A22 - ATTACHMENT H Redacted_Phase III Report.pdf

1.0 Executive Summary

2.0 Project Purpose

3.0 Project Description

Figure 3.1.1 - Shortened Engineered Channel (SEC) Figure 3.1.2 - Downstream Approach Channel Figure 3.1.3 - Engineered Channel -Width Transition Zone

4.0 Site History and Existing Data

Figure 4.1.1 - Brandon Road Lock Under Construction Figure 4.1.2 - Brandon Road Lock in the 1960s Figure 4.1.3 Brandon Road Canal

5.0 Scope of Work

6.0 Site Specific Geology

Figure 6.1.1 - Brandon Road Canal Table 6.1 – Slope Percentage and Erosion Potential Figure 6.1.2 - Columnar Section of the Silurian System in Northeastern Illinois Figure 6.1.3 - Brandon Road Lock and Dam Location near Sandwich Fault Table 6.2 - Summary of Seismic Parameters Figure 6.1.4 - 145-year Return Period – earthquake.usgs.gov/hazards/interactive Figure 6.1.5 - 950-year Return Period – earthquake.usgs.gov/hazards/interactive Figure 6.1.6 - 10,000-year Return Period earthquake.usgs.gov/hazards/interactive

7.0 Field and Laboratory Testing Results

7.1 Soil Sampling

Table 7.1 - Summary of Boring Information Table 7.2 - Summary of Boring Information Observation Wells

7.1.1 Hazardous Toxic and Radioactive Waste (HTRW) Sampling

Figure 7.1.1 - Example Boring Plan of Recommended HTRW Sampling Locations Table 7.3 - HTRW Sample Testing Summary

7.2 Rock Coring

Figure 7.2.1 - Marine Borings – RQD versus Elevation Figure 7.2.2 - Terrestrial Borings – RQD versus Elevation

8.0 Borehole Abandonment

9.0 Laboratory Soil Testing

Table 9.1 - Laboratory Test Results-Cohesive Soil Samples Table 9.2 - Laboratory Test Results-Non-Cohesive Soil Samples Table 9.3 – Standard Proctor Results Table 9.4 – Soil pH Table 9.5 – Soil Resistivity Table 9.6 – Corrosivity Analysis

10.0 Laboratory Rock Testing

Table 10.1 - Effective and Dry Unit Weight & Porosity of Rock Table 10.2 – Unit Weight of Rock Table 10.3 – Petrographic and X-Ray Diffraction Data (Weight Percent) Table 10.4 – Triaxial Compressive Strength – Method A Table 10.5 - Bulk Density and Compressive Strength Method C

Table 10.6 - Compressive Strength and Elastic Moduli of Rock Method D Table 10.7 - Rock Resistivity Per Two-Electrode Method Table 10.8 - Bulk Resistivity Per ASTM C1876 (Lock Wall Concrete) Table 10.9 – Rock Abrasiveness Table 10.10 - Splitting Tensile Strength of Rock Table 10.11 – Direct Tensile Strength of Rock Table 10.12 – Direct Shear Strength of Rock Table 10.13 – Sliding Friction of Rock Table 10.14 – Rock Specific Gravity and Absorption

11.0 Engineering Design Properties for Proposed Structures

11.1 Fill Estimates and Recommendations

Figure 11.1.1 – September 2022 Certified Total Project Plan Set Table 11.1 - Fill Areas and Volumes

11.2 Excavations

Table 11.2 - Cut Areas and Volumes

11.3 Preliminary Slope Stability Analysis and Assessment

Table 11.3.1 – Slope Stability Critical FOS Figure 11.3.2 - Rock Mass Stability (from NEH 2012) Figure 11.3.3 - Hardness and Unconfined Comp. Strength of Rock (from NEH 2012) Table 11.3.4 - Rock Mass Stability near Brandon Road Bridge Table 11.3.5 - Rock Mass Stability near RDB Guide Walls

11.4 Pile Supported Foundations

Table 11.4.1 - Storage Building Pile Length HP 14 x 102 Table 11.4.2 – Design Parameters for Piles Set in Rock

11.5 Preliminary Analyses of Impact on Existing Structures

11.6 De-Watering

11.7 Preliminary Seepage Analysis

Figure 11.7.1 - Temporary Cofferdam Profile Figure 11.7.2 - Temporary Cofferdam Plan View Figure 11.7.3 Seep/W Output for Brandon Road Cofferdam with Permeability 1 Figure 11.7.4 Seep/W Output for Brandon Road Cofferdam with Permeability 2 Figure 11.7.5 Seep/W Output for Brandon Road Cofferdam with Silty Clay Figure 11.7.6 Seep/W Output for Brandon Road Cofferdam with Silty Clay and Cutoff Wall

11.8 Preliminary Uplift Analysis

11.9 Preliminary Settlement Analysis

11.10 Electrical Conductivity Study

11.11 Construction Considerations

11.12 Tunneling and Directional Drilling

11.13 Boat Ramps

Figure 11.13.1- BR-2021-112 Sample

11.14 Proposed Sheet Pile Cells

11.15 Engineering Parameters Review and Discussion

Figure 11.15.1 - Table 2 from Preliminary Site Investigation Report

Figure 11.15.2 - Figure 19 from Preliminary Site Investigation Report Figure 11.15.3 - Backfill Soil Properties from Prelim. Site Investigation Report

11.16 Future Considerations

12.0 Surveying

13.0 Discussion

Figure 13.1.1 - Updated Boring Location Plan Segments Figure 13.1.2 - Updated Boring Location Plan Segments

Attachment A – Approved Work Plan Attachment B – Approved Site Preparation Report Attachment C – Approved Phase I Report Attachment D – Approved DPP Attachment E – Updated Phase II Report Attachment F – Boring Location Map – As-Drilled Attachment G – Boring Logs and Well Diagrams Attachment H – Subsurface Profiles Attachment I – Summary of Rock Drilling Data Attachment J – Rock Core Photographs Attachment K – Laboratory Soil Testing Data Attachment L – Laboratory Rock Testing Data Attachment M – September 2022 Certified Total Project Estimate Plan Set Attachment N - Rock Excavation Study Attachment O - SLOPE/W Slope Stability Analysis Attachment P – Pile Length/Pile Type Attachment Q – Preliminary Seep/W Seepage Analysis Attachment R – Electrical Conductivity Study Report

The drilling depth of terrestrial boring BR-2021-055 was split between that boring and an additional terrestrial boring, BR-2021-048A. Due to drill rig inaccessibility, two Terrestrial borings were converted to additional Marine borings. Boring BR-2021-056 became a Marine boring and remained as labeled and BR-2021-99 was changed to additional Marine boring BR-2021-063A. One (1) additional Marine boring (BR-2021-002) was added during the course of the field work due to on-going findings and coordination with the US Army Corps of Engineers (USACE), Rock Island District (MVR) personnel during execution of Phase II. Two (2) additional Marine borings (BR-2021-112 and -113) were also added to the contract through Contract Modification #2, dated August 05, 2022, for additional HTRW testing for a proposed boat ramp.

Depths of each boring and the Observation Wells were recommended by MVR in the Revised SOW. Bedrock was cored in 89 of the 94 borings to reach recommended depths.

Bedrock coring was performed in 28 of the 29 Marine borings and 61 of the 65 Terrestrial borings. Bedrock was also cored in each of the 9 Observation Wells. Drilling consisted of using 3 1/4-inch Hollow-Stem Augers (HSA) with 2-inch diameter rock cores, which was increased to 2.5-inch diameter cores for the Well installations. Four-inch casings were also used during drilling, as needed. Upon completion of the original SOW drilling and well installation for Phase II, KEG personnel mobilized back to the site for Site Clean-Up on July 22, 2022. Several borehole locations required some mild surface repairs and seeding, and the temporary fence staging area was removed, as directed by MVR personnel. Approval of Site clean-up was granted on July 22, 2022 after completion of activities. Photos of before and after site clean-up are included in Attachment B with the Approved Site Preparation Report.

Geotechnical laboratory testing of recovered soil and rock samples was implemented per the SOW and Revised SOW, as drilling progressed and after identifying samples suitable for testing and representative of the site conditions.

All tests performed to date are summarized in paragraphs and subparagraphs of this report and the Phase II Report, including Tables and Attachments, as noted. Actual laboratory results are also provided as Attachments in this report and the updated Phase II report. Portions of the laboratory testing were not completed at the time of submittal and approval of the Phase II report and have been added to the current version of the updated Phase II Report. See Attachment E – Phase II Report dated October 31, 2022 with updated field exploration and laboratory results and as summarized in the Phase III report, below.

Phase 3 – Contract Modification #2 SOW re-defined and clarified the overall design features of the project since the start of this Task Order, including revisions to the overall proposed site design completed by the District since development of the original contract SOW and Recommended Plan. The following report applies engineering analysis, judgment and discussion to the proposed project, based on the entire field exploration program and laboratory testing program, as summarized in the Phase I and Phase II reports.

2.0 Project Purpose

The U.S. Army Corps of Engineers - Rock Island District has contracted with Kaskaskia Engineering Group, LLC (KEG) under task order W912EK21F0068 in accordance with Indefinite Delivery Indefinite Quantity (IDIQ) contract W912EK20D0018. The primary objectives for the request of services were to define overall site geology and engineering properties of site soils and bedrock, and to perform engineering analyses related to bedrock excavation, electrical conductivity and grounding for the proposed electrical barrier feature, and design recommendations for future structural features for the Brandon Road Interbasin Project, located at Brandon Road Lock and Dam on the Des Plaines River in Joliet, Illinois.

3.0 Project Description

The Brandon Road Interbasin Project is located immediately downstream of the Brandon Road Lock and Dam. The navigation lock is located near Illinois Waterway River Mile No.

286 on the Des Plaines River in the City of Joliet, in Will County, Illinois.

A recommended conceptual plan was developed to control the upstream transfer of aquatic nuisance species (ANS) at the Brandon Road Lock and Dam on the Des Plaines River. This Tentatively Selected Plan (TSP), also identified as the Recommended Plan, has several components including an Engineered Channel (EC) in the area immediately downstream of the Brandon Road Lock and a flushing lock feature added to the lock itself.

Within the EC, several deterrents are proposed to be further modeled, developed, and designed and include: (1) electric barrier; (2) acoustic fish deterrents; and (3) air bubble curtain with additional EC area for future deterrent technologies. In addition to the deterrents, other features of the recommended plan include boat ramps upstream and downstream of Brandon Road Lock and Dam to provide needed access to the waterway for monitoring, utility installations to support the project, and buildings and other support facilities on either the right or left banks.

Since the submission of the Feasibility Report and the Recommended Plan, the Project Delivery Team (PDT) worked to optimize and define the geometric layout of the EC.

Building upon the Feasibility Report as well as multiple Value Based Design Charrettes (VBDC), an Engineering Evaluation Report (EER) was prepared dated March 2022 that recommends pursuing a Short Engineered Channel (SEC) option as depicted in Figure 3.1.1, below.

4.0 Site History and Existing Data

The Brandon Road Lock and Dam was initially constructed from 1927 to 1933. There has been additional construction done to the site in 1935, 1967, 1980, 1984, 1986, and 1995.

It was added to the National Register of Historic Places on March 10th, 2004. It is a significant component of the Illinois Waterway and connects Lake Michigan to the Mississippi River and beyond. The Brandon Road Lock and Dam was originally going to include a power plant, but lack of sufficient funding prevented this addition. Existing data was extremely limited due to record keeping changes/losses over time. See the Approved Phase I Report in Attachment C, for limited historical data previously provided by MVR. The picture in Figure 4.1.1 below is of the interior of the lock during initial construction.

Figure 4.1.1 - Brandon Road Lock Under Construction

Brandon Road Lock and Dam connects commercial barges and recreational vessels through the Illinois Waterway. The picture Figure 4.1.2 below is facing the upstream lock walls in the 1960’s and illustrates the amount of water that the lock walls must retain to allow for vessels to pass through safely.

Figure 4.1.2 - Brandon Road Lock in the 1960s

The Brandon Road Lock and Dam is near Illinois Michigan (I&M) Canal Lock Number 5 that was constructed in 1848. This canal was effective at navigating the inland waters but was too small for commercial shipping. Chicago uses the I&M to transport sewage out of the city since it is parallel to the Illinois Waterway. The construction of The Brandon Road Lock and Dam led to the flooding of Lock Number 5 and allowed traffic to pass from the canal to the Des Plaines River. The junction lock kept the waterway’s boat traffic from straying into the I&M Canal. This canal is pictured in Figure 4.1.3, below.

Figure 4.1.3 Brandon Road Canal

The US Army Corps of Engineers installed an electric barrier in 2002 on the Romeoville Lock and Dam north of Brandon Road Lock and Dam to prevent aquatic nuisance species from entering Lake Michigan. The US Congress identified Brandon Road Lock and Dam as an additional site for enhanced efforts to prevent the spread of invasive species in 2015. The US Geological Survey tested the feasibility of an acoustic deterrent system with multiple sounds in 2017 to develop sound maps and determine if ambient sounds interfere with sound projections. This study aided in the development of the plan for the Brandon Road Interbasin Project.

5.0 Scope of Work

The scope of work was developed by the Corps of Engineers - Rock Island District. To support this project, KEG has prepared this comprehensive Phase III report to summarize the tasks as set forth in the project Scope of Work (SOW), and Modifications to the SOW, as summarized above in Section 1 - Executive Summary.

In general, the SOW consisted of three (3) phases, as follows:

1. Site preparation, marine and terrestrial geophysical testing, test pits, and engineering services.

2. Marine and terrestrial drilling and rock coring, installation of observation wells, field and lab testing, and engineering services.

3. Development of a comprehensive report containing the boring logs, testing results, plots, engineering conditions, and recommendations. Includes feasibility study related to rock excavation in the channel, evaluation of site electrical conductivity concerns, and recommendations for engineering design properties for proposed structures.

The phases of work completed, followed the Work Plan (WP), dated Revised November 22, 2021 and the Drilling Program Plan (DPP) signed January 26, 2022 and approved by USACE, except for where described in this report.

The geotechnical exploration and laboratory testing programs were developed by the Corps of Engineers and discussed with KEG and KEG’s subcontractors.

Specific elements of the geotechnical exploration and laboratory testing program are described in greater detail below in Section 7. – Field and Laboratory Testing Results.

6.0 Site Specific Geology

The area is near the junction of the Wheaton Morainal Country of the Great Lake Section and the Kankakee Plain of the Till Plains Section.

Review of the Will County soil survey obtained from http://websoilsurvey.nrcs.usda.gov indicates that the soil within the project limits is composed of several different soil types.

A Map showing the types and coverage areas is shown in Figure 6.1.1. The overall summary is as follows:

Figure 6.1.1 - Brandon Road Canal mottled with red and green. The Markgraf Member is 12 to 22 feet thick, and is light gray, medium bedded dolomite. Three different units of the Markgraf Member are noted along the Des Plaines River, and include a silty dolomite, a slightly silty and argillaceous dolomite with bands of chert nodules, and a slightly argillaceous dolomite that also has bands of chert nodules. The Romeo Member is 18 to 34 feet thick and consists of light gray to white dolomite with pink mottling. It often contains silicified fossils and bands of chert nodules.

Figure 6.1.2 - Columnar Section of the Silurian System in Northeastern Illinois

A discussion of the seismic information for the project site is included below. The site is located about 5 miles northeast of the Sandwich Fault Zone, which has been historically inactive. Regionally, the New Madrid Seismic Zone, located about 350 miles south of the site, is an active zone with the capability of producing large earthquakes.

Image From Beck Jr., M.E., "Aeromagnetic Map of Northeastern Illinois and Its Geologic Interpretation", 1965

Figure 6.1.3 - Brandon Road Lock and Dam Location near Sandwich Fault

A determination of Seismic Site Class was based on the method described by the Illinois Department of Transportation (IDOT) AGMU Memo 09.1 - Seismic Site Class Definition and the IDOT provided spreadsheet titled: ‘Seismic Site Class Determination.’ Using these resources, the controlling global site class for this project is Soil Site Class C.

Additional seismic parameters were calculated for use in design of any structures and evaluation of liquefaction potential. Published information and mapping from the USGS, including software directly applicable to the AASHTO Guide Specifications for LRFD Seismic Bridge Design, were used to develop the parameters for the site location. The values, based on Soil Site Class C, are summarized below in Table 6.2.

Figure 6.1.4 - 145-year Return Period – earthquake.usgs.gov/hazards/interactive

Figure 6.1.5 - 950-year Return Period – earthquake.usgs.gov/hazards/interactive

Figure 6.1.6 - 10,000-year Return Period earthquake.usgs.gov/hazards/interactive

7.0 Field and Laboratory Testing Results

7.1 Soil Sampling

Ninety-Four (94) borings and Nine (9) Observation Wells were completed beginning on February 07, 2022, through June 01, 2022. Sixty-four (64) of the borings were Terrestrial-based and Thirty (30) were Marine-based borings drilled from a barge. The Observation Wells were Terrestrial-based.

The original Revised SOW boring total provided by MVR was Ninety-three (93) borings, with Twenty-seven (27) of those borings being Marine-based and Sixty-six (66) of those being Terrestrial-based; with Twelve (12) of the 66 Terrestrial borings listed as Optional.

The SOW Modification 1, dated February 07, 2022, relocated some of the previous boring locations due to modifications and additions to the Recommended Plan layout of the project. The SOW Modification 2, dated August 05, 2022, called for two (2) additional HTRW borings BR-2021-112 and BR-2021-113 to be completed in the upper pool/mooring area. These additional HTRW borings were completed on October 03, 2022

During the course of the Phase II drilling operations, the drilling depth of terrestrial boring BR-2021-055 was split between that boring and an additional terrestrial boring, BR-2021- 048A. Another Terrestrial boring (BR-2021-99) was changed to a Marine boring (BR- 2021-063A) and One (1) additional Marine boring (BR-2021-002) was added and completed as part of the overall program. See Tables 7.1 and 7.2 - Summary of Boring Information below, for details of the completed borings and wells. Elevations in Tables

7.1 and 7.2 were compiled from surveying done after the borings were completed to confirm final boring locations and surface elevations for accuracy due to potential offsets or other impacts to the staked locations during field exploration. The accompanying field

Borings were completed using three drill rigs consisting of a Diedrich Model D-120 All- Terrain rig and a Geoprobe 7822DT All-Terrain rig for the Terrestrial borings and Observation Wells and a truck-mounted Mobile B57 rig on a spud barge for the Marine borings. Hollow stem augers were used to drill through soil and/or top of weathered bedrock to permit sampling of these materials. The hollow stem augers were advanced until refusal was encountered. Samples of the unconsolidated materials were obtained using a 2-inch outside diameter (OD) split-spoon sampler. The number of blows needed to drive the split-spoon into the soil was recorded on the field logs along with a description of the recovered soil. Split-spoon sampling was conducted in accordance with ASTM D 1586-84 and Engineering Manual EM 1110-2-1907. Samples were placed in standard geotechnical sample jars and labeled as specified by KEG’s Field Engineers.

7.1.1 Hazardous Toxic and Radioactive Waste (HTRW) Sampling

General areas for recommended HTRW soil sampling were also provided by MVR during the course of the Phase II drilling program. See below Figure 7.1.1 - Example Boring Plan of Recommended HTRW Sampling Locations.

Figure 7.1.1 - Example Boring Plan of Recommended HTRW Sampling Locations

A range of both Terrestrial and Marine borings were flagged for collection of soil samples for HTRW sampling and testing. Poor sample recovery hindered the initial attempts at collecting sufficient soil samples of the recommended Marine borings at the time of completion of the entire borehole, resulting in a return to each of the respective Marine boring locations for additional attempts of soil sample collection using different sampler were completed adjacent to the lock, such as for installation of the Observation Wells through the lock walls.

7.2 Rock Coring

Bedrock coring was performed in 29 of the 32 Marine borings and 61 of the 64 Terrestrial borings. Bedrock was cored using a 2-inch inside diameter (NQ) core barrel and attempted in most cases with 10-foot runs. Rock coring was conducted according to ASTM D 2113-83 and Engineer Manual (EM) 1110-1- 1804. Rock core was logged and placed in standard waxed boxes. Total Recovery and Rock Quality Designation (RQD) for each core run were recorded and rock core photographs were taken during field exploration. Figure 7.2.1 and 7.2.2 below show plots of the RQD versus Elevation for the Marine and Terrestrial borings, respectively.

Figure 7.2.1 - Marine Borings – RQD versus Elevation

Figure 7.2.2 - Terrestrial Borings – RQD versus Elevation

Rock core information from this exploration is summarized in Attachment I, with rock core photographs summarized in Attachment J.

8.0 Borehole Abandonment

Upon completion, each boring was backfilled using bentonite chips and cuttings for the Terrestrial borings and a cement-bentonite grout for the Marine borings. Grout was placed from the bottom up using a 1-inch diameter PVC grout pipe. Boreholes BR-2021-001 and BR-2021-009, the two borings through the body of the dam, were backfilled using bentonite chips and cuttings, and a cement-bentonite grout was used to backfill the upper portion of the holes.

Because of the cohesionless soils encountered during many of the borings along the peninsula, some boreholes collapsed after removal of the hollow-stem augers before the backfilling process was started. In these instances, only the upper part of the borehole was backfilled.

9.0 Laboratory Soil Testing

Cohesive samples were tested for natural moisture content (ASTM D2216) and Atterberg Limits (ASTM D4318). The results of Atterberg limits tests performed on cohesive samples are shown in Table 9.1. Moisture contents of all the soils are shown on the boring logs. See Attachment K – Laboratory Soil Testing Data for specific laboratory test result sheets and plots of Atterberg results.

Figure 11.1.1 – September 2022 Certified Total Project Plan Set

The current plan set is included as Attachment M - September 2022 Certified Total Project Estimate Plan Set. This does not include the amount of fill required for the boat ramps since they are still being designed. Cohesive structural fill should be placed and compacted to at least 95 percent of its maximum dry density as determined by the Standard Proctor Compaction test (ASTM D 698). KEG recommends any structural fill have a liquid limit less than 45 and a plasticity index of 0 to 25. Acceptable non-organic fill soils include materials designated by USCS as CL, ML, CL-ML, SP, SW, GP, and GW by ASTM D 2487. The rock excavated from the engineered channel would be acceptable if it is crushed to be used as an aggregate.

11.3 Preliminary Slope Stability Analysis and Assessment

Limit equilibrium pseudo-static stability analysis using SLOPE/W was performed using several of the proposed sections provided along the channel. For each section, the Left Descending Bank (LDB) and the Right Descending Bank (RDB) was analyzed. The slopes were analyzed for the conditions of the existing slope and the proposed construction with the proposed structural additions to the channel, including retaining walls across both banks, and the concrete slab at the bottom of the channel. Table 11.3 shows the stations analyzed and the borings used for the soil and bedrock parameters.

Two conditions were modeled for each scenario: end-of-construction (short-term) and long-term stability. A critical factor of safety (FOS) was calculated for each condition.

According to the current standard of practice, the target FOS is 1.5 for end-of-construction and long-term slope stability analysis.

To model the end-of-construction (short-term) conditions, full cohesion, and a friction angle of 0 degrees were assumed for cohesive soils. Nominal values for cohesion were used with full friction angle to model the long-term conditions to analyze the theoretical condition where pore water pressure has dissipated. Nominal values were between 50 and 1,500 psf for the cohesive soils, with friction angles between 26 and 38 degrees.

Because mostly river borings were performed on the LDB beyond a certain point on the west end of the project, no pertinent information about the soils on that side was recovered. Based on this, a silty clay was estimated based on empirical methods and modeled to account for the soil overburden on the LDB. The values assumed for this soil are a unit weight of 120 pcf, with a cohesion of 1,000 psf for the short-term condition and a cohesion of 100 psf and 26 degrees friction angle for the long-term condition. The concrete was modeled as a high-strength material, considering that it is very stable and has infinite strength; similarly, the bedrock was modeled as an impenetrable material.

Additionally, distributed loads of 150 psf were included for the roads and 350 psf for the proposed utility building.

The Spencer Method was used to calculate the critical failure surfaces and FOS for the proposed conditions. The FOS obtained in the analysis are shown in Table 11.3.1, below. SLOPE/W program output from this analysis can be found in SLOPE/W Slope Stability Analysis, Attachment O.

Figure 11.3.2 - Rock Mass Stability (from NEH 2012)

Figure 11.3.3 - Hardness and Unconfined Comp. Strength of Rock (from

NEH 2012)

Tables 11.3.4 and 11.3.5 above show the rock quality at Brandon Road Bridge and RDB Guide Walls. There is a mixture of ratings from Stable to Unstable. The Unstable ratings were given based off poor RQD and appear in the top twenty or so feet near Borings BR- 2021-091, -092, and –096. Particular care and monitoring should be taken near these locations during any excavation activities.

Using instrumentation like establishing fixed monitoring points that are surveyed and monitored on a fixed schedule, and accelerometers to measure and record both vibrations and overpressures during blasting operations, if used for excavation, will be important to monitor the short-term stability of the existing structures. Permanent instrumentation to monitor potential stability or erosion concerns near the foundations of these existing structures should also be considered.

As outlined in the accompanying Brandon Road Rock Excavation Study, there are several excavation methods that have minimal impact on nearby surrounding rock and existing structures that can be used when excavating near the existing guide walls, the Brandon Road Bridge foundations, and in and around the lock. Trenching or using hydraulic excavators with a hammer attachment could get to the required depths of excavation without much disturbance. Other methods include wire line sawing or using chemical pre-splitting near the edges of the area to be excavated to protect surrounding rock while blasting. Vibrations caused by blasting should be limited based on the structure type and importance. See Attachment N – Rock Excavation Study for additional information.

11.6 De-Watering

Locks along the Illinois Waterway used to be de-watered using a poiree dam system, but that was condemned in the 1990’s. Construction and installation of new bulkhead slots, planned for 2023 at Brandon Road, will utilize steel stoplogs with seals between them which will allow for de-watering of the Brandon Road Lock.

Dewatering of the EC for future maintenance activities could be done with the use of temporary cofferdams, like the one proposed for the construction of this project as discussed below. A permanent pumping station could also be considered.

11.7 Preliminary Seepage Analysis

A de-watering cofferdam may be used for excavation of the river channel floor. Figures

11.7.1 and 11.7.2 below show the section and plan view of the proposed cofferdam from the Brandon Road Interbasin Project - September 2022 Certified Project Estimate plan set.

The expected material that will be used to construct the cofferdam is well-graded shot rock with 400 lb. top size borrowed from the site. Riprap gradation curves were made as part of the Phase I Report investigation at the Test Pits along the presumed borrow area peninsula. The curves showed a range of “Percent Finer by Weight for 3-lb Rocks” which were the smallest rocks weighed. The results ranged from around 84% finer by weight for the 3-lb rocks at Test Pit BR-2021-001P, to 57% finer by weight at Test Pit BR-2021- 005P. See Attachment C – Approved Phase I Report for more information. There are concerns of potential voids existing when this material is used for the cofferdam due to the low fine content, especially from material pulled from the southwest end of the peninsula near Test Pit BR-2021-005P. Further investigation and planning are needed to ensure the material used to create the cofferdam is graded well enough to avoid sloughing or washing out of finer materials.

The temporary cofferdam will be built to an elevation of El. 509.3 to account for the 10-year flood event, so this analysis assumes the work will cease once that water elevation is reached. A preliminary steady-state seepage analysis was performed to roughly predict flow totals through the body of the cofferdam for future design and construction considerations. Seepage considerations may require an upstream impervious blanket that should be removed later if it restricts drainage during drawdown.

Figure 11.7.1 - Temporary Cofferdam Profile

Figure 11.7.2 - Temporary Cofferdam Plan View

Exact permeability values are unknown for the proposed cofferdam well-graded shot rock material, so several different analyses were run in Seep/W to give a range of outputs.

Analysis was done with a typical permeability value for well-graded gravel/sandy gravel using Ky/Kx values of 1, 0.5, and 0.1 to account for the material being compacted to varying degrees. Analysis was also done with a smaller permeability value that is typical for silty gravels/silty sandy gravels with the same Ky/Kx values. The full results are shown in Attachment Q – Preliminary Seep/W Seepage Analysis. Figures 11.7.3 and 11.7.4 below show the outputs for the two materials at a Ky/Kx ratio of 0.1.

The seepage quantities calculated varied greatly between the six models, giving total seepage values between about 22 and 2154 gallons per hour per square foot, which reflects the uncertainty in the calculations. Seepage quantities will vary greatly based on any joints or fractures in the rock mass, and the exact specifications of the cofferdam construction material. Using the preliminary seepage quantities from these models give an estimate inflow of between 5,700 gallons and 560,000 gallons of water per hour.

Further study is recommended in order to evaluate a good estimate for the hydraulic conductivity for the dam in order to determine pumping needs.

Figure 11.7.3 Seep/W Output for Brandon Road Cofferdam with Permeability 1

Figure 11.7.4 Seep/W Output for Brandon Road Cofferdam with Permeability 2

If plans call for a more permanent cofferdam in the future, using a silty clay fill material will greatly decrease the amount of seepage through the body of the dam. This was also modeled with the same geometry, and the results are shown in Figure 11.7.5 below. A case where a bentonite-grout mix was used for a cutoff wall was modeled as shown in Figure 11.7.6 below. The estimated seepage through these structures come out to approximately 0.004 and 0.0005 gallons per hour per square ft. Similar to the planned temporary cofferdam, further study would be needed to obtain better estimates for the hydraulic conductivity of any material used in a permanent structure for more accurate pumping predictions.

Figure 11.7.5 Seep/W Output for Brandon Road Cofferdam with Silty Clay

Figure 11.7.6 Seep/W Output for Brandon Road Cofferdam with Silty Clay and Cutoff Wall

11.8 Preliminary Uplift Analysis

De-watering cofferdams were checked against hydrostatic uplift, using the structure's weight versus the hydrostatic buoyancy force. No check at the toe of the cofferdams was considered because it is unlikely for an uplift failure to be produced when bearing on/in bedrock.

As specified in the preliminary plans, the embankment (Hg) height is 19.3 ft, and the normal tailwater height (Hw) is 15 ft. For the temporary cofferdam, the unit weight of the well-graded gravel/sandy gravel (γg) was assumed to be 135 pcf. For a more permanent cofferdam, the unit weight of the silty clay (γg) was assumed to be 125 pcf. According to these assumptions, the estimated FOS are shown below.

De-watering Cofferdam (Well-Graded Gravel/ Sandy Gravel Embankment)

𝐹𝐹𝐹𝐹 =

𝛾𝛾𝑔𝑔 × 𝐻𝐻𝑔𝑔

𝛾𝛾𝑤𝑤 × 𝐻𝐻𝑤𝑤

(135 𝑝𝑝𝑝𝑝𝑝𝑝 − 62.4 𝑝𝑝𝑝𝑝𝑝𝑝) × 15 𝑝𝑝𝑓𝑓 + 135 𝑝𝑝𝑝𝑝𝑝𝑝 𝑥𝑥 4.3

62.4 𝑝𝑝𝑝𝑝𝑝𝑝 × 15

𝐹𝐹𝐹𝐹 = 1.78

De-watering Cofferdam (Silty Clay Embankment) 𝛾𝛾𝑔𝑔 × 𝐻𝐻𝑔𝑔 𝛾𝛾𝑤𝑤 × 𝐻𝐻𝑤𝑤

(125 𝑝𝑝𝑝𝑝𝑝𝑝 − 62.4 𝑝𝑝𝑝𝑝𝑝𝑝) × 15 𝑝𝑝𝑓𝑓 + 125 𝑝𝑝𝑝𝑝𝑝𝑝 𝑥𝑥 4.3

62.4 𝑝𝑝𝑝𝑝𝑝𝑝 × 15

𝐹𝐹𝐹𝐹 = 1.58

11.9 Preliminary Settlement Analysis

The proposed structures in the recommended plan will be constructed on structural fill that will be compacted to at least 95% or imbedded directly into the bedrock. This indicates that the magnitude of the settlement will be minimal in the construction process.

It is not anticipated to cause down drag on the piles. Therefore, no settlement calculations have been performed for the proposed structures.

11.10 Electrical Conductivity Study

The results of subsurface exploration and testing with respect to the resistivity, conductivity and corrosion properties of the site soils and bedrock as listed above and preliminary recommendations for addressing these material properties for use in design and construction of the interbasin improvements are summarized in an Electrical Conductivity Study summarized under separate cover in Attachment R– Electrical Conductivity Study Report.

11.11 Construction Considerations

Construction of the EC, the accompanying structures and guide walls, and the concrete floor of the lock will require extensive rock and soil excavation. An accompanying report, the Brandon Road Rock Excavation Study, gives recommendations on different methods and considerations for this excavation process, based on the findings of this geotechnical investigation. Some general construction considerations for both in-the-wet and in-the-dry include:

Protection of the existing structures, including the lock and dam, Brandon Road

Bridge, the guide walls, and the rock formations along the left and right descending banks, is a critical factor when considering which methods of excavation to choose.

Guarding the remaining bedrock will also be crucial for long term stability. Some examples of ways to protect the adjoining structures include limiting blasting vibrations, using chemical or mechanical pre-splitting techniques around the edges of excavation, or using percussion drilling near the structures.

Blasting could be a cost-effective option to excavate in areas further away from the delicate existing structures. If blasting is used on this project, a blasting program developed by a qualified person must be followed, and include guidelines on allowable Peak Particle Velocity, plans to minimize or prevent production of flyrock and air blast hazards, and plans to minimize overblasting. Generally, all applicable federal, state, and local laws and regulations regarding handling, storing, and transporting explosives should be followed.

If rock excavation is done in-the-wet, minimizing impacts to waterway traffic, when possible, should be considered. A maximum navigation channel width of 75 ft is generally allowed for adjacent work in the navigation channel at this site for any work occurring with active navigation in the channel.

Using instrumentation like establishing fixed monitoring points that are surveyed and monitored on a fixed schedule, and accelerometers to measure and record both vibrations and overpressures during blasting operations, if used for excavation, will be important to monitor the short-term stability of the existing structures.

Any bedrock exposed during construction and excavation should be inspected to determine if any detrimental features are encountered. If any unexpected detrimental features are found, more excavation or foundation treatment may be required.

Construction of the EC and accompanying buildings will produce a lot of overburden and rock spoil. The material can be stockpiled and reused for various purposes of this project, including but not limited to mass grading, structural backfill, erosion protection, and pavement base.

11.12 Tunneling and Directional Drilling

Horizontal Directional Drilling (HDD) may be used on this project for the construction of utilities crossing beneath the EC. HDD is a construction technique where a borehole is drilled in a horizontal manor under a waterway or ground surface, followed by installation of a pipe by pulling the pipeline through the excavated borehole. The hole is drilled at an arc line from an entry point, below the river, and back up to resurface at an exit point on the opposite side. Potential entry and exit points for this project are over 250 feet apart on opposite sides of the EC.

Soft to very stiff sandy clays and silty clays, as well as medium-dense to dense sands and gravels were observed in the borings along either side of the river channel, which would be the presumed entry and exit locations of any proposed HDD installation. See Subsurface Profiles, Exhibit H. For the anticipated geology that may be encountered by the HDD methods, there is a possibility of inadvertent return and fluid migration through the variable overburden sands, gravels and clays as the holes advance through those stratigraphic layers to the dolomite bedrock. Detailed monitoring of fluid pressures and visual inspection of the installation as the holes are advanced, should be performed during construction, to monitor for any irregularities that could potentially indicate that an inadvertent return is developing.

Any open entry and exit access pit excavations, if required, performed adjacent to existing structures or roads should maintain a minimum horizontal distance of one horizontal to one vertical (1H:1V) from the road and/or bottom of any existing structure foundations to the bottom of the open excavation. Any excavation encroaching within this 1H:1V may require underpinning of the existing structures depending upon their use and/or shoring.

11.13 Boat Ramps

The recommended plan includes the construction of a boat ramp upstream of the Brandon Road Lock and Dam and an additional one downstream near the peninsula. The design and construction should adhere to EM-1110-2-410 Design of Recreation Areas and Facilities.

The boat ramp surfacing must be designed to withstand the weight of the boat, trailer, vehicle, and heavy wave action. The surface must also be rough to provide traction to the vehicles since mud and slime tend to accumulate on the surfaces. This is achieved with a grooved herringbone pattern down sloped from the center of the ramp to the outside edge. The surface should be constructed with reinforced concrete or prestressed concrete with a minimum thickness of 6 inches with a 6-inch bedding course compacted to 100% density, and a subgrade compacted to 95% density. Alternative surface materials include asphaltic concrete; however, algae can form just above and below the surface and sediments can be deposited that cause the ramp to become slick and hazardous to use. Precast reinforced or prestressed concrete plank ramps may be used if the area is sheltered from waves or currents and can extend existing ramps during periods of extreme drawdown.

The fluctuation of the water level must also be considered. The slope of the ramp should be steep enough to permit the vehicle to launch the boat without submerging exhaust pipes or wheel bearings. The grade must be a minimum of 12 percent and a maximum of 16 percent (it is preferred to have a grade of 14 percent). The excavation of the ramp should also slope toward the water at a grade that avoids excessive cuts to fit in smoothly with the surroundings. The break over angle at the point of the beginning of the ramp or at any other change in the ramp grade should not exceed 7 degrees. If the conditions prevent this, a vertical curve should be used to prevent dragging of the surface. The ramp should have a minimum of one 75-foot diameter area for vehicles to turn around and a 150-foot interval on a continuously sloping ramp.

The shoulder of the boat ramp should be stabilized with rock to prevent erosion and provide support to prevent vehicles from going off the pavement. The rock should be riprap or quarry run and should be sized for the anticipated wave action or current. The rock should then be chocked and grouted to prevent trailer wheels or individuals from falling into the holes. This will prevent injuries and the theft of the rock; however, it reduces the effectiveness by interfering with the dissipation of wave energy. Since the effectiveness is reduced, it is recommended that an increase in the size of the rock used otherwise be chosen.

Cohesive structural fill should be placed and compacted to at least 95 percent of its maximum dry density as determined by the standard Proctor compaction test (ASTM D 698). KEG recommends any structural fill have a liquid limit less than 45 and a plasticity index less than 25. Acceptable non-organic fill soils include materials designated by USCS as CL, ML, CL-ML, SP, SW, GP, and GW by ASTM D 2487. This indicates that the crushed rock from the excavated channel would be acceptable.

The subsurface exploration in the proposed upstream construction area indicated very soft silty sand to a termination depth of 20 feet in BR-2021-002. Similar material was encountered in BR-2021-112 and 113 to a termination depth of 8.5 feet. Environmental testing was conducted on the samples and indicated high levels of heavy metals (including iron, lead, and arsenic) and semi-volatile organic compounds (such as benzo(a)pyrene, pyrene, etc.). The material should be excavated during construction and disposed of according to EPA regulations. A sample from boring BR-2021-112 is pictured in Figure 11.13.1 below.

Figure 11.13.1- BR-2021-112 Sample

The subsurface exploration in the proposed downstream construction area indicated silty clay and gravel fill with bedrock at an elevation of approximately 500.7 feet.

Environmental testing was not conducted in the proposed area. The grade and surface of the boat ramp should follow the guidelines above. In order to achieve the ideal grade of 14 percent, additional rock may need to be excavated. This is not included in the rock excavation estimate for the overall project and design plans for the ramps are required to provide any additional construction recommendations.

If construction is performed during the winter season, fill materials should be carefully observed to see that no frozen soil is placed as fill or remains in the base materials upon which fill is placed.

In addition to the minimum density requirements listed above, the soil must be stable, i.e., not “pumping” or rutting excessively under construction traffic, prior to placing additional fill. Field density tests should be performed on each lift of fill to document that proper compaction is achieved.

11.14 Proposed Sheet Pile Cells

Proposed sheet pile cells are planned at the downstream ends of the Engineered Channel. Soil stratigraphy information downstream is limited to borings conducted in the river along the center of the channel and the right descending bank, which had little to no soil before transitioning to bedrock, and borings along the left descending bank peninsula, which had a mix of cohesive and non-cohesive soils to depths of about 20 ft before transitioning to bedrock.

The overburden soils and shallow competent bedrock encountered across the site are not conducive to driven applications of cell installation. Any cell construction will have to be considered using templates and excavating and seating the cells into the underlying bedrock using rock excavation methods as recommended in this report. Uplift of the cells can be accomplished with increased embedment into competent bedrock, use of rock anchors seated into deeper more competent bedrock or creating flared or toed bases backfilled over with concrete to seat and bond them in the underlying bedrock. Seal coats or working platforms will be required in the floor of the cells over the underlying bedrock, to reduce potential of any water migration through existing fractures in the bedrock surface. Another option would be to consider a bedrock grout curtain program across the footprints of any cells, prior to excavating and setting the cells into the bedrock.

11.15 Engineering Parameters Review and Discussion

Based on a recommendation in the SOW, available historic engineering properties and information, provided by MVR and summarized in the Preliminary Site Investigation Report, dated June 2021; was reviewed with respect to properties developed during the course of this geotechnical exploration and laboratory testing task order. Little historical information specific to the design and construction of Brandon Road Lock and Dam was still available according to USACE due to the changing of various headquarters and storage of materials over the years. What information that was available, was provided in the Preliminary Site Investigation report and also consisted of some plan segments and historical photographs of the Lock and Dam during construction. Some existing boring log data was provided, including some borings from the 1930’s and 1970’s.

Of particular interest are tables and figures provided in the Preliminary Site Investigation report, labeled “Table 2. Brandon Road Engineering Properties (1973)” and another table referenced as “Figure 19. Brandon Road Engineering Properties (1982).” Both tables are shown below as Figure 11.15.1 and 11.15.2, respectively.

Figure 11.15.1 - Table 2 from Preliminary Site Investigation Report

Figure 11.15.2 - Figure 19 from Preliminary Site Investigation Report

Based on the available data referenced above and review of the historic boring logs and test information provided; the data obtained in the current task order correlates well with the historical data. However, the newer rock and soil data indicates properties more accurately and generally less conservative than used in the previous design work for the site. The specific test results completed for this task order are all summarized in tables above in Section 9.0 and 10.0, respectively. Based on those results, a summary of engineering properties of the rock and soils encountered at the site are as follows.

Table 2 above had a recommended saturated unit weight and dry unit weight for bedrock encountered at the site, of 166 pcf and 162 pcf, respectively. Based on the multitude of rock unit weights obtained at various depths throughout the dolomite bedrock, new results had a range of saturated unit weights of 162.3 pcf to 171.6 pcf, with an average saturated unit weight of 166.5 pcf. Just a half a cubic foot shy of the recommended historical value.

Likewise, the bedrock dry unit weight range was 159.8 pcf to 166.6 pcf with an average of 163.1 pcf. Just 1.1 pcf greater than the historical value. This was deemed a very good correlation, based on the number of new tests performed and at various depths within the bedrock mass, not just at shallow bedrock depths.

Compressive strength of the rock also correlated well with the historical values. New compressive strength values of the rock ranged from 5,992 psi to 27,079 psi, with an average of 13,907 psi. The compressive value of 10,000 psi in Table 2, was in the range of new data, however, the newer data results in more values greater than 10,000 psi to consider, particularly for bedrock that appears to get more competent with depth across the site. Thus, based on the historical value of 100 tsf for a recommended bearing capacity, values of up to 3 times greater are possible for bearing capacity of the the site bedrock based on the new test data.

Sheer strength of the bedrock also correlated well with respect to the historical peak strength, with the new data ranging from 10 to 24 psi, versus the historical recommended value of 16.3 psi. Ultimate shear was exceedingly better than the previous 0 psi, with a much larger range of 150 psi to 300 psi. Like the new compressive strength results, these results indicate the rock could be considered more competent than previously estimated.

Friction angle values of the bedrock ranged from 36.6 to 71.3 degrees with new test results, with an average value of 60.7 degrees. This was a bit higher on average than the previous 52 degrees.