Soils and Foundation Report.pdf

SOILS AND FOUNDATIONS REPORT

NO. 09-08

PROJECT OH PRA-CUVA 18(1),164(1)

FITZWATER AND WASTE WEIR BRIDGES

FITZWATER ROAD

CUYAHOGA VALLEY NATIONAL PARK

CUYAHOGA COUNTY, OHIO

U.S. Department of Transportation Federal Highway Administration

Eastern Federal Lands Highway Division 21400 Ridgetop Circle

Sterling, VA 20166

November 2008

TABLE OF CONTENTS

PAGE

INTRODUCTION

GENERAL

PROJECT DESCRIPTION

GEOLOGIC SETTING

REGIONAL GEOLOGY

SOIL SURVEY

PROCEDURES AND RESULTS

GENERAL

SAMPLING

FIELD TESTS AND MEASUREMENTS

DATA SUMMARY

LABORATORY TESTING

FINDINGS

DESIGN ANALYSIS AND CONCLUSIONS

BRIDGE FOUNDATIONS

EMBANKMENTS/FILL SLOPES

RETAINING WALLS

PAVEMENT

RECOMMENDATIONS

BRIDGE FOUNDATIONS

ABUTMENT WALLS

RETAINING WALL – GEOCELL WALL

PAVEMENT

CONSTRUCTION CONSIDERATIONS

SPECIAL CONTRACT REQUIREMENTS (SCR’S)

DISCLAIMER/LIMITATIONS CLAUSE

REFERENCES

APPENDICES

APPENDIX A..……………………………………....................…………………………...Figures

APPENDIX B..……………………………...............Boring Location Plan and Subsurface Profile

APPENDIX C..…………………………………………....…………………………...Boring Logs

APPENDIX D.……………………………………………...........………...Laboratory Test Results

APPENDIX E.……………………………………….……………..Design Analysis Computations

APPENDIX F.……………………………………………..............Special Contract Requirements

APPENDIX G.………………………………………………...........…Representative Photographs

Note: Design changes made subsequent to distribution of this report and prior to project advertisement will be documented in a memo inserted after the title page.

U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

SOILS AND FOUNDATIONS REPORT

NO. 09-08

PROJECT OH PRA-CUVA 18(1),164(1)

FITZWATER AND WASTE WEIR BRIDGES

FITZWATER ROAD

INTRODUCTION

GENERAL

This report summarizes the results of our subsurface explorations, laboratory testing, and design analyses and presents recommendations for replacement of two (2) bridges and new pavements for Project OH PRA-CUVA 18(1),164(1). The project is located on Fitzwater Road, over the Cuyahoga River, in Cuyahoga Valley National Park in Cuyahoga County, Ohio. The general site location is shown on Figure 1 in Appendix A.

PROJECT DESCRIPTION

Cuyahoga Valley National Park is located in northern Ohio, between Cleveland and Akron. The project involves replacement of two bridges along Fitzwater Road in Cuyahoga County, east of the Town of Independence. The project was identified in Eastern Federal Lands Highway Division’s (EFLHD’s) Engineering Study, dated March 2002, to include Structure No. 6160 018P, Truss Bridge over Cuyahoga River and Structure No. 6160 019P, Waste Weir Bridge over the Ohio Canal. The Truss Bridge (also referred to as the Fitzwater Bridge in this report) was constructed over the Cuyahoga River in 1922 and subsequently rehabilitated in 1995. The bridge consists of a single span truss, 200 feet long, supported by concrete abutments. The bridge structure and abutments are in poor condition, and were noted in recent inspections to be critically deficient and functionally obsolete. In addition, a significant amount of scour is evident at both abutments, and the west abutment appears to be severely undermined. The Fitzwater Bridge was closed to the public in November, 2007.

East of the Fitzwater Bridge is the Ohio and Eerie Canal, which once connected Lake Eerie with the Ohio River and runs parallel to the Cuyahoga River. The canal is spanned with a 20-ft. by 20-ft. box culvert. Upstream of Fitzwater Road, flow is diverted from the canal over a waste weir to form an auxiliary channel adjacent to the canal, which rejoins the canal a short distance downstream. The waste weir channel is spanned by a 76-ft. long bridge, which was constructed concurrently with the Fitzwater Bridge. The FLH Bridge Inspection Program also inspected the Waste Weir bridge in conjunction with the Fitzwater Bridge and found it to be functionally obsolete.

The closing of the Fitzwater Bridge has restricted access to the Maintenance Yard. Four alternatives were considered to restore access to the Maintenance Yard.

SOILS AND FOUNDATION REPORT NO. 09-08

PROJECT OH PRA-CUVA 18(1), 164(1)

FITZWATER AND WASTE WEIR BRIDGES

Alternative 1A/1B – Extend the abandoned portion of Fitzwater Road on a new switchback alignment. This alternative was not selected primarily because of concerns about the stability of a past landslide in the vicinity of the project.

Alternative 2 – Create an access road from Pleasant Valley Road that begins at Fitzwater

Road, parallels the railroad alignment, then turns to follow the alignment of the North East Ohio Regional Sewer District access road until it reaches Pleasant Valley Road. The alignment is controlled by the presence of wetlands, utilities and the existing railroad.

Although Alternative 2 was not selected for a permanent solution, the option is being constructed for temporary access to the Maintenance Yard during construction of the new bridges.

Alternative 3 - Construct a temporary bridge across the existing bridge or on a new alignment. This alternative was not selected.

Alternative 4 - Construct a permanent bridge on a new alignment north of the existing bridge, tying into the existing roadway alignment on the west side of the Cuyahoga River. This alternative was selected for this project.

GEOLOGIC SETTING

REGIONAL GEOLOGY

According to the Ohio Department of Natural Resources (1987), “Glacial and Surficial Geology of Cuyahoga County, Ohio,” the geology in the vicinity of the proposed project consists of recent alluvium overlying older lacustrine deposits. The alluvium deposits consist of clastic deposits and associated organic debris, notably on floodplains of the Cuyahoga, Chagrin and East Branch Rocky Rivers. The Lacustrine Deposits are described as undifferentiated silt and clay, thin on the Lake Plain and Escarpment, thick and interbedded with sand and gravel in terraces along the Cuyahoga and Chagrin River valleys. It includes thick outwash deposits with interbedded sand and gravel on the Plateau south of Solon. Contours on this publication show approximate depth to the bedrock surface. At the project site, this depth is estimated at El. 150 – 200. With the ground surface at approximately El. 600, this means that bedrock could be up to 400 feet or more below ground surface at the site.

SOIL SURVEY

According to the United States Department of Agriculture Web Soil Survey, the project site is underlain predominantly Chagrin Silt Loam to the west of the Ohio Canal and Geeburg-Mentor Silt Loams to the east of the Ohio Canal. The Chagrin Silt Loam consists of occasionally flooded, very deep, well-drained soil. The surface layer has a moderate content of organic matter, and the slowest permeability is moderate. The Geeburg-Mentor Silt Loams consist of steep to very steep, very deep, moderately well-drained to well-drained soils. The surface layer has a moderate content of organic matter. The slowest permeability is very slow to moderate. An area to the southeast of Fitzwater Road is classified as “Dump”, with no further explanation. Refer to Figure 3 of Appendix A, for a Soil Survey Map of the project area.

FITZWATER AND WASTE WEIR BRIDGES

PROCEDURES AND RESULTS

GENERAL

The Eastern Federal Lands Highway Division’s (EFLHD) Subsurface Exploration Team conducted a subsurface investigation program at the project site between April 8 and 10, 2008, and again between April 28 and 29, 2008. The subsurface investigation program consisted of drilling a total of 9 borings along the proposed alignment. The borings were generally classified into two groups, pavement borings and bridge borings. The pavement borings, designated RB-1 through RB-3, were drilled to depths varying between 3.7 and 10.0 ft. The bridge borings, designated FB-1 through FB-3 (Fitzwater Bridge), and WB-1 through WB-2 (Waste Weir Bridge) were drilled to depths of up to 97.0 ft. Boring HB-1, a hand auger boring, was drilled to a depth of 6.5 feet to ascertain the depth of alluvial silt and sand at the proposed Fitzwater Bridge Pier 1. All borings were advanced to termination depths using a CME 750, rotary, track-mounted drill rig. Boring Location Plans and generalized Subsurface Profiles are provided in Appendix B.

SAMPLING

Borings were drilled to depths ranging from 3.7 to 97.0 ft below the existing ground surface. Borings were advanced using 3¾ -in. (inside diameter) hollow stem augers. Standard Penetration Tests (SPT) were performed using a 2¼ -in. (outside diameter) split-spoon sampler in accordance with AASHTO 7200-87 and AASHTO T206-87.

Representative portions of split-spoon samples were preserved in glass jars. Five (5) undisturbed/thin-walled Shelby tube samples of soil were collected at the site in accordance with AASHTO T207. The undisturbed/thin-walled samples were preserved within their respective sample tubes. All samples were later transported to EFLHD’s Materials Testing Laboratory in Sevierville, Tennessee. Samples selected for Laboratory Testing were shipped to Froehling and Robertson, Inc. (F&R) of Richmond, Virginia.

The sampling sequence and associated jar samples for each boring are presented on its appropriate Boring Log in Appendix C.

FIELD TESTS AND MEASUREMENTS

Boring locations were determined from features present on-site and by referencing the existing roadway.

Boring elevations were determined by extrapolation of topographic lines from site maps provided by EFLHD’s Survey Section. SPT soil samples were recovered by driving the split-spoon sampler a distance of 24-in., or until refusal, into the undisturbed soil under the action of a 140-pound automatic hammer free-falling 30 inches. Samples were typically recovered at 5-ft intervals up to 50 ft deep.

Samples were typically taken at 10.0- or 15.0-ft intervals below 60 ft. Samples in the shallow pavement borings were typically continuously recovered. The number of hammer blows required to advance the split-spoon sampler the middle 1.0 ft of the 24-in. sample interval is designated as the “Standard Penetration Resistance” or N-Value. Split-spoon refusal is defined by 50 blows per 1-in. of penetration of the split-spoon sampler. The number of blows required to advance the sampler through each 6-in.

interval was recorded on field boring logs. The relative consistency of each cohesive sample was estimated using a calibrated pocket penetrometer. A field description by color and texture was made for each recovered soil sample. The depth to groundwater, if present, was measured at the time of completion of each boring.

FITZWATER AND WASTE WEIR BRIDGES

DATA SUMMARY

The EFLHD Subsurface Investigation Team performed the following field tests and measurements during the course of the subsurface exploration. The results of field tests and measurements were recorded on the driller’s logs and appropriate data sheets in the field. These data sheets and logs contain information concerning the boring methods, samples attempted and recovered, indications of the presence of various material such as gravel, pebbles, organic matter, etc., and observations of groundwater. They also contain interpretations by the exploration team leader of the subsurface conditions based on the performance of the equipment and cuttings brought to the surface by the drilling tools. Therefore, the field data represents both factual and interpretative information.

The boring logs in Appendix C represent a compilation of field laboratory data and description of the soil samples by a geotechnical engineer. These records occasionally do not include all data recorded on driller’s logs and field data sheets, but do include all information considered relevant to the design and preparation of this report.

Groundwater level readings were made at the times and under the conditions stated on the boring logs. Fluctuations in groundwater level due to seasonal variations, rainfall, temperature, and other factors not evident at the time measurements were made should be expected.

LABORATORY TESTING

The laboratory testing program for this project was conducted as described below. Laboratory testing was performed by Froehling & Robertson, Inc. (F&R) of Richmond, Virginia. All tests were conducted in accordance with applicable AASHTO/ASTM standard test methods.

The primary purpose of laboratory testing was to aid in the classification and evaluation of the engineering properties of soils present at the site. Additionally, tests were performed to provide an understanding of strength and compressibility of the lacustrine silt and clay soils. Laboratory tests were performed on 8 jar samples and 3 undisturbed Shelby tube samples and included natural moisture content (AASHTO T-265), Atterberg limits (AASHTO T-89 & T-90), particle size analysis (AASHTO T-88), classification (AASHTO M-145), pH (AASHTO T-289), UU triaxial strength (AASHTO T-296) and consolidation (AASHTO T-216). Laboratory test results are summarized in Tables 1 and 2. Laboratory test result sheets are provided in Appendix D.

FITZWATER AND WASTE WEIR BRIDGES

Table 1 – Index Properties of Soils

Soil Classification Boring No.

Sample No.

Sample Depth

(ft)

Water Content

LL PI Fines

AASHTO Description

FB-1 J-2 5 – 7 28.3 - - 62.0 A-4 Brown silt, some sand

FB-1 J-4 13 – 15 25.1 - - 4.0 A-3 Gray sand, trace silt

FB-1 J-8 27 – 29 22.7 33 15 99.4 A-6 Gray clayey silt

FB-1 J-12 45 – 47 25.2 37 17 99.7 A-6 Gray silty clay

FB-2 J-2 5 – 7 20.8 - - 62.4 A-4

Brown Silt, some sand, trace gravel

FB-2 J-4 15 – 17 15.4 14 NP 10.2 A-1-b Gray-brown sand, little gravel, little silt

FB-2 J-10 45 - 47 33.4 42 21 99.6 A-7-6 Gray silty clay

FB-3 J-9 42 – 44 27.3 38 17 99.8 A-6 Gray silty clay

Table 2 – Consolidation and Strength Properties of Soils

Boring No.

Sample No.

Sample Depth

(ft)

Dry Density, γd

(pcf) P'c

(psf) Cc Cr eo

UU

Triaxial Strength

(psf)

FB-1 ST-1 26.5 108.5 - - - 0.53 1,670

FB-1 ST-1 26 100.7 8,500 0.145 0.028 0.65 -

FB-2 ST-1 51.5 100.9 - - - 0.64 778

FB-2 ST-1 51 93.8 5,300 0.210 0.065 0.76 -

FB-3 ST-2 41.4 99.8 - - - 0.66 1,238

FB-3 ST-2 41 92.9 9,500 0.242 0.035 0.76 -

P'c = Preconsolidation Pressure; Cc = Compression Index; Cr = Recompression Index, eo = Initial Void Ratio

FITZWATER AND WASTE WEIR BRIDGES

FINDINGS

Boring logs describing the subsurface conditions encountered in each boring may be referenced in Appendix C of this report. Profile sheets in Appendix B present generalized subsurface profiles illustrating the general geologic conditions that may be anticipated at the bridge abutments and piers.

Descriptions of the soil conditions encountered during the subsurface explorations conducted at the site are presented below. The categories and descriptions below are indicative of the various types of subsurface soils encountered and does not suggest stratification.

Pavement Borings

A total of 3 pavement borings, designated RB-1 through RB-3, were drilled along the proposed alignment west of the Cuyahoga River. As indicated on the boring logs, the soil profile typically consists of fill over Lacustrine silt and clay. Pavement borings were nearly continuously sampled from 1 foot below ground surface to a maximum depth of 10 ft.

Fill – Fill associated with the existing roadway along Fitzwater Road was encountered in Boring RB- 1 through RB-3. The fill material is characterized as gray, gravelly sand to black silty sand (coal slag). SPT N-values recorded within this stratum ranged between 18 blows per foot (bpf) and 50 blows for 0.3 ft, indicating medium dense to very dense soil. The soils in this stratum were typically dry to moist. Fill was encountered below pavement to depths of 0.4 to 0.5 ft.

Lacustrine Silty Clay – This stratum consists of brownish-gray to black silty clay. SPT N-values recorded within this stratum ranged from 1 to 3 bpf, indicating very soft to soft soil consistency.

This stratum was encountered below the fill in borings RB-1 and RB-3 to depths of 2.6 to 5 ft. The full depth of this deposit was not penetrated.

The groundwater table was not encountered in Borings RB-1 through RB-3, however, soil samples were visually described as wet at approximately 5 ft.

Bridge Borings

A total of six bridge borings, designated FB-1 through FB-3, WB-1 through WB-2, and HB-1, were drilled along the alignment of the proposed bridges. The subsurface conditions at both bridge sites will be discussed together since they are in close proximity to each other and subsurface conditions are similar.

Fitzwater and Waste Weir Bridges

Due to difficult site access, borings for Fitzwater Bridge piers were drilled at an offset distance of 17 ft (FB-1) and 61 ft (FB-2) from the proposed pier locations. Boring FB-3 was drilled in the vicinity of the approach embankment for the west pier of the Fitzwater Bridge. Boring HB-1 was hand-drilled in an attempt to ascertain the depth of alluvium at Pier 1. For the Waste Weir Bridge, boring WB-1 was drilled at the location of the center pier, and boring WB-2 was drilled on the Towpath Trail, which is the location of Waste Weir Bridge West Abutment and Fitzwater Bridge East

FITZWATER AND WASTE WEIR BRIDGES

Abutment. These borings generally encountered Alluvium overlying Lacustrine Deposits of silt and clay. Embankment fill placed for the Towpath Trail was encountered over the alluvium in boring

WB-2.

Fill – Fill associated with embankment construction for the Towpath Trail was encountered at the ground surface. The fill stratum is described as brown silty clay. One SPT sample was taken within the embankment fill, and the N-value recorded for that sample was 5 bpf, indicating medium stiff clay consistency. Although the contact between fill and alluvium was not encountered in the samples, we estimate the bottom of this stratum at Elevation 609.5 ft.

Alluvium – Alluvium consisting of brown to gray silty fine to medium sand, trace organics (peat and wood pieces) was encountered in borings FB-1, FB-2, FB-3 and HB-1. SPT N-values recorded within this stratum ranged from weight of hammer (WOH) to 8 bpf, indicating very soft to medium stiff soil consistency. This stratum was encountered from the ground surface to Elevations ranging from 599 to 605 ft.

Lacustrine Sand and Gravel – This stratum was encountered underlying the alluvium in Borings FB-1, FB-2, FB-3 and WB-2. The lacustrine sand and gravel is described as grayish brown to brown, medium to coarse sand, trace to little silt, to brown sand and gravel. SPT N-values recorded within this stratum ranged from 2 to 13, indicating very loose to medium dense soil.

This stratum was encountered to Elevations ranging from 593 to 595.5 ft.

Lacustrine Silt and Clay – The lacustrine silt and clay was usually encountered below the lacustrine sand and gravel, except in FB-3, where 1.2 ft. of silty clay was encountered above the lacustrine sand and gravel. The lacustrine silt and clay is characterized by gray to brownish-gray, silty clay, with occasional pockets of sandy clay. SPT N-values recorded within this stratum ranged between WOH and 25 bpf, indicating very soft to very stiff soil consistency. The full depth of the lacustrine silt and clay deposit was not penetrated. Borings in this stratum were terminated at Elevations ranging from 514.0 to 558.5 ft. The geologic map indicates that the depth to bedrock in the Cuyahoga River Valley may be as much as 300 to 400 feet below ground surface.

The groundwater table in the bridge borings was encountered between Elevation 603.1 and 610.5 ft.

DESIGN ANALYSIS AND CONCLUSIONS

Design analyses for construction of bridge abutments and piers, bridge approaches, retaining walls, and pavement sections were performed based on the strength parameters of onsite soils encountered within the depth of our explorations, design loading information provided by Bridge, laboratory testing results and project information available from Highway Design.

BRIDGE FOUNDATIONS

Based on available information, the existing bridge over the Cuyahoga River is supported on a deep open box structure supported on a footing that may be as much as 40 feet below the ground surface. During the design process a similar type of deep footing foundation, along with driven piles and drilled shafts, FITZWATER AND WASTE WEIR BRIDGES were considered. The deep footing foundation would require a very deep excavation. In addition, the proposed Fitzwater Bridge includes two piers, where a deep footing foundation would not be feasible within the river. Drilled shafts would have a high capacity, but the overall pile cap would not be substantially different size than for driven piles. Also, drilled shafts would require drilling within the Cuyahoga River. According to Ohio Department of Transportation (ODOT), driven pipe piles are the most commonly used friction pile in the area. In addition, driven piles have the advantage of being installed without the need for drilling. Several diameters of pipe pile were considered (16-inch, 18-inch, 24-inch and 30-inch). The 24-inch diameter was chosen to maximize pile capacity while keeping the size close to what is typically used by ODOT. Therefore, 24-inch, closed-ended driven pipe piles are considered the most feasible and economical deep foundation system for the subsurface conditions at this project.

Design analyses were performed based on data obtained from our subsurface investigation program and laboratory test results, where available. The soil properties presented in Table 3 below were developed based on empirical correlations between available laboratory test results and SPT N-values. Design analyses were performed using a generalized subsurface profile at each structure location and using the material properties presented in Table 3.

Table 3 – Soil Parameters for Analysis

Material Type Unit Weight, γ

(pcf)

Friction Angle, φ

(deg.)

Cohesion, c (psf)

Fill 125 ≤ 32 -

Alluvium 115 29 -

Lacustrine Sand and Gravel 120 32 -

Lacustrine Silt and Clay 115-120 - 750 – 2,000

Scour

Scour elevations were established based on the Hydraulics Report of July 2008. Axial capacities were reduced based on calculated scour. Scour elevations are shown in Table 4.

FITZWATER AND WASTE WEIR BRIDGES

Table 4 – Scour Elevations

Structure Location Scour

Elevation (ft)

East 582.4 Abutments

West 579.7

Pier 1 574.7 Fitzwater Road Bridge

Pier 2 576.2

Waste Weir Bridge Pier and Abutments N/A

Axial Capacity

The nominal (ultimate) resistance of individual piles was evaluated in accordance with FHWA (2006), Design of Driven Pile Foundations, and Section 10 of AASHTO (2007), LRFD Bridge Design Specifications. The FHWA computer program DRIVEN (v1.2) was used to calculate axial capacities for driven piles at each of the two bridge sites.

Design analyses suggest that 16-in. and 24-in. pipe piles, driven closed-ended, will be adequate for providing support of structure loads. The analyses indicate that axial pile capacity will be developed by a primarily by side resistance in the Lacustrine Silt and Clay. Pile capacities were reduced by scour or downdrag conditions where applicable.

Design bearing graphs which summarize nominal pile resistance versus depth and factored pile resistance versus depth are presented in Appendix E. Computer program DRIVEN (v1.2) computation output files may also be referenced in Appendix E.

Uplift

Uplift resistance is typically taken as the side resistance calculated for downward axial side resistance minus 20 percent. Uplift for individual piles were calculated in this way and are included on the resistance plots in Appendix E.

Settlement

Settlement of pile groups was evaluated in accordance with Subsection 10.7.2.3.1 of AASHTO (2007).

The piles for the bridge substructures are founded in the Lacustrine silt and clay. The group settlement was calculated using the equivalent footing method shown in AASHTO 10.7.2.3.1. Based on laboratory tests on the silt and clay soils, the tested soils have maximum preconsolidation pressures ranging from 5,300 psf (depth = 51 ft bgs) to 9,500 psf (depth = 41 ft bgs). When the stresses from the added bridge loads are imposed on the foundation soils, the resulting final stresses are still below the maximum preconsolidation pressure. Therefore, settlement will occur in the recompression range of the soil.

Based on laboratory testing, a recompression ratio (RR) of 0.03 was used for settlement analyses.

FITZWATER AND WASTE WEIR BRIDGES

The west abutment of the Fitzwater Bridge includes embankment fills with a maximum height of 13 feet.

This embankment fill loading will cause additional settlement of up to 1.1 inches at the west abutment substructure. To reduce this settlement, the embankment fill, with an additional 4 feet of surcharge, should be placed a minimum of 2 months prior to driving piles at the west abutment. There should be adequate time programmed in the project schedule to allow for 2 months of embankment surcharge. The Acccess Road will be available for hauling fill for the approach embankment. Based on our calculations, this preload and surcharge should cause 0.5 inches of settlement, resulting in a post-construction embankment settlement of 0.6 inches. The differential settlements between substructures on the Fitzwater Bridge will therefore be limited to approximately 0.3 inches. A summary of consolidation settlements at each substructure is shown in Table 5

Lateral Capacity

Lateral capacity of the drilled shafts was analyzed using the computer program AllPile (v 7.8). Soil parameters used for lateral capacity analysis are shown in Table 6. Lateral capacity was analyzed assuming scour at the Fitzwater Bridge and no scour at the Waste Weir Bridge in accordance with recommendations in the Hydraulics Report.

Table 5 – Foundation Settlements

Structure Substructure Pile Group

Settlement (in) Differential Sett.

Between Substructures (in)

Embankment Settlement (in)

0.0 East Abutment 0.1

0.3

Pier 1 0.4

Pier 2 0.4

0.3

1.11

Fitzwater Road Bridge

West Abutment 0.1

East Abutment 0.2

Pier 0.2

0.1

Waste Weir Bridge

West Abutment 0.1

1 Total consolidation settlement at location of substructure due to loading from embankment.

FITZWATER AND WASTE WEIR BRIDGES

Table 6 – LPILE Lateral Soil Parameters

Soil Type γb pcf φ deg c ksf k pci e50/Dr

Sand/Gravel 53 33 0 33 35

Soft Clay 56 - 65 0 0.50 – 1.0 85 - 300 0.9 – 1.35

Stiff Clay 65 - 70 0 1.0 – 1.8 300 - 500 0.7 – 0.9

Temporary Access Bridge

After completion of the subsurface exploration program, it was determined that a temporary bridge should be constructed over the culvert on Fitzwater Road to support equipment for bridge construction.

No explorations were conducted at the location of the temporary bridge. The nearest borings to this site are WB-1, located on natural ground below the proposed temporary bridge, and WB-2, located on the Towpath Trail. For analysis, properties of the embankment were assumed based on boring WB-2, and soil properties below the embankment level were assumed based on soil properties in WB-1. A shear strength of 800 psf was assumed for embankment fill material. The bearing resistance was calculated using a bearing capacity based on two layers of soil: the assumed granular base/subbase below the existing AC pavement, and the assumed cohesive fill for the remainder of the embankment.

EMBANKMENTS/FILL SLOPES

The largest embankment fills along the alignment are at bridge approaches. Approach fill at the West Abutment of the Fitzwater Bridge reaches a maximum height of approximately 13 ft. Fill heights at the zone between Fitzwater Bridge East Abutment and Waste Weir Bridge West Abutment reach approximately 5 to 7 ft.

Stability

Slope stability analysis was performed for the highest embankment fill slope on the project, which is located at the West Abutment of Fitzwater Bridge. Borings FB-2 and FB-3 indicate that the proposed embankment will be constructed over approximately 10 ft of silty sand, overlying 10 ft of medium to coarse sand, overlying silty clay varying in undrained strength from 750 to 1,500 psf.

For foundations soils, soil strength parameters were selected based on SPT N-values and the results of field and laboratory testing and are generally in accordance with the strength parameters presented in Table 3. The computer program SLOPE/W was utilized for the stability analyses. Design analyses indicate that the resulting short-term (no strength gain, high water table) safety factor was 1.7.

Embankment Settlement

Settlement is expected to be greatest at the approach embankments to the west abutment of the Fitzwater Bridge, due to the height of the embankment and presence of the Lacustrine silt and clay stratum at this location. Settlement analyses were performed using the soil parameters in Table 2 and using correlations to the soil properties presented in Tables 1.

FITZWATER AND WASTE WEIR BRIDGES

Settlement calculations indicate that a maximum total consolidation settlement of 1.1 inches will occur within the silt and clay soils. Post-construction settlement will be reduced by the preload and surcharge described previously.

Approach Embankment Settlement and Downdrag

Settlement at the approach embankment will impose downdrag forces on the piles at the Fitzwater Bridge West Abutment. Post-construction settlement of 0.6 inches is expected at the West Abutment.

Therefore, piles at the West Abutment should be designed for an additional downdrag load. To compensate for the additional loading, piles could be driven deeper to increase capacity, or alternatives should be considered to reduce or eliminate downdrag loads, such as lightweight fill or friction reducers.

The calculated additional loading due to downdrag was calculated to be 30 kips per pile, for 16-inch diameter piles or 45 kips per pile, for 24-inch diameter piles. If piles are designed for downdrag loading, a load factor of γp = 1.0 should be used for downdrag loading in accordance with AASHTO (2007), since dynamic monitoring will be performed. Design analysis computations are presented in Appendix E.

RETAINING WALLS

In order to prevent placing embankment fill material within the floodplain south of the Cuyahoga River, an earth retaining structure will be constructed along the Towpath Trail. The proposed grades at this location suggest that the retaining wall will have exposed heights of up to 7 feet. Boring WB-2, drilled on the Towpath Trail, and boring FB-1, drilled near the Fitzwater Bridge East Abutment, indicate that the proposed walls on the north side of the new bridge abutment will likely bear within fill soils at approximate Elevations 615 to 617 ft. On the south side of the bridge abutment, the proposed walls will likely bear at approximate Elevations 618 to 620 ft. The highest wall to be constructed on the Towpath Trail was evaluated for stability due to the nature and consistency of foundation soils at that location.

The following retaining wall alternatives were evaluated for support of the proposed embankment. The wall alternatives were evaluated on the basis of cost, stability, constructability, and aesthetics.

1. Geocell Wall with a vegetated face – This alternative consists of a geosynthetic-reinforced soil (GRS) with geocells to provide confinement and surficial stability, with the ability to grow vegetation on the face. Additionally, the geocells are capable of providing erosion resistance during high water events.

2. Modular Block Wall with vegetated face – This alternative consists a geosynthetically-reinforced, modular block facing with vegetation. However, the face angles recommended by manufacturers of this system are typically flatter than for the geocell wall and would require a larger footprint for the embankment.

3. Rockery Wall –This alternative consists of dry-stacking large rocks that would give an aesthetically-pleasing stone wall appearance. This alternative would require construction of a GRS and possibly a reinforced concrete footing for stability.

The geocell wall was determined to be the most suitable wall alternative for this application. The geocell wall does not require any specialized equipment for construction. Vegetation can be planted in the front face of the wall to improve its aesthetics.

FITZWATER AND WASTE WEIR BRIDGES

The geocell wall was designed at an angle of 80 degrees in order to limit the quantities of construction materials and the area of disturbance. In addition, the wall face angle will more closely match the bridge abutment wingwall with a steeper face batter.

Geogrids were chosen for the geosynthetic reinforcement. Geocell facing units were specified for constructing the geocell wall in order to promote vegetation growth at the slope face and to eliminate slope face sloughing and erosion. Geocell units are available in 8-in vertical heights for use in this project. Vertical geogrid spacings were held at 16-in in order to assist in the constructability of the geocell wall.

The geocell walls are designed to bear on the existing silty clay embankment fill of the Towpath Trail.

Geocell walls were designed to provide a minimum embedment of 2-ft from the slope toe to the slope face.

Drainage measures with sufficient redundancy are incorporated into the geocell wall. Select granular fill behind the face will drain water to weep holes at the wall face. No hydrostatic pressures are anticipated to develop behind the geocell wall, therefore no hydrostatic pressures were considered in design.

The existing soils within the Towpath Trail embankment have abundant quantities of silt and clay. These soils are known to present construction challenges in compaction and quality control when used within embankment applications. Further, these soil materials are known to display poor performance as a fill in both unreinforced soil embankments and in reinforced structures. Based on the listed poor soil properties, the majority of on-site soils are not suitable for embankment construction. Stability analyses have been completed assuming that imported fill competent will meet the unclassified borrow material and placement specifications in accordance with the FP-03 Standard Specifications and with the recommendations contained within this report.

Soil properties chosen for analyses and design were based upon the results of the boring logs, the SPT field blow counts, and the results of laboratory testing. Soil properties used for analyses and design are presented below in Table 7.

Geogrid embedment lengths were designed based on the analysis results that met the safety factor requirements. The geogrid reinforcement strength required to achieve the minimum factor of safeties was then calculated using the computer program ReSSA. Since the embankment has a geocell wall on both sides, and the design geogrid lengths overlap, geogrid should extend in continuous sheets from one geocell wall to the opposing geocell wall. Each geogrid layer will tie into the geocell on either side of the embankment.

The geocell wall was analyzed for external, internal, and compound stability. External stability evaluations completed were for global stability and translational stability only. The existing fill subgrade should be proofrolled prior to placement of geogrids and foundation geocells. The foundation geocells should cover the entire width of the embankment.

Global stability, also referred to as deep-seated rotational stability, was completed employing the AASHTO/FHWA-Bishop method of analysis. Translational stability, also referred to as horizontal sliding resistance, was completed using the Spencer method of analysis for a 2-Part Wedge. Internal and compound stability were completed using the AASHTO-Bishop method of analysis.

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Table 7 - Summary of Material Properties Used in RSS Stability Analysis

Material Cohesion (psf) Friction Angle (degree)

Moist Unit Weight (psf)

Reinforced Fill 0 34 125 Existing Fill 400 0 120

Loose Silty Sand 0 28 120 Silty Sand w/Gravel 0 31 120

Silty Clay 600 - 1,000 0 118 - 120

The critical cross-section chosen for analysis was determined based on the site conditions, design plans and profiles, encountered subsurface conditions, laboratory test results, and on the design requirements for slope angle and embedment from the slope face discussed above.

The minimum factor of safety required for each failure mode evaluated is summarized below in Table 8.

Geogrid reduction factors and geogrid-soil interaction parameters applied to the geogrid reinforcement are included in the ReSSA analyses results provided in Appendix E.

Table 8 - Minimum Factor of Safety Required for Each Failure Mode

Results

The results of the design analyses are tabulated below in Table 9. The computer generated output is provided in Appendix E. These outputs provide the soil properties, the section geometry analyzed, reinforcement spacing, type, strength and interaction parameters, the calculated factor of safeties for global and horizontal stability, and plots of the calculated critical failure plane.

Failure Mode Minimum Factor of Safety Reinforcement Pullout 1.50

Global Stability 1.30 Horizontal Sliding Stability 1.30

Local Bearing Failure γH ≤ 3c Compound Stability 1.30

Internal Stability 1.30

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Table 9 - Summary of RSS Analyses Results

Global Stability Factor of Safety1

Horizontal Sliding

Stability Factor of

Safety

3-Part Wedge

Analysis Factor of

Safety

Maximum

RSS

Height2 (ft)

Minimum Geogrid

Embedment Length (ft)

Ultimate Required

(lb/ft)3

Long-Term Allowable Required

(lb/ft)3

1.88 2.99 2.21 7.0 15.0 1000.0 454.0

1The Global Stability analyses considered the internal, compound, and deep-seated failure cases. The minimum factor of safety considering these three cases is presented here.

2The maximum heights shown here correspond to the 70% plans. The heights are measured from the wall toe and the top of the edge of shoulder at the slope face.

3The long-term geogrid reinforcement strengths presented here represents the minimum primary reinforcement strength required.

PAVEMENT

Flexible pavement design analyses were conducted for new construction areas using the 1997 AASHTO Pavement Design, DARWin(tm) Pavement Design program (version 3.01). DARWin was used to determine the future structural number (SN) for each pavement section based on several traffic and soil parameters.

Flexible pavement design analyses were conducted for a 20-year design period. The design analyses to determine the 18-kips equivalent single axle loads (ESALs) were performed using the Rigorous ESAL Calculation in DARWin and were based upon traffic count and vehicle classification data estimated based on information obtained from the scoping report. Initial Average Daily Traffic (ADT) value of 200 was used for the pavement design.

The effective roadbed soil resilient Moduli (MR) were correlated from the CBR values. Resilient Modulus used for the analysis was 7,500 psi, which correspond to a CBR value of 5. Other parameters specified in the analyses include a reliability of 80 percent, and overall standard deviation of 0.49, an initial serviceability index of 4.2, and a terminal serviceability index of 2.5.

The results of the pavement design analysis are presented in Appendix E.

For constructibility reasons, analyses of new pavement sections considered a minimum section consisting of 1.5 inches of Superpave asphalt concrete pavement (SACP) surface course (1/2 inch nominal maximum size aggregate (NMSA), < 3.0x106 ESALs, Type IV pavement smoothness); 2.5 inches of SACP base course (3/4 inch NMSA, < 3.0x106 ESALs) and 8.0 inches of aggregate base (grading C or D).

RECOMMENDATIONS

BRIDGE FOUNDATIONS

Based on the scour depth, subsurface soil strength and compressibility, a deep foundation system comprised of steel pipe piles is the recommended foundation system for both bridges. Two pile sizes

FITZWATER AND WASTE WEIR BRIDGES

were evaluated for support of the proposed bridges. Depending on the loading conditions we recommend supporting the bridges on 16-in. or 24-in. diameter steel pipe piles designed as friction piles bearing primarily in the Lacustrine silt and clay deposits.

Pile lengths should be determined using the Nominal Bearing Resistance graphs presented in Appendix E. A resistance factor of 0.65 should be used for strength limit states, and a resistance factor of 1.0 should be used for service limit states. Uplift loading resistance factor of 0.8*0.65 was applied to the side resistance only. The strength limit state resistance factor was selected according to Subsection 10.5.5.2.3 of AASHTO (2007) for piles with driving criteria established by dynamic testing with signal matching analysis. Based on the scour depth, and axial and lateral capacity requirements, we recommend maximum pile tip El. 536 at Fitzwater Abutment 1 (East), El. 522 at Fitzwater Abutment 2 (West), El. 510 at the Fitzwater Piers, El. 531 at Waste Weir Abutment 1 (East), El. 535 at Waste Weir Abutment 2 (West) and El. 527 the Waste Weir Pier.

A wave equation analysis of the contractor’s proposed hammer and driving system should be submitted to EFLHD’s Geotechnical Section for review prior to mobilization of the equipment to the site. The proposed hammer should have adequate energy to efficiently install the piles to the specified capacities without inducing excessive driving stresses.

We recommend that a minimum of one pile at each bridge substructure be dynamically load tested.

Additionally, we recommend including three additional tests (one at each pier) as a contingency.

Therefore, we recommend a total of 10 dynamic load tests (six for Fitzwater Bridge, four for Waste Weir Bridge). Test locations should be selected at a corner of each pile cap, and also at the center of the pile cap for piers. Signal matching analysis should be performed at two locations at each bridge, one at an abutment and one at a pier. We recommend that test piles have an additional 10 feet of length.

All dynamic testing is to be performed in accordance with Section 551 of the FP-03. We recommend a minimum center-to-center pile spacing of three pile widths.

Preoloading West Approach Embankment

The approach western approach embankment for the Fitzwater Bridge should be preloaded for a minimum of 2 months prior to driving piles for the west abutment. A surcharge load equivalent to 4 feet above proposed finished grade should be placed between Stations 105+00 and 105+50. One option is to use aggregate base course above the proposed finish grade. The surcharge material on the side slopes may consist of embankment fill. After the preload period is complete, the aggregate base may be used in other areas of the project, and the embankment side slopes should be trimmed to finished grade.

Temporary Bridge

The temporary bridge on Fitzwater Road to support equipment necessary for construction of the new bridges should be designed to bear on spread footings supported on reinforced structural fill. For strength limit state, use a nominal bearing resistance of 4,250 psf with a resistance factor of φb = 0.35, resulting in a factored resistance of 1,500 psf. At this loading, we calculated a settlement of approximately 2 inches. Because this bridge is a temporary structure that is designed to accommodate settlements, the service limit state resistance is calculated using a nominal bearing resistance of 1,500 psf with a resistance factor of φ = 1.0. To limit lateral pressure on the existing

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culvert walls, the footing for the temporary structure should be a minimum of 8 feet from the culvert sidewalls. At this distance, we estimate lateral pressures on the order of 40 psf. See Appendix E for design calculations.

ABUTMENT WALLS

The soil properties presented in Table 10 are recommended for the design of abutment walls. These parameters assume that select granular backfill material will be used for backfill.

Table 10 – Soil Design Parameters for Abutment Design

Parameter Value

Soil Unit Weight, γ (kcf) 0.120

Friction Angle, Φ (deg.) 32

Active Earth Pressure Coeff., Ka 0.31

Passive Earth Pressure Coeff., Kp 3.25

At-rest Earth Pressure Coeff., Ko 0.47

Coefficient of Sliding, Tan δ 0.35

Control hydrostatic pressures and seepage by placing free-draining material adjacent to the abutment walls in accordance with Section 208 of the FP-03 Specifications.

RETAINING WALL – GEOCELL WALL

The following recommendations are based on the results of the field and subsurface investigation conditions as they existed at the time of the field inspections, laboratory test results, and design analyses results. Based on stability analysis results we recommend that the retaining wall, proposed for support of embankment fills for the Towpath Trail, be comprised of a geogrid-reinforced embankment with geocell panels in the front.

Table 11 – Retaining Wall Configuration Max Height

(ft) Minimum Embedment

Depth (ft) Batter of Face

7.0 2.5 1(h):6(v)

Our subsurface field investigation indicates that the proposed retaining wall will likely bear on existing fill. Boring WB-2, drilled in the vicinity of the proposed retaining wall, indicates that existing soils are fill soils consisting of silt and clay to approximately Elevation 608 ft. Underlying the fill stratum is silt, sand and gravel.

Design analyses indicate that the proposed geocell wall meets global stability requirements. We recommend that the retaining wall be designed to bear on fill that has been proofrolled in accordance with FP-03 Standard Specifications. Additional recommendations for the geocell wall are as follows:

FITZWATER AND WASTE WEIR BRIDGES

Install 4.0-ft wide geocell panels from the base to the top of the wall

Provide 8.0-inch high geocell panels

Use 3 layers of geogrid at 2-ft. vertical spacing across the embankment.

Fill the outer cell of each geocell layer above the foundation with topsoil and seed mix

Fill the cells behind the outer cells with gravel to provide drainage

Install weep holes at 8.0 feet on-center at a minimum of 2.0 feet from the bottom of the wall as shown on the drawing in Appendix E.

Fill the remaining cells with granular soil fill. If encountered, the granular portion of on-site soils could be used to fill the cells. Compact the soil fill according to the FP-03 Standard Specifications.

To mitigate the potential for hydrostatic pressure buildup behind walls, the cells behind the front face will be filled with free-draining select granular fill.

Special Contract Requirements (SCR’s) pertaining to geotechnical items developed for this project are included in Appendix G.

PAVEMENT

The following pavement recommendations are based on the findings of our subsurface field investigation and laboratory testing.

The majority of pavement sections along the alignment will be constructed on fill embankments overlying the existing soil subgrade. Generally, fill embankments vary in height between 1.0 and 15.0 ft.

Fill, consisting of pavement and existing granular base material, and Lacustrine silt and clay, were encountered at ground surface along the length of the proposed alignment.

We recommend the following pavement section be constructed along Fitzwater Road.

Table 12 –Pavement Section

Layer Thickness (in.) Comments

SACP Surface Course

(in.)

1.5

Superpave Asphalt Concrete Pavement (SACP), <0.3 x 106 ESALs, 3/8-in. Nominal Maximum Size Aggregate (NMSA), Type III Smoothness

SACP Base Course

(in.)

2.5

Superpave Asphalt Concrete Pavement (SACP), <0.3 x 106 ESALs, 1/2-in. Nominal Maximum Size Aggregate (NMSA)

Aggregate Base Course 8 Aggregate Base, Grading C or D, ¾-in. NMSA

FITZWATER AND WASTE WEIR BRIDGES

All fill slopes should be constructed in accordance with Section 204 of the FP-03 and with side slope geometries of 1(V):2(H) or flatter.

CONSTRUCTION CONSIDERATIONS

Excavations: In general, all temporary cut slopes constructed in soils should not be steeper than 1 horizontal to 1 vertical (1H:1V), unless otherwise allowed by OSHA. All excavations are to be performed in accordance with applicable OSHA standards and in accordance with Section 204 of the FP- 03 Specifications. Temporary excavation in fill and/or natural material should be achievable using conventional earthmoving equipment in proper working condition. Any unsuitable materials encountered below proposed footing elevations should be removed.

The existing cohesive fill should be proofrolled and not disturbed. Excavations should not remain open for an extended period of time during construction operations. Appropriate drainage, access, and conditions for stability should be provided for all excavations.

Subgrade Preparation: Upon completion of excavation, the surface of the proposed foundation bearing layer should be prepared in accordance with Section 204. Proof rolling should be completed using a pneumatic-tired roller, dump truck, or other pneumatic-tired vehicle with an appropriate weight and tire pressure. The foundation bearing layer should be proof rolled for at least five passes. Proof rolled surfaces should be uniform, smooth, and free of abrupt changes in slope, debris, and irregularities that might damage the geogrid. If unsuitable materials are encountered in isolated areas, subexcavation and replacement of the unsuitable materials is recommended. Replacement materials should consist of compacted unclassified borrow in accordance with subsection 704.06. Subexcavation should be in accordance with subsection 204.07.

Structural Backfill: The on-site soils are not suitable for reuse as structural backfill behind bridge abutment walls or the retaining wall. Backfill behind abutment walls should consist of structural backfill in accordance with Section 704 of the FP-03 Specifications.

Backfill Drainage: For drainage of structural backfill behind retaining walls, provide weepholes with a 6-in. diameter through abutment walls, wingwalls, and retaining walls. Weepholes should be spaced a maximum of 8 ft on-center, and should be installed at a minimum 2.0 ft above the finished grade along the face of the structure. All weepholes should be approved non-perforated PVC pipes per Section 706 of the FP-03 Specifications. Approved geocomposite drains as per Section 714 should be placed against the backfilled face of the walls. The geocomposite drains should extend from the top of the weepholes to the bottom of the proposed aggregate base course at approaches.