Appendix C for a summary of historical laboratory test results, and Appendix D for scatter plots of the rock engineering properties, Appendix E for the raw laboratory and in situ testing data, and Appendix F for the in situ stress test data.

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Chicagoland Underflow Plan (CUP) McCook Reservoir Final Reservoir Preparation

4-7

4.1 Harza Engineering (1971-1976)

The Hodgkins Pump Station, located between the Des Plaines River and the Vulcan Quarry, was investigated by Harza Engineering under contract to the MWRDGC in 1976, the Mainstream Tunnel System, Contract 73-162-2H-Part 1. This investigation consisted of soil and rock borings necessary for the design of the buildings, shafts and chambers, and tunnels located at the pump station. The study conducted UCS tests (Appendix E) as part of the investigation. In addition, borings relevant to the project area have been referenced from work performed in 1972 for the design of the tunnel systems under the North Side Rock Tunnel Project contract. Harza conducted BTS, UCS, and RQD tests under this contract. Harza also conducted investigations BTS and RQD tests between 1974 and 1975 for the Tunnel and Reservoir Plan Mainstream System project (Appendix B). Harza performed a hydrogeologic investigation in October 1983, for the MWRDGC and the purpose of the investigation was to determine the hydraulic properties of various rock strata in the project area. Refer to Appendix C for a summary of the laboratory test data, Appendix D for histograms of the rock engineering properties and Appendix E for the raw laboratory data. See report numbers 1, 2, and 3 in Tables 4.1 and 5.1 for additional information.

4.2 Army Corps of Engineers (1991)

The U.S. Army Corps of Engineers, Nashville District, in November 1991 performed a subsurface investigation to determine the engineering properties of rock in the areas of the proposed underground and hydraulic structures and the investigations were contracted to Golder Associates under the COE/GRNDWTR/IL contract. The boring locations for this investigation were based on the reservoir being at the Vulcan Quarry. The U.S. Army Corps of Engineers, Ohio River Division Laboratory, performed laboratory testing of the rock samples collected.

Geophysical logging of the boreholes was performed by the U.S. Department of the Interior, Bureau of Reclamation, to aid the subsurface characterization including discontinuities and help define the stratigraphy of the project area. No independent report was produced. Refer to Appendix C for a summary of the laboratory test data, Appendix D for histograms of the rock engineering properties and Appendix E for the raw laboratory data. See report number 12 in Tables 4.1 and 5.1 for additional information.

4.3 Golder Associates (1992)

Golder Associates, Naperville, Illinois, was contracted by the Chicago District in September 1992 to perform an additional hydrogeologic investigation under the USACE/McCook-2 contract. This investigation included installation of piezometers, performing packer testing, slug and pressure testing, laboratory tests of rock permeability, measurement of static groundwater

4-8 levels, and conducting four groundwater pump tests. A summary of the results from the packer tests for this investigation are presented in Appendix C, histograms of the rock engineering properties in Appendix D, and the raw laboratory data in Appendix E. In addition, water quality samples were collected to provide baseline data on the groundwater chemistry. See report numbers 6 and 7 in Tables 4.1 and 5.1 for additional information.

4.4 STS Consultants (1996)

STS Consultants performed an investigation at the LASMA site under the MWRDGC at LASMA contract to the MWRDGC, following the change in the reservoir location. The investigation consisted of five borings to determine the quality of the rock for marketability and was performed in 1996. A summary of the results for the BTS and RQD tests performed are presented in Appendix C, histograms of the rock engineering properties in Appendix D, and the raw laboratory data in Appendix E. In conjunction with this investigation, Patrick Engineering tested select rock samples for engineering properties under contract to the Chicago District.

STS Consultants performed an evaluation of the Des Plaines River and Sanitary Ship Canal Waterways located adjacent to the LASMA reservoir site under the CUP McCook Reservoir and McCook Reservoir Drilling and Hydrogeologic Characterization contracts. The report from this investigation was submitted to the USACE in 2000. The information obtained from the borings was used to determine the depth of the water bodies and to evaluate the potential hydraulic connections between the surface water body and the bed rock aquifer. The investigation included RQD, BTS, unit weight (wet density), point load PLI, and UCS tests. Refer to Appendix C for a summary of the laboratory test data, Appendix D for histograms of the rock engineering properties and Appendix E for the raw laboratory data. See report numbers 11, 14, and 15 in

4.5 Patrick Engineering (1998)

Patrick Engineering also performed an investigation at the LASMA site. This investigation was performed in 1998 and consisted of 11 borings, 5 vertical and 6 angled. Conventional and hydrophysical borehole geophysics were performed as part of this program along with extensive laboratory rock testing. A summary of the results for the RQD, unit weight (wet density), and UCS tests conducted are presented in Appendix C, histograms of the rock engineering properties in Appendix D, and the raw laboratory data in Appendix E. The information was submitted to the Chicago district in a report entitled, “Report of Geologic Investigation for the CUP-McCook reservoir LASMA Site”.

4-9

A subsequent investigation was performed by Patrick engineering in 1998-1999 under the CUP McCook Reservoir - 5235.PO contract to further investigate the overburden soils at the LASMA site. This work included sampling and testing soil samples collected and the installation of 11 observation wells in the overburden. In addition, a total of four test pits were excavated in lagoons 3 and 10 of the LASMA facility to evaluate the ability to dig the overburden soils. The information was used to determine the stability of the excavated overburden slopes and recommend methods to control the flow of groundwater through the slopes. This was submitted to the Chicago District in a report entitled, “Report of Overburden Stability Investigation for the CUP-McCook Reservoir Site”. A summary of the results from the BTS, unit weight (wet density), and UCS tests conducted are presented in Appendix C, histograms of the rock engineering properties in Appendix D, and the raw laboratory data in Appendix E. See report numbers 9 and 10 in Tables 4.1 and 5.1 for additional information.

4.6 De Leuw, Cather & Company (1999)

The MWRDGC contracted with DeLeuw, Cather & Company for the design needed to relocate a 14 ft diameter tunnel that crosses the LASMA Site under the 73rd Street. TARP Tunnel Relocation contract. As part of this work, 3 borings were drilled by Everest Engineering Co.

along the alignment on the south bank of the Chicago Sanitary and Ship Canal. The information gathered from this investigation is documented in a report entitled, “Geotechnical Investigation – 73rd Street TARP Tunnel Relocation (Contract No. 97-156-2H)”. A summary of the results from the RQD and UCS tests conducted are presented in Appendix C, histograms of the rock engineering properties in Appendix D, and the raw laboratory data in Appendix E. See report number 13 in Tables 4.1 and 5.1 for additional information.

4.7 URS (2000)

The MWRDGC contracted with URS Corporation in 2000 for the design and construction of two tunnels and associated portals and shafts needed for facilitating open pit mining to develop a flood storage reservoir for LASMA. As part of this work, 2 borings were drilled to perform in-situ testing, laboratory testing, and geologic mapping. The information gathered from this investigation is documented in a report entitled, “McCook Haul Tunnels Design Project, McCook, Illinois”. A summary of the results from the BTS, unit weight (wet density), and PLI tests conducted are presented in Appendix C, histograms of the rock engineering properties in Appendix D, and the raw laboratory data in Appendix E. See report number 17 in Tables 4.1 and

5.1 for additional information.

4-10

4.8 Other Investigations – TSC, SCS (1980-1990)

Additional overburden investigations were performed at the LASMA site at various times by the MWRDGC. These included a series of investigations by TSC in 1980 and 1983 to analyze the stability of the berm along the Chicago Sanitary and Ship canal under the Proposed Railroad Spur to LASMA contract; an investigation by STS in 1990 to develop a design to control exfiltration from the lagoons under the LASMA-Water Infiltration Study contract; investigations by K&S Engineering in 2000 under the McCook Reservoir, Illinois, Deep Bedrock Boreholes contract and between 2006 and 2008 under the McCook CUP; LASMA, McCook, Illinois contract; and investigations performed by SEECO between 2000 and 2001 under the McCook Reservoir Overburden Investigation - Contract 73-161-CH contract. Refer to Appendix C for a summary of the laboratory test data, Appendix D for histograms of the rock engineering properties and Appendix E for the raw laboratory data. See report numbers 4, 16, 18, and 19 in

5-1

5.0 Project Ground Conditions

For purposes of defining stratigraphy at the reservoir excavation, shafts and along the tunnel alignment the Geotechnical/Geological Profile (Figure 3) was developed using maps from the reservoir quarry, previous tunnel construction and borings selected within close proximity of the shafts and tunnel with legible boring logs.

The subsurface conditions encountered during the investigation for this project were generally consistent with the data collected from previous investigations, and from published geological information. A statistical analysis of the entire geotechnical data set (1971 through 2008) yielded similar ranges and averages and the geotechnical and geological parameters, including in situ stresses, have been developed based upon the entire geological data set available in the project vicinity (Appendices A, C, and E). Refer to Table 5.1 for a listing of the boring logs considered for this report. Engineering properties from this data set were then assembled, grouped by rock formation, and presented in Table 5.3.

A description of the subsurface conditions is provided and should be read in conjunction with the exploratory borehole logs (refer to Appendices A and B), boring location plan (Figure 2), geological/geotechnical profile (Figure 3), and laboratory and in situ testing data (refer to Appendix E).

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5.1 Soil

Soils observed at the surface and recovered during drilling typically consisted of alluvium, glacial outwash deposits, and residual soils. Areas of fill inferred to be associated with dredging activities are present. In this report, soil descriptions are based on samples recovered during subsurface drilling and/or in-situ testing/sampling for the eight borings selected near the tunnel alignment. Table 5.2 presents the summary of the engineering properties of the onsite soils (USACE, 2009).

Standard Penetration Testing (SPT) was typically carried out until “SPT refusal” was recorded or rock encountered. SPT results are indicated on the exploratory borehole logs attached in Appendices A and B. Results of the onsite soils testing are attached in Appendix E.

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