17866 Alton Tannery Bridge Geotechnical Report Rev1 ...

MAINE DEPARTMENT OF TRANSPORTATION BRIDGE PROGRAM

GEOTECHNICAL SECTION AUGUSTA, MAINE

GEOTECHNICAL DESIGN REPORT

For the Superstructure Replacement and Abutment Rehabilitation of:

TANNERY BRIDGE

ALTON TANNERY ROAD OVER DEAD STREAM ALTON, MAINE

Prepared by: Brandon Slaven

Assistant Geotechnical Engineer

Laura Krusinski, P.E. Senior Geotechnical Engineer

Penobscot County Soils Report No. 2016-22 WIN 17866.00 Bridge No. 5100

July 18, 2016

Table of Contents

GEOTECHNICAL DESIGN SUMMARY ........................................................................... 1

1.0 INTRODUCTION....................................................................................................... 4

2.0 GEOLOGIC SETTING ............................................................................................. 5

3.0 SUBSURFACE INVESTIGATION .......................................................................... 5

4.0 LABORATORY TESTING ....................................................................................... 6

5.0 SUBSURFACE CONDITIONS ................................................................................. 6

5.1 FILL ........................................................................................................................... 6 5.2 GLACIAL TILL ............................................................................................................ 7 5.3 BEDROCK ................................................................................................................... 7 5.4 GROUNDWATER ......................................................................................................... 8

6.0 PROJECT ALTERNATIVES ................................................................................... 8

7.0 GEOTECHNICAL DESIGN RECOMMENDATIONS ......................................... 9

7.1 ABUTMENT REHABILITATION AND REUSE ................................................................. 9 7.1.1 SLIDING ..................................................................................................................... 9 7.1.2 BEARING RESISTANCE AND ECCENTRICITY .............................................................. 10 7.1.3 ABUTMENT EARTH PRESSURES AND LIVE LOAD SURCHARGE ................................. 11 7.1.4 DEADMAN AND TIE-ROD DESIGN ............................................................................ 12 7.1.5 GLOBAL STABILITY ................................................................................................. 12 7.2 FROST PROTECTION ................................................................................................. 13 7.3 SCOUR AND RIPRAP ................................................................................................. 13 7.4 SEISMIC DESIGN CONSIDERATIONS .......................................................................... 14 7.5 CONSTRUCTION CONSIDERATIONS ........................................................................... 15

8.0 CLOSURE ................................................................................................................. 15

Tables ___ ______ Table 1 – Summary of Approximate Bedrock Depths and Elevations Table 2 – Resistance Factors for Sliding Table 3 – Maximum Coefficients of Friction for Sliding Table 4 – Bearing Resistances Table 5 – Eccentricity Limits Table 6 – Equivalent Height of Soil for Estimating Live Load Surcharge on Abutments Table 7 – Seismic Design Parameters

Sheets Sheet 1 – Location Map Sheet 2 – Boring Location Plan and Interpretive Subsurface Profile Sheet 3 – Boring Logs Appendices Appendix A – Boring Logs Appendix B – Laboratory Test Results Appendix C – Calculations

Tannery Bridge Alton, Maine

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GEOTECHNICAL DESIGN SUMMARY The purpose of this Geotechnical Design Report is to present subsurface information and provide geotechnical design recommendations for the rehabilitation of the existing granite block and concrete abutments, removal of the existing bridge pier, and placement of scour countermeasures at Tannery Bridge which carries Tannery Road over Dead Stream in Alton, Maine. The replacement superstructure will be a single-span prefabricated unit to be designed and supplied by the contractor in accordance with a “detail-build” project specification. The following design recommendations are discussed in detail in this report: Abutment Rehabilitation and Reuse – The rehabilitation of the existing abutments will consist of:

• Removal of the existing backwall at Abutment No. 2. • Installation of prefabricated sheet pile backwalls at both abutments. • Concrete repair of soft or spalled areas on abutments. • Improving the stability of the abutments with deadman and tie-rod systems. • Repair of undermining at the abutment spread footings with grout bags. • Installation of scour countermeasures.

The existing abutments should be evaluated to ensure that they meet current AASHTO LRFD Bridge Design Specifications, 7th Edition, 2014 (LRFD) standards for sliding, eccentricity, bearing resistance, and stability. The demand on the existing abutments will increase due to the removal of the center pier and replacement of the superstructure. The rehabilitated abutments shall be proportioned of all applicable load combinations specified in LRFD and be evaluated for all relevant strength, extreme, and service limit states. Sliding – The existing abutments are founded on spread footings on native silt. Resistance factors for sliding analyses for both abutments are provided in Section 7.1.1, Table 2. Maximum friction coefficients for sliding analyses for both abutments are provided in Section 7.1.1, Table 3. Bearing Resistance and Eccentricity – The existing abutments should be evaluated to ensure that they will meet current LRFD standards against bearing capacity failure after superstructure replacement and abutment rehabilitation. Application of permanent and transient loads is specified in LRFD. The stress distribution at the abutments may be assumed to be a linearly distributed pressure over the effective base. The bearing resistances for the existing abutments for all limit states are presented in Section 7.1.2, Table 4. The eccentricity limits for the abutments are presented in Section 7.1.2, Table 5. Earth Pressures and Surcharge Forces – Modifications to the existing abutments and wingwalls should be designed for active earth pressure over the height of the walls. A Coulomb active earth pressure coefficient, Kac, of 0.28 is recommended assuming level backfill. The resultant earth pressure is orientated at an angle of δ from a perpendicular line to the wall backface, where δ is the angle of friction between the abutment backfill soil and


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the wall backface. The designer may assume backfill soil properties as follows: ϕ = 32 degrees, γ = 125 pcf. If the abutments and wingwalls are stabilized with deadman and tie-rod systems, the wall movement will be significantly less that that required to develop active pressure and the design should use an at-rest earth pressure coefficient, Ko, of 0.47. Additional lateral earth pressure due to construction surcharge or live load surcharge is required for the abutments and wingwalls if an approach slab is not specified. If a structural approach slab is specified, some reduction of surcharge loads is permitted. Deadman and Tie-Rod Design – Deadman and tie-rod systems may be included in the design modifications to both abutments to provide additional resistance to lateral earth pressures, proposed dead load demands, and live loads. Deadmen may consist of steel anchor plates, beams, or concrete blocks. Tie-rod steel may be Grade 75 or 150 depending on the bar diameter and the nominal design resistance of each deadman. For calculating the net ultimate resistance of the deadman in the backfill soils, use an active Rankine earth pressure coefficient, Ka, of 0.32, a Rankine passive pressure coefficient, Kp, of 3.26 and a resistance factor, φep, of 0.50 for passive earth pressures. Deadmen and tie-rods shall be embedded below the calculated depth of frost of 7.5 feet. The deadmen shall be located behind the abutments outside of the active and passive earth pressure zones. This will require construction of deadmen approximately 26 feet behind the face of the existing abutments. Global Stability – Global stability analyses were performed for the proposed abutment re-use. The analyses were performed at Abutment No. 2, which was identified as the critical section. The calculated factor of safety is 1.5 which meets the minimum LRFD factor of safety without additional margin. Incorporation of a deadman and tie-rod system in the abutment modifications will increase the factor of safety for global stability of the abutments to approximately 1.8. Frost Protection – Foundations and deadman and tie-rod systems should be founded a minimum of 7.5 feet below finished exterior grade for frost protection. Riprap is not to be considered as contributing to the overall thickness of soils required for frost protection. Scour and Riprap – Spread footings on soil shall be located so that the bottom of the footings are below the scour depths determined for the design and check floods. Repair of abutment undermining with grout bags and installation of scour countermeasures is required. Scour countermeasures may consist of precast concrete cable mats or riprap. Plain riprap shall conform to MaineDOT Standard Specification 703.26. The toe of the riprap section shall be constructed 1 foot below the streambed elevation. The riprap section shall be underlain by a 1 foot thick layer of bedding material and Class 1 nonwoven erosion control geotextile. The contractor’s work in the streambed to install scour countermeasures shall not undermine or destabilize the existing abutment and wingwall spread footings.


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Seismic Design Considerations – The proposed Tannery Bridge is a single span structure in Seismic Zone 1; therefore, no consideration for seismic forces is required except that superstructure connections and minimum support length requirements shall be satisfied. Construction Considerations – Rehabilitation of the existing abutments will require removal of a concrete backwall at Abutment No. 2 and partial removal of the roadway approach fills. Construction activities may include installation of deadman and tie-rod systems to improve the stability of the existing abutments. Construction activities will include removal of the existing pier down to the streambed. Pier removal activities shall be conducted with care so not to disturb, undermine, or compromise the existing abutment foundations to remain. This should be noted on the Plans. Construction activities will also include installation of scour countermeasures and repairing undermining at the abutment and wingwall footings. These activities shall be conducted with care so not to disturb, undermine, or compromise the existing abutment and wingwall footings. This should be noted on the Plans. Construction activities may encounter saturated roadway approach fill soils and water seepage may occur. There may be localized sloughing and surface instability in some soil slopes. The contractor should control groundwater, surface water infiltration, and soil erosion during construction.


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1.0 INTRODUCTION The purpose of this Geotechnical Design Report is to present subsurface information and provide geotechnical design recommendations for the rehabilitation of the existing granite block and concrete abutments, removal of the existing bridge pier, and placement of scour countermeasures at Tannery Bridge. Tannery Bridge carries Alton Tannery Road over Dead Stream in Alton, Maine. This report presents the subsurface information obtained at the site during the subsurface investigation, geotechnical design and foundation rehabilitation recommendations, and construction considerations. The existing two span Tannery Bridge was constructed in 1928. The structure is comprised of an approximately 24 foot long concrete slab connected to a 40 foot long steel plate girder at an offset from center pier. The pier consists of approximately 3 courses of mortared granite blocks, capped by reinforced concrete, bearing on a 3 foot thick concrete spread footing founded on soil. The abutments consist of granite blocks capped by unreinforced concrete; the battered backslope of the abutment and wingwalls are constructed of concrete. The abutment foundations also consist of 3 foot thick concrete spread footings bearing on soil. The 2014 Maine Department of Transportation (MaineDOT) Bridge Maintenance inspection report assigns the substructure a condition rating of 6 – satisfactory, the deck a 4 – poor, and the superstructure a 3 – serious. The deteriorated condition of the superstructure warranted posting of limited traffic loads on the structure and requires reevaluation every six months. The current structure is listed as Structural Deficient and has a Structural Rating of 29.2 out of a possible 100. The MaineDOT Bridge Program originally scoped this project as a complete replacement. A visual inspection of the abutments by a team from the Bridge Program resulted in a determination that the abutments were in “satisfactory condition” and contained adequate service life to warrant rehabilitation. Rehabilitation will include deadman and tie-rod systems at the abutments to help meet current AASHTO Load Resistance Factor Design (LRFD) requirements for stability and strength, concrete repair of soft and spalled areas, and scour countermeasures to protect the foundations on soil. The existing pier will be removed. The replacement superstructure will be a single-span prefabricated unit to be designed and supplied by the contractor in accordance with a “detail-build” project specification. The replacement superstructure is expected to have a 62-foot 4-inch clear span. The vertical profile across the new structure will be raised 1 to 1.5 feet to match existing conditions. This raise in grade will require approximately 250 feet of approach work. The rehabilitated bridge will accommodate one (1) 14 foot lane and have a total width of approximately 16 feet. Closure of the existing bridge and Tannery Road will allow for construction of the new superstructure and rehabilitation of the substructures in one construction season.


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2.0 GEOLOGIC SETTING Tannery Bridge in Alton, Maine crosses Dead Stream as shown on Sheet 1 – Location Map. The Maine Geological Survey (MGS) Surficial Geology Map of the Boyd Lake Quadrangle, Maine, Open-file No. 81-5 (1981), indicates the surficial soils in the vicinity of the bridge project consist of swamp and tidal-marsh deposits with nearby contacts to glaciomarine deposits. Swamp and tidal-marsh deposits generally consist of peat, silt, clay, and sand that accumulate in depressions and other poorly drained areas. Glaciomarine deposits, known locally as the Presumpscot Formation, generally consist of clay and silt that washed out of the Late Wisconsinan glacier and accumulated on the ocean floor when the relative sea level was higher than at present. The Bedrock Geologic Map of Maine, MGS (1985), cites the bedrock at the project site as a calcareous sandstone interbedded with sandstone and impure limestone and part of the Waterville Formation.

3.0 SUBSURFACE INVESTIGATION Subsurface conditions at the site were explored by drilling four test borings. Boring BB-ADS-101 was drilled behind the existing Abutment No. 1. Borings BB-ADS-102 and BB-ADS-102A were drilled behind the existing Abutment No. 2. Boring BB-ADS-103 was drilled through the existing pier. The test boring locations are shown on Sheet 2 – Boring Location Plan and Interpretive Subsurface Profile. The test borings were drilled between August 15 and 17, 2011 by the Maine Test Boring (MTB) of Hermon, Maine. All borings were performed using solid stem auger, cased wash boring, and rock coring techniques. Soil samples were typically obtained at 5-foot intervals using Standard Penetration Test (SPT) methods. During SPT sampling, the split spoon sampler is driven 24 inches and the hammer blows for each 6-inch interval of penetration are recorded. The sum of the blows for the second and third intervals is the N-value, or standard penetration resistance. The MTB drill rig is equipped with an automatic hammer to drive the split spoon sampler. The automatic hammer was calibrated per ASTM D4633 “Standard Test Method for Energy Measurement for Dynamic Penetrometers” in September of 2011. All N-values discussed in this report are corrected values computed by applying the corresponding average energy transfer factor of 0.783 to the raw field N-values. The hammer efficiency factor (0.783) and both the raw field N-values and the corrected N-values are shown on the boring logs provided in Appendix A – Boring Logs and on Sheet 3 – Boring Logs. Bedrock was cored in the three of the four borings using an NQ-2” or HQ-2” wireline core barrel and the Rock Quality Designation (RQD) of the cores calculated. A Northeast Transportation Technician Certification Program (NETTCP) Certified Subsurface Inspector logged the subsurface conditions encountered. The MaineDOT geotechnical engineer selected the boring locations and drilling methods, designated type and depth of sampling


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techniques, reviewed draft boring logs, and identified field and laboratory testing requirements. The borings were located in the field by use of a tape after completion of the exploration program. Details and sampling methods used, field data obtained, and soil and groundwater conditions encountered are presented on the boring logs provided in Appendix A – Boring Logs, Sheet 3 – Boring Logs, and graphically on Sheet 2 – Boring Location Plan & Interpretive Subsurface Profile.

4.0 LABORATORY TESTING A laboratory testing program was conducted on selected soil samples recovered from test borings to assist in soil classification, evaluation of engineering properties of the soils, and geologic assessment of the project site. Soil laboratory testing consisted of eight (8) standard grain size analyses with natural water content detrminations. The results of soil laboratory tests are included as Appendix B – Laboratory Test Results. Laboratory test information is also shown on the boring logs provided in Appendix A – Boring Logs and on Sheet 3 – Boring Logs.

5.0 SUBSURFACE CONDITIONS Subsurface conditions encountered in the borings generally consisted of granular fill and glacial till underlain by metamorphic sedimentary bedrock. The boring logs are provided in Appendix A – Boring Logs and on Sheet 3 – Boring Logs. A generalized subsurface profile is shown on Sheet 2 – Boring Location Plan and Interpretive Subsurface Profile. The following paragraphs discuss the subsurface conditions encountered:

5.1 Fill A layer of fill was encountered in borings BB-ADS-101, BB-ADS-102 and BB-ADS-102A. The fill unit is approximately 9.6 to 10.5 feet thick at the boring locations. The fill material encountered generally consisted of:

Brown, gravelly sand, little silt; Brown, gravel, little sand, little silt; Grey-brown, silty, fine to medium sand, little gravel.

A wood layer was encountered at approximately Elev. 120 in borings BB-ADS-101 and BB-ADS-102. Cobbles were encountered above the wood layer in BB-ADS-102 and encountered frequently between 2.8 and 5.1 feet below ground surface (bgs) in BB-ADS-101. BB-ADS-102A reached a depth of 3.5 feet bgs and was abandoned when it refused on what is assumed to be a boulder.


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Corrected SPT N-values in the fill materials ranged from 10 to >50 blows per foot (bpf) indicating that fill layer is loose to very dense in consistency. Two (2) grain size analyses of the fill soils resulted in the soil being classified as A-1-a or A-1-b under the AASHTO Soil Classification System and SW-SM or SM under the Unified Soil Classification System (USCS). The natural water content of the samples tested ranged from approximately 3 to 4 percent.

5.2 Glacial Till A deposit of glacial till was encountered below the fill unit and below the existing pier. The thickness of the glacial till deposit ranged from approximately 10.4 to 17.8 feet at the boring locations. The upper glacial till deposit encountered generally consisted of:

Grey, silt, some sand, little to some gravel. The lower glacial till deposit consisted of:

Grey, sand, some silt, little gravel; Grey, silty, fine to medium sand, little gravel.

Corrected SPT N-values in the glacial till deposit ranged from 37 to >50 bpf indicating the till is hard or dense to very dense in consistency. Five (5) grain size analyses of the glacial till deposit resulted in the soils being classified as A-4 or A-2-4 under the AASHTO Soil Classification System and ML or SM under the USCS. The moisture contents of the tested samples ranged from approximately 7 to 11 percent.

5.3 Bedrock Bedrock was encountered and cored in three of the four test borings. Table 1 summarizes approximate depths to bedrock, corresponding approximate top of bedrock elevations and RQD.


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Boring

Station

Offset (feet)

Approximate Depth to Bedrock

(feet)

Approximate Elevation of Weathered Bedrock Surface1

(feet)

Approximate Elevation of

Intact Bedrock Surface1

(feet)

RQD (Core Run)

BB-ADS-101 6+90.2 0.4 ft Lt 27.4 102.50 99.5 80% (R1) 70% (R2)

BB-ADS-102 7+78.3 1.5 ft Rt 21.8 108.70 106.5 30% (R1) 34% (R2)

BB-ADS-103 7+22.3 0.5 ft Lt 23.2 n.a. 107.2 0% (R4)

18% (R5)

Table 1 – Summary of Approximate Bedrock Depths and Elevations The bedrock at the site is identified as black and grey, fine grained, banded slate, soft to moderately hard, slight to moderate weathering, zones of slatey cleavage and steep dipping slaty partings, intact joints are moderate to steeply dipping, very close to close, occasionally healed with quartz and calcite infilling. The RQD of the bedrock was determined to range from 0 to 80 percent correlating to a Rock Mass Quality of very poor to good. Detailed bedrock descriptions and the RQD of each core run are provided on the boring logs on Sheet 3 – Boring Logs and in Appendix A – Boring Logs.

5.4 Groundwater Groundwater was measured between approximately 7.0 and 9.8 feet bgs in the test borings. The water levels measured upon completion of drilling are indicated on the boring logs found in Appendix A. Note that water was introduced into the boreholes during the drilling operations. Therefore, the water levels indicated on the boring logs may not represent stabilized groundwater conditions. Groundwater levels will fluctuate with changes in water levels in the river, seasonal changes, precipitation, runoff, and construction activities.

6.0 PROJECT ALTERNATIVES The project was originally scoped as a bridge replacement project. During development of the Preliminary Design Report (PDR), the abutments were visually inspected by a team from the Bridge Program and sounded with a hammer to determine the integrity of the existing concrete. The inspection of the abutments resulted in a determination that the abutments were in “satisfactory condition” and contained adequate service life to warrant rehabilitation. Rehabilitation of the abutments will include a deadman and tie-rod system to help meet current AASHTO LRFD requirements for stability and strength, and scour countermeasures to protect the foundations on soil. The existing pier will be removed. The replacement

1 Elevations based off NAVD 1988


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superstructure will be a single-span prefabricated unit to be designed and supplied by the contractor in accordance with a “detail-build” project specification.

7.0 GEOTECHNICAL DESIGN RECOMMENDATIONS The following subsections provide geotechnical recommendations, geotechnical design parameters, and construction recommendations for the rehabilitation of the existing mortared stone and concrete abutments, removal of the existing pier, and installation of scour countermeasures. The design recommendations in this Section are in accordance with AASHTO LRFD Bridge Design Specifications 7th Edition, 2014 (LRFD) and MaineDOT Bridge Design Guide (BDG) Section 10.6 – Substructure Rehabilitation, and BDG Section 10.7 – Substructure Reuse.

7.1 Abutment Rehabilitation and Reuse The rehabilitation of the existing abutments will consist of:

Removal of the existing backwall at Abutment No. 2. Installation of prefabricated sheet pile backwalls at both Abutments. Repair of soft or spalled areas of concrete. Improving the stability of the Abutments with deadmen and tie-rods. Repair of undermining at the abutment spread footings with grout bags. Installation of scour countermeasures.

The existing abutments should be evaluated to ensure they meet current LRFD standards for sliding, eccentricity, bearing resistance, and stability. The demand on the existing abutments will increase due to the removal of the center pier and replacement of the superstructure. The rehabilitated abutments shall be proportioned for all applicable load combinations specified in LRFD Articles 3.4.1 and 11.5.5 and be evaluated for all relevant strength, extreme, and service limit states. LRFD Figures C11.5.6-1 and C11.5.6-2 illustrate the typical load factors to produce the extreme factored effect for bearing resistance, sliding, and eccentricity.

7.1.1 Sliding Based on the historical bridge plans and the borings conducted at the site it is assumed that the existing abutments are founded on unreinforced concrete footings bearing on native soil. Table 2 presents resistance factors, φτ, for sliding analyses.


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Substructure Assumed Bearing Material

Condition Limit State

Sliding Resistance Factor, φτ

LRFD Reference

Abutment No. 1 and No. 2

Silt (Glacial Till)

Concrete on silt

Strength 0.8 Table 10.5.5.2.2-1 Service 1.0 Article 10.5.5.1 Extreme 1.0 Article 10.5.5.3

Table 2 – Resistance Factors for Sliding

Passive earth pressure due to streambed soils or riprap in front of abutment footings shall be neglected in the sliding analyses. The sliding resistance of the abutment footings to lateral loads shall be calculated using the maximum coefficients of friction provided in Table 3:

Substructure Interface Materials

Limit State

Friction Angle, δ

Coefficient of Friction, Tan δ

(dim.) LRFD Reference


Concrete/Silt All 17° .31 Table 3.11.5.3-1

Table 3 – Maximum Coefficients of Friction for Sliding

7.1.2 Bearing Resistance and Eccentricity

Based on the historical bridge plans and the borings conducted at the site it is assumed that the existing abutments are founded on native soil. The existing abutments should be checked to ensure that they meet current LRFD standards against bearing capacity failure after superstructure replacement and abutment rehabilitation. Effective footing dimensions are specified in LRFD Article 10.6.1.3 and the application of permanent and transient loads should be as stated in LRFD Article 11.5.6. The stress distribution at the abutments may assume a linear distribution of pressure over the effective base as shown in LRFD Figure 11.6.3.2-1. Table 4 summarizes the resistance factors and bearing resistances for the existing abutments. Supporting documentation is provided in Appendix C – Calculations.


Limit State Resistance Factor, φb

Factored Bearing

Resistance (ksf)

LRFD Reference


Silt (Glacial Till)

Strength 0.45 5.8 Table 10.5.5.2.2 Service 1.0 6 Article 10.5.5.1 Extreme 1.0 13 Article C11.5.8


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Table 4 – Bearing Resistances

LRFD Figures C11.5.6-1 and C11.5.6-2 (2015 Interim Revisions) illustrate the typical load factors at the strength limit state to produce the extreme factored effect for evaluating eccentricity. LRFD Figure C.11.5.6-4 (2015 Interim Revisions) illustrates the typical load factors at the Extreme Event I limit state for evaluating eccentricity. The eccentricity limits are presented in Table 5:


Location of Resultant Forces

LRFD Reference


Silt (Glacial Till)

Within the middle two-thirds (2/3) of the

base width Article 11.6.3.3

Table 5 – Eccentricity Limits

7.1.3 Abutment Earth Pressures and Live Load Surcharge

Modification to the existing abutments and wingwalls should be designed for active earth pressure over the wall height. Coulomb wedge theory applies for gravity and semi-gravity walls. In designing for active pressure, a Coulomb active earth pressure coefficient, Kac, of 0.28 is recommended assuming level backfill. The resultant earth pressure is orientated at an angle, δ, from a perpendicular line to the wall backface. The angle δ is the angle of friction between the abutment backfill soil and the wall backface. If the abutments and wingwalls are stabilized with deadman and tie-rod systems, the wall movement will be significantly less than that required to develop active pressure and the design should consider at-rest conditions and assume an at-rest earth pressure coefficient, Ko, of 0.47. Supporting calculations are provided in Appendix C – Calculations. Additional lateral earth pressure due to construction surcharge or live load surcharge is required per Section 3.6.8 of the MaineDOT BDG for abutments if an approach slab is not specified. When a structural approach slab is specified reduction, not elimination, of the surcharge load is permitted per LRFD Article 3.11.6.5. The live load surcharge may be estimated as a uniform horizontal earth pressure due to an equivalent height of soil (heq) taken from Table 6:


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Abutment Height (feet)

heq

(feet) 5 4.0 10 3.0 ≥20 2.0

Table 6 – Equivalent Height of Soil for Estimating Live Load Surcharge on Abutments Abutment modifications should ensure drainage of water behind the structure to prevent development of hydrostatic and seepage forces. If backfill material behind the abutment is not allowed to drain, the effect of hydrostatic water pressure must be added to that of earth pressure.

7.1.4 Deadman and Tie-Rod Design Deadman and tie-rod systems may be included in the design modifications to both abutments to provide additional resistance to lateral earth pressures, proposed dead load demands (due to removal of the center pier and replacement of the superstructure), and live loads. Deadmen may consist of steel anchor plates, beams, or concrete blocks. Tie-rod steel may be Grade 75 or 150 depending on the bar diameter and the nominal design resistance of each deadman. A corrosion rate consistent with the design life of the structure should be considered in the design of steel components or corrosion protection of steel components provided. The resistance provided by deadman plates, beams, or blocks is derived from the passive force of the soil located in front of them. Resisting earth pressure engaged by a deadman may use a Rankine passive pressure coefficient, Kp, of 3.26 and a resistance factor, φep, of 0.50. Surcharge loads should not be applied to increase the resisting earth pressure. For calculating the net ultimate resistance of the deadman in the backfill soils, use an active Rankine earth pressure coefficient, Ka, of 0.32. Deadmen and tie-rods shall be embedded below the calculated depth of frost of 7.5 feet. The deadmen shall be located behind the abutments such that the active earth pressure zone of the abutment and passive earth pressure zone engaged by the deadmen do not intersect. We estimate this will require construction of deadmen approximately 26 feet behind the face of the existing abutments.

7.1.5 Global Stability Global stability analyses were performed for the proposed abutment re-use using Service I Load Combinations. The analyses were performed at Abutment No. 2 which was chosen as the critical case with respect to the riverbed profile. The load combinations assumed a steel superstructure with two deck alternatives. One deck alternative was a comparatively lighter weight corrugated steel deck infilled with hot-mix asphalt. The other deck consisted of a concrete composition resulting in larger dead loads placed on the abutment. The results of


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the stability analyses indicate that both superstructure and deck alternatives result in a factor of safety of 1.5, corresponding to the minimum required factor of safety of 1.5 (equivalent to a LRFD resistance factor of 0.65.) Deadman and tie-rod systems may be included in the design modifications to improve the sliding and overturning resistance of the existing abutments in response to increased dead and live load demands. An additional global stability analysis was conducted to determine the benefit of a deadman system providing approximately 5.6 kips of additional resisting force per linear foot. The results of the analysis indicates that the deadman system increases the factor of safety for global stability from the minimum requirement of 1.5 to approximately 1.8.

7.2 Frost Protection Foundations placed on soil should be designed with an appropriate embedment for frost protection. Deadmen and tie-rods should also be embedded for frost protection. According to BDG Figure 5-1, Maine Design Freezing Index Map, Alton has a design freezing index of approximately 1850 F-degree days. An assumed water content of 10% was used for coarse grained soils. These components correlate to a frost depth of approximately 7.6 feet. A similar analysis was performed using Modberg software by the US Army Cold Regions Research and Engineering Laboratory (CRREL). For the Modberg analysis, Alton was assigned a design freezing index of approximately 1588 F-degree days, for Orono, the closest location in the Modberg database. An assumed water content of 10% was used for coarse grained fill soils above the water table. These components correlate to a frost depth of approximately 7.4 feet. Based on an average of these results, it is recommended foundations be designed with an embedment of approximately 7.5 feet for frost protection. See Appendix C – Calculations for supporting documentation. Riprap is not to be considered as contributing to the overall thickness of soils required for frost protection.

7.3 Scour and Riprap Grain size analyses were performed on soil samples of the glacial till deposit to generate grain size curves for determining parameters to be used in scour analyses. The samples were assumed to be similar to the soils to be encountered in the streambed and at the base of the existing abutments. The following averaged grain size parameters can be used to perform scour analyses:

Average diameter of particle at 50 percent passing, D50 = 0.05 mm (silt) Average diameter of particle at 95 percent passing, D95 = 21.7 mm (medium gravel)

The grain size curves are included in Appendix B – Laboratory Test Results.


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In accordance with LRFD, spread footings on soil shall be located so that the bottom of the footing is below the scour depths determined for the design flood (Q100 event) and the check flood (Q500 event). Design at the strength limit state should also consider loss of lateral and vertical support due to scour; design at the extreme event limit state (EE II) should check that the nominal foundation resistance due to the check flood is not less that the EE II loads. Maintenance records indicate undermining of the abutments and previous installations of grout bags. At a minimum, rehabilitation of the existing abutments should include repair of any residual undermining and installation of scour countermeasures, such as precast concrete cable mats. For scour protection of bridge approach slopes, slopes shall be armored with 3 feet of riprap. Plain riprap shall conform to MaineDOT Standard Specification 703.26. The toe of the riprap section shall be constructed 1 foot below the streambed elevation. The riprap section shall be underlain by a 1 foot thick layer of bedding material conforming to item number 703.19 of the Standard Specification and Class 1 nonwoven erosion control geotextile per Standard Details 610(02) through 610(04). Refer to MaineDOT BDG Section 2.3.11 for additional information regarding scour design. The contractor’s work in the streambed to install scour countermeasures shall not undermine or otherwise threaten the stability of the existing abutment and wingwall footings. Dredge generated from the installation of scour countermeasures shall be beneficially reused on site or disposed of according to environmental requirements.

7.4 Seismic Design Considerations The United States Geological Survey Seismic Design CD (Version 2.1), provided with the LRFD Manual, and LRFD Articles 3.10.3.1 and 3.10.6 were used to develop parameters for seismic design. Based on site coordinates, the software provided the recommended AASHTO Response Spectra for a 7 percent probability of exceedance in 75 years. These results are summarized in Table 7:

Parameter Design Value

Peak Ground Acceleration (FPGA) 1.20g Acceleration Coefficient (AS) 0.084g

SDS (Period = 0.2 sec) 0.181g SD1 (Period = 1.0 sec) 0.077g

Site Class C Seismic Zone 1

Table 7 – Seismic Design Parameters

In conformance with LRFD Article 4.7.4 seismic analysis is not required for bridges in Seismic Zone 1 or single-span bridges regardless of seismic zone. However, superstructure connections and minimum support length requirements shall be designed per LRFD Articles 3.10.9.2 and 4.7.4.4, respectively.


WIN 17866.00

15

See Appendix C – Calculations for supporting documentation.

7.5 Construction Considerations Rehabilitation of the existing abutments will require removal of the concrete backwall at Abutment No. 2 and partial removal of the roadway approach fills. Construction activities may include installation of deadman and tie-rod systems to improve the stability of the existing abutments. Construction activities will include removal of the existing pier to the streambed. Pier removal activities shall be conducted with care so not to disturb, undermine, or compromise the existing abutment foundations. This should be noted on the Plans. Construction activities will also include limited installation of scour countermeasures and repair of any residual undermining of the abutments. The activities shall be conducted with care so not to disturb or compromised the stability of the existing abutment and wingwall spread footings to remain. This should be noted on the Plans. Excavations for the abutment rehabilitation in the approach fills will expose soils that may become saturated and water seepage may occur during construction. There may be localized sloughing and surface instability in some excavations and cut slopes. The contractor should control groundwater, surface water infiltration, and soil erosion. Water should be controlled by pumping from sumps.

8.0 CLOSURE This report has been prepared for use by the MaineDOT Bridge Program for the specific application of the proposed superstructure replacement and abutment rehabilitation of Tannery Bridge in Alton, Maine in accordance with generally accepted geotechnical and foundation engineering practices. No other intended use or warranty is expressed or implied. In the event that any changes in the nature, design, or location of the proposed project are planned, this report should be reviewed by a geotechnical engineer to assess the appropriateness of the conclusions and recommendations and to modify the recommendations as appropriate to reflect the changes in design. Further, the analyses and recommendations are based in part upon limited soil explorations at discrete locations completed at the site. If variations from the conditions encountered during the investigation appear evident during construction, it may also become necessary to re-evaluate the recommendations made in this report. It is also recommend that the geotechnical engineer be provided the opportunity for a general review of the final design and specifications in order that the earthwork and foundation recommendations may be properly interpreted and implemented in the design.

Sheets

Map Scale 1:24000

The Maine Department of Transportation provides this publication for information only. Reliance upon this information is at user risk. It is subject to revisionand may be incomplete depending upon changing conditions. The Department assumes no liability if injuries or damages result from this information. Thismap is not intended to support emergency dispatch. Road names used on this map may not match official road names.

The Maine Department of Transportation provides this publication for information only. Reliance upon this information is at user risk. It is subject to revision and may be incomplete depending upon changingconditions. The Department assumes no liability if injuries or damages result from this information. This map is not intended to support emergency dispatch. Road names used on this map may not match officialroad names.

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Project Location

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Location Map Tannery Bridge #5100 carries Tannery Road over Dead Stream Alton, Maine Penobscot County WIN 17866.00 Federal No. BR-1786(600)X USGS 7.5' Series Topographic South Lagrange Quadrangle DeLORME Map 33, Grid 2D

Appendix A

Boring Logs

0

5

10

15

20

25

1D

2D

3D

4D

5D

24/17

24/6

24/16

24/18

24/15

0.50 - 2.50

5.00 - 7.00

10.00 - 12.00

15.00 - 17.00

20.00 - 22.00

15/18/19/16

13/3/5/18

13/13/25/37

16/14/18/19

13/17/11/14

37

8

38

32

28

48

10

50

42

37

SSA

SPUNAHEAD

OPENHOLE

a6

18

15

59

42

68

105

75

129.53

123.90

120.30

105.90

4½" PAVEMENT.0.38

Brown, damp, dense, Gravelly SAND, little silt, (Fill).

2"-5" Cobbles from 2.8-4.1 ft bgs.

Boulder from 4.1-5.1 ft bgs.

6.00Grey-brown, wet, loose, Silty, fine to medium SAND, little gravel, (Fill)

Wood layer from 9.2-9.6 ft bgs.9.60

Grey, wet, hard, SILT, some fine to coarse sand, little gravel, (GlacialTill).

Similar to above.Roller Coned ahead to 18.5 ft bgs.

a6 blows for 0.5 ft.Drove Casing to 20.0 ft bgs.Changed to NW Casing at 18.5 ft bgs.

Similar to above.Roller Coned ahead to 25.0 ft bgs.

Cobble from 23.2-23.6 ft bgs.

24.00

G#261751A-1-a, SW-SM

WC=2.5%

G#261752A-4, ML

WC=10.6%

Maine Department of Transportation Project: Tannery Bridge #5100 carries Tannery Roadover Dead Stream

Boring No.: BB-ADS-101Soil/Rock Exploration Log

Location: Alton, MaineUS CUSTOMARY UNITS WIN: 17866.00

Driller: Maine Test Boring, Inc. Elevation (ft.) 129.9 Auger ID/OD: 5" Solid Stem

Operator: Potter/Francis Datum: NAVD88 Sampler: Standard Split Spoon

Logged By: B. Wilder Rig Type: Mobile B53 Track Hammer Wt./Fall: 140#/30"

Date Start/Finish: 8/15/11; 07:30-16:00 Drilling Method: Cased Wash Boring Core Barrel: NQ-2"

Boring Location: 6+90.2, 0.4 ft Lt. Casing ID/OD: HW & NW Water Level*: 9.8 ft bgs.

Hammer Efficiency Factor: .783 Hammer Type: Automatic Hydraulic Rope & Cathead Definitions: R = Rock Core Sample Su = Insitu Field Vane Shear Strength (psf) Su(lab) = Lab Vane Shear Strength (psf)D = Split Spoon Sample SSA = Solid Stem Auger Tv = Pocket Torvane Shear Strength (psf) WC = water content, percentMD = Unsuccessful Split Spoon Sample attempt HSA = Hollow Stem Auger qp = Unconfined Compressive Strength (ksf) LL = Liquid LimitU = Thin Wall Tube Sample RC = Roller Cone N-uncorrected = Raw field SPT N-value PL = Plastic LimitMU = Unsuccessful Thin Wall Tube Sample attempt WOH = weight of 140lb. hammer Hammer Efficiency Factor = Annual Calibration Value PI = Plasticity IndexV = Insitu Vane Shear Test, PP = Pocket Penetrometer WOR/C = weight of rods or casing N60 = SPT N-uncorrected corrected for hammer efficiency G = Grain Size AnalysisMV = Unsuccessful Insitu Vane Shear Test attempt WO1P = Weight of one person N60 = (Hammer Efficiency Factor/60%)*N-uncorrected C = Consolidation Test

Remarks:

Auto Hammer #20

Stratification lines represent approximate boundaries between soil types; transitions may be gradual.

* Water level readings have been made at times and under conditions stated. Groundwater fluctuations may occur due to conditions otherthan those present at the time measurements were made. Boring No.: BB-ADS-101

Dep

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.)

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Visual Description and Remarks

LaboratoryTesting Results/

AASHTO and

Unified Class.

Page 1 of 2

25

30

35

40

45

50

6D

R1

R2

10.8/8

60/60

60/57

25.00 - 25.90

30.40 - 35.40

35.40 - 40.40

35/50(4.8")

RQD = 80%

RQD = 70%

--- 47

28

b150

NQ-2

102.50

99.50

89.50

Grey, wet, very dense, fine to coarse SAND, some silt, little gravel,(Glacial Till).

b150 blows for 0.4 ft.27.40

Weatherd ROCK.Roller Coned ahead to 30.4 ft bgs.Casing bounced.

30.40Top of Intact Bedrock at Elev. 99.5 ft.R1: Bedrock: Black and grey, fine grained, banded SLATE, soft, fresh toslightly weathered, joints are moderate to steeply dipping, calciteinfilling.[Vassalboro Formation].Rock Mass Quality = Good.R1:Core Times (min:sec)30.4-31.4 ft (3:00)31.4-32.4 ft (3:00)32.4-33.4 ft (2:30)33.4-34.4 ft (2:00)34.4-35.4 ft (2:05) 100% Recovery

R2:Similar to R1. except frequent quartz and calcite veins.Rock Mass Quality = Fair.R2:Core Times (min:sec)35.4-36.4 ft (2:00)36.4-37.4 ft (3:05)37.4-38.4 ft (3:35)38.4-39.4 ft (5:00)39.4-40.4 ft (4:30) 95% Recovery

40.40Bottom of Exploration at 40.40 feet below ground surface.

G#261753A-2-4, SMWC=9.5%










Remarks:

Auto Hammer #20



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AASHTO and

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Page 2 of 2

0

5

10

15

20

25

SSA130.03

126.70

2" PAVEMENT.0.17

Cobbles and Boulder.


Moved to BB-ADS-102


Boring No.: BB-ADS-102ASoil/Rock Exploration Log


Driller: Maine Test Boring, Inc. Elevation (ft.) 130.2 Auger ID/OD: 5" Dia.

Operator: Potter/Francis Datum: NAVD88 Sampler: N/A

Logged By: B. Wilder Rig Type: Mobile B53 Track Hammer Wt./Fall: N/A

Date Start/Finish: 8/16/11; 07:00-7:15 Drilling Method: Solid Stem Auger Core Barrel: N/A

Boring Location: 7+73.9, 1.8 ft Rt. Casing ID/OD: N/A Water Level*: None Observed


Remarks:


* Water level readings have been made at times and under conditions stated. Groundwater fluctuations may occur due to conditions otherthan those present at the time measurements were made. Boring No.: BB-ADS-102A

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AASHTO and

Unified Class.

Page 1 of 1

0

5

10

15

20

25

1D

2D

3D

4D

5D

R1

24/6

9.6/6

24/14

3.6/3

21.6/18

60/46

1.00 - 3.00

5.00 - 5.80

11.00 - 13.00

15.00 - 15.30

20.00 - 21.80

22.00 - 27.00

3/9/3/11

44/50(3.6")

13/12/22/22

50(3.6")

33/39/43/50

RQD = 30%

12

---

34

---

82

16

44

107

SSA

SPUNAHEAD

NQ-2

130.38

120.00

115.50

108.70108.50

106.50

1½" PAVEMENT.0.13

Brown, damp, medium dense, Gravelly SAND, little silt, (Fill).

Brown, wet, GRAVEL, little fine to coarse sand, little silt, (Fill)Roller Coned ahead to 10.0 ft bgs.

Loose layer from 8.4-9.6 ft bgs.

Cobble from 9.6-10.2 ft bgs.

Wood layer from 10.2-10.5 ft bgs.10.50

Grey, wet, hard, SILT, some gravel, some fine to coarse sand, (GlacialTill).

15.00Grey, wet, very dense, Silty, fine to medium SAND, little gravel,(Glacial Till).

Grey, wet, very dense, SAND, some silt, little gravel, (Glacial Till).

21.80Weathered ROCK.Roller Coned ahead to 22.0 ft bgs.

22.00R1: Weathered ROCK.R1:Core Times (min:sec)22.0-23.0 ft (6:00)

G#261754A-1-b, SMWC=4.3%

G#261755A-4, SM

WC=10.2%

G#261756A-2-4, SMWC=8.9%








Boring Location: 7+78.3, 1.5 ft Rt. Casing ID/OD: HW & NW Water Level*: 7.0 ft bgs.


Remarks:

Auto Hammer #20



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AASHTO and

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Page 1 of 2

25

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35

40

45

50

R2 52.8/52.8 27.00 - 31.40 RQD = 34%

99.10

23.0-24.0 ft (2:30)24.00

Top of Intack Bedrock at Elev. 106.5 ftR1: Bedrock: Grey to black, fine grained, finely banded SLATE, soft tomoderately hard, moderately weathered, slaty cleavage, joints in bottom2 feet are close to moderately close, open.[Vassalboro Formation].Rock Mass Quality = Poor.24.0-25.0 ft (2:45)25.0-26.0 ft (3:10)26.0-27.0 ft (3:30) 77% Recovery

R2: Bedrock: Similar to R1.Rock Mass Quality = Poor.R2:Core Times (min:sec)27.0-28.0 ft (2:25)28.0-29.0 ft (2:45)29.0-30.0 ft (2:35)30.0-31.0 ft (2:40)31.0-31.4 ft (3:00) 100% Recovery









Boring Location: 7+78.3, 1.5 ft Rt. Casing ID/OD: HW & NW Water Level*: 7.0 ft bgs.


Remarks:

Auto Hammer #20



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AASHTO and

Unified Class.

Page 2 of 2

0

5

10

15

20

25

R1

R2

R3

1D

2D

R4

60/60

48/48

48/46

24/19

8.4/6

49.2/49.2

0.00 - 5.00

5.00 - 9.00

9.00 - 13.00

13.00 - 15.00

18.00 - 18.70

22.00 - 26.10

24/15/15/13

45/50(2.4")

RQD = 0%

30

---

39

SPUNWIRE

LINE

117.60

112.40

108.40

107.20

R1: CONCRETE, drill thru Pier.100% Recovery

R2: CONCRETE and GRANITE.100% Recovery

R3: CONCRETE and GRANITE.

12.80R3: Cont: bottom of pier at 12.8 ft bgs.Grey, wet, hard, SILT, some fine to coarse sand, trace gravel, (GlacialTill).

18.00Grey, wet, very dense, silty GRAVEL, some fine to coarse SAND, somesilt, (Glacial Till).

22.00R4:COBBLES from 22.0-23.2R4:Core Times (min:sec)22.0-23.0 ft (4:00)

23.20Top of Bedrock at Elev. 107.2 ft.R4:Cont:Bedrock: Black and gray, fine grained, finely banded SLATE,

G#261757A-4, ML

WC=10.8%

G#261758A-2-4, SMWC=6.8%







Date Start/Finish: 8/16/11-8/17/11 Drilling Method: Cased Wash Boring Core Barrel: HQ-2" Wire Line



Remarks:

Auto Hammer #20Filled boring with first 2 bags of gravel, then 1 bag of Bentonite Chips and lastly with 1 bag of Rapid Set Concrete.



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AASHTO and

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Page 1 of 2

25

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35

40

45

50

R5 60/60 26.10 - 31.10 RQD = 18%

99.30

soft to moderately hard, slaty partings are moderate to steeply dipping,very close to close, tight to open, calcite and silt infilling.[Vassalboro Formation].Rock Mass Quality = Very Poor.23.0-24.0 ft (3:30)24.0-25.0 ft (2:15)25.0-26.0 ft (5:00)26.0-26.1 ft (3:00) 100% RecoveryCore Blocked

R5:Bedrock: Similar to above.Rock Mass Quality = Very Poor.R5:Core Times (min:sec)26.1-27.1 ft (4:30)27.1-28.1 ft (4:10)28.1-29.1 ft (3:30)29.1-30.1 ft (3:20)30.1-31.1 ft (3:45) 100% Recovery








Date Start/Finish: 8/16/11-8/17/11 Drilling Method: Cased Wash Boring Core Barrel: HQ-2" Wire Line



Remarks:

Auto Hammer #20Filled boring with first 2 bags of gravel, then 1 bag of Bentonite Chips and lastly with 1 bag of Rapid Set Concrete.



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AASHTO and

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Page 2 of 2

Appendix B

Laboratory Test Results

Station Offset Depth Reference G.S.D.C. W.C. L.L. P.I.

(Feet) (Feet) (Feet) Number Sheet % Unified AASHTO Frost

6+90.2 0.4 Lt. 0.5-2.5 261751 1 2.5 SW-SM A-1-a 06+90.2 0.4 Lt. 10.0-12.0 261752 1 10.6 ML A-4 IV6+90.2 0.4 Lt. 25.0-25.9 261753 1 9.5 SM A-2-4 II7+78.3 1.5 Rt. 1.0-3.0 261754 2 4.3 SM A-1-b II7+78.3 1.5 Rt. 11.0-13.0 261755 2 10.2 SM A-4 III7+78.3 1.5 Rt. 20.0-21.8 261756 2 8.9 SM A-2-4 II7+22.3 0.5 Lt. 13.0-15.0 261757 3 10.8 ML A-4 IV7+22.3 0.5 Lt. 18.0-18.7 261758 3 6.8 SM A-2-4 II

Classification of these soil samples is in accordance with AASHTO Classification System M-145-40. This classification

is followed by the "Frost Susceptibility Rating" from zero (non-frost susceptible) to Class IV (highly frost susceptible).

The "Frost Susceptibility Rating" is based upon the MaineDOT and Corps of Engineers Classification Systems.

GSDC = Grain Size Distribution Curve as determined by AASHTO T 88-93 (1996) and/or ASTM D 422-63 (Reapproved 1998)

WC = water content as determined by AASHTO T 265-93 and/or ASTM D 2216-98

LL = Liquid limit as determined by AASHTO T 89-96 and/or ASTM D 4318-98

PI = Plasticity Index as determined by AASHTO 90-96 and/or ASTM D4318-98

State of Maine - Department of TransportationLaboratory Testing Summary Sheet

Town(s): AltonBoring & Sample

BB-ADS-101, 6D

BB-ADS-102, 5D

Identification Number

BB-ADS-101, 1D

Work Number: 17866.00

BB-ADS-101, 3D

BB-ADS-103, 2DBB-ADS-103, 1D

Classification

BB-ADS-102, 1DBB-ADS-102, 3D

Borings are in Boring Number order not Station order.

1 of 1

3" 2" 1-1/2" 1" 3/4" 1/2" 3/8" 1/4" #4 #8 #10 #16 #20 #40 #60 #100 #200 0.05 0.03 0.010 0.005 0.001

76.2 50.8 38.1 25.4 19.05 12.7 9.53 6.35 4.75 2.36 2.00 1.18 0.85 0.426 0.25 0.15 0.075 0.05 0.03 0.005

GRAVEL SAND SILT

SIEVE ANALYSISUS Standard Sieve Numbers

HYDROMETER ANALYSISGrain Diameter, mm

State of Maine Department of TransportationGRAIN SIZE DISTRIBUTION CURVE

100 10 1 0.1 0.01 0.001Grain Diameter, mm

0

10

20

30

40

50

60

70

80

90

100

Per

cen

t Fi

ner

by W

eigh

t

100

90

80

70

60

50

40

30

20

10

0

Per

cen

t Ret

aine

d b

y W

eigh

t

CLAY

SHEET NO.

UNIFIED CLASSIFICATION

Gravelly SAND, little silt.

SAND, some silt, little gravel.

SILT, some sand, little gravel.

2.5

10.6

9.5

BB-ADS-101/1D

BB-ADS-101/3D

BB-ADS-101/6D

0.5-2.5

10.0-12.0

25.0-25.9

Depth, ftBoring/Sample No. Description W, % LL PL PI

��

��

��

��

��

SHEET 1

Alton

017866.00

WHITE, TERRY A 9/21/2011

WIN

Town

Reported by/Date

0.4 LT

0.4 LT

0.4 LT

Offset, ft6+90.2

6+90.2

6+90.2

Station

3" 2" 1-1/2" 1" 3/4" 1/2" 3/8" 1/4" #4 #8 #10 #16 #20 #40 #60 #100 #200 0.05 0.03 0.010 0.005 0.001

76.2 50.8 38.1 25.4 19.05 12.7 9.53 6.35 4.75 2.36 2.00 1.18 0.85 0.426 0.25 0.15 0.075 0.05 0.03 0.005

GRAVEL SAND SILT





0

10

20

30

40

50

60

70

80

90

100

Per

cen

t Fi

ner

by W

eigh

t

100

90

80

70

60

50

40

30

20

10

0

Per

cen

t Ret

aine

d b

y W

eigh

t

CLAY

SHEET NO.


Gravelly SAND, little silt.

SAND, some silt, little gravel.

SILT, some gravel, some sand.

4.3

10.2

8.9

BB-ADS-102/1D

BB-ADS-102/3D

BB-ADS-102/5D

1.0-3.0

11.0-13.0

20.0-21.8


��

��

��

��

��

SHEET 2

Alton

017866.00


WIN

Town

Reported by/Date

1.5 RT

1.5 RT

1.5 RT

Offset, ft7+78.3

7+78.3

7+78.3

Station

3" 2" 1-1/2" 1" 3/4" 1/2" 3/8" 1/4" #4 #8 #10 #16 #20 #40 #60 #100 #200 0.05 0.03 0.010 0.005 0.001

76.2 50.8 38.1 25.4 19.05 12.7 9.53 6.35 4.75 2.36 2.00 1.18 0.85 0.426 0.25 0.15 0.075 0.05 0.03 0.005

GRAVEL SAND SILT





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by W

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Per

cen

t Ret

aine

d b

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CLAY

SHEET NO.


SILT, some sand, trace gravel.

GRAVEL, some sand, some silt.

10.8

6.8

BB-ADS-103/1D

BB-ADS-103/2D

13.0-15.0

18.0-18.7


��

��

��

��

��

SHEET 3

Alton

017866.00


WIN

Town

Reported by/Date

0.5 LT

0.5 LT

Offset, ft7+22.3

7+22.3

Station

Appendix C

Calculations

Bearing Resistance

Alton, Tannery BridgeWIN 17866.00

Bearing Resistance By: B. SlavenDate: 3.22.16

Check by: LK 7.11.2016

Bearing Resistance Existing AbutmentsSpread footing on Glacial Till

Service Limit StatePresumptive Bearing Resistance for Service Limit StateReference: LRFD Table C10.6.2.6.1-1, Presumptive Bearing Resistance for Spread Footings at the Service Limit State,Based on NavFac DM 7.2, May 1983, Foundations and Earth Structures, Table 1, 7.2-142, "Presumptive Values ofAllowable Bearing Pressures for Spread Foundations."

Samples of the Glacial Till are hard, silt, some sand, some to trace gravel. (ML or SM)

Bearing Material Consistency in Place Bearing Pressure Recommended Resistance Range Value

Fine sand, silty or Very dense 6-10 ksf 6 ksfclayey med. to finesand (SP, SM, SC)

Inorganic silt, sandy Very stiff 4-8 ksf 6 ksfor clayey silt, to hard(ML, MH)

Recommend 6 ksf to limit settlement to 1.0 inch for Service Limit State Loads

Strength and Extreme Limit StatesNominal and factored bearing resistance for Strength and Extreme Limit StatesReference: Foundation Engineering and Design, 5th Ed. Bowles (1996).

Soil Mechanics, 1st Ed. Lambe & Whitman (1969).Foundation Engineering, 2nd Ed. Peck, Hanson, & Thornburn (1974).

Properties and Conditions at Bearing Elevation:

ϕ 26 deg Bowles p. 108

c 500 psf Lambe p. 310, 379

γsat 130 pcf

γdry 125 pcf

γw 62.4 pcf γeff γsat γw

Foundation Width

B 6.75 ft 1928 Historical Plans

Footing Embedment

Df 0 ft Site Observation-Existing condition




Strip footing, B L Shape Factors

sc 1.0 sγ 1.0 Bowles p. 220

Meyerhof's Bearing Capacity Shape FactorsUndrained Silt, ϕ=26 degrees

Nc 22.25 Nq 11.8 Nγ 8.0 Bowles p. 223

Effective Overburden pressure

q Df γsat γw q 0 ksf

Nominal Bearing Resistance (Terzaghi) for Strength and Extreme Limit States

qn c Nc sc q Nq 0.5γeff B Nγ sγ qn 13 ksf Bowles p. 220

Factored Bearing Resistance -- Strength Limit State

φb 0.45 AASHTO LRFD Table 10.5.5.2.2-1

qr φb qn qr 5.8 ksf

Recommendation: 5.8 ksf is to be used for Strength Limit State design for the 1928 constructionconsisting of a 6-foot 9-inch wide footing with no embedment below the streambed.

Factored Bearing Resistance -- Extreme Limit State

φb 1.0 AASHTO LRFD Article C11.5.8

qr φb qn qr 13 ksf

Recommendation: 13 ksf is to be used for Extreme Limit State design for the 1928 constructionconsisting of a 6-foot 9-inch wide footing with no embedment below the streambed.

Bearing resistance at the Strength and Extreme Limit States may be increased by embeddingexisting footings as part of abutment rehabilitation. Care must be taken to insure embedmentmaterial is not lost to scour or erosion over the rehabilitation's design life. Riprap shall not contributeto embedment depths.

Footing Embedment

Condition created by rehabilitation.All matrices are in this order.Df

1

2

3

ft

Effective Overburden pressure

q Df γsat γw q

0.068

0.135

0.203

ksf




Nominal Bearing Resistance (Terzaghi) for Strength and Extreme LimitStates for rehabilitation

qn c Nc sc q Nq 0.5γeff B Nγ sγ qn

13.7

14.5

15.3

ksf Bowles p. 220

Factored Bearing Resistance -- Strength Limit State -- Embedded

φb 0.45 AASHTO LRFD Table 10.5.5.2.2-1

qr φb qn qr

6.2

6.5

6.9

ksf for embedment depth of Df

1

2

3

ft

Factored Bearing Resistance -- Extreme Limit State -- Embedded

φb 1.0 AASHTO LRFD Article C11.5.8

qr φb qn qr

13.7

14.5

15.3

ksf for embedment depth of Df

1

2

3

ft

Earth Pressure


Calculation of Earth Pressure B. Slaven3.22.16

Checked by: LK_7.11.16

Earth Pressure Soil Parameters:Assume existing material removed and replaced with material with properties similar to Soil Type 4, MaineDOT BDG Section 3.6.1.

Unit weight γ 125 pcf

Internal friction angle ϕ 32 deg

Cohesion c 0 psf

Coulomb Theory

Coulomb theory applies for gravity, semigravity, and prefab modular walls walls with steep backfaces.Coulomb theory also applies to concrete cantilever walls with short heels where the slidingsurface is restricted by the top of wall - the wedge of soil does not move.Interface friction is considered in Coulomb.

Sheet Pile Backwall - Active Earth Pressure Coefficient

Angle of back face of wall to the horizontal, θ :

θ 90 deg

Angle of fill slope to the horizontal

β 0 deg

Friction angle between fill and wall:

δ 17 deg LRFD Table 3.11.5.3-1 for Steel onclean sand.

Check angle is between recommended ϕ

3 and

2ϕ

3 for Coulomb:

ϕ

310.7 deg

2ϕ

321.3 deg O.K.

Kacsin θ ϕ( )

2

sin θ( )2

sin θ δ( ) 1sin ϕ δ( ) sin ϕ β( )

sin θ δ( ) sin θ β( )

2

Kac 0.28




Concrete Abutment - Active Earth Pressure Coefficient

Angle of back face of wall to the horizontal, θ :

θ 90 deg

Angle of fill slope to the horizontal

β 0 deg

Friction angle between fill and wall:

δ = 24 to 29 LRFD Table 3.11.5.3-1 for Concrete onclean fine to medium sand.

Check angle is between recommended ϕ

3 and

2ϕ

3 for Coulomb:

ϕ

310.7 deg

2ϕ

321.3 deg

No Good: Use upper bound

δ 21.3deg

Kacsin θ ϕ( )

2

sin θ( )2

sin θ δ( ) 1sin ϕ δ( ) sin ϕ β( )

sin θ δ( ) sin θ β( )

2

Kac 0.28

Orientation of Coulomb Pa

In the case of gravity shaped walls, Pa is oriented degrees up from a perpendicular line tothe backface or 'pressure surface.'

Recommend: Coulomb Active Earth Pressure Coefficient, Kac= 0.28

Concrete Abutment - At-Rest Earth Pressure Coefficient

For walls less than 5 feet or braced stem walls that prevent rotation.

Ko 1 sin ϕ( )

Ko 0.47

Recommend: At-Rest Earth Pressure Coefficient, Ko= 0.47




Deadman - Passive Earth Pressure Coefficient

Bowles does not recommend use of Rankine method for Kp when β>0. Use of a ϕ angle greaterthan 35 deg will result in unconservative design.

= Angle of fill slope to the horizontalβ 0 deg

Kprcos β( ) cos β( )

2cos ϕ( )

2

cos β( ) cos β( )2

cos ϕ( )2

Kpr 3.25

Pp is oriented at an angle of to the vertical plane

Recommend: Rankine Passive Earth Pressure Coefficient, Kpr= 3.26

Deadman - Active Earth Pressure Coefficient

If δ is taken as 0 and the slope of the backslope is horizontal, there is no difference in the activeearth pressure coefficient when using either Rankine or Coulomb.

Kar tan 45 degϕ

2

2

Kar 0.31

For a sloped backfill

= Angle of fill slope to the horizontal β 0 deg

Kar_slopecos β( ) cos β( )

2cos ϕ( )

2

cos β( ) cos β( )2

cos ϕ( )2

Kar_slope 0.31

Pa is oriented at an angle of to the vertical plane

Recommend: Rankine Active Earth Pressure Coefficient, Kar= 0.31

Global Stability Evaluations

3 Analyses

12

3

4

5

1 2

3

456

7

8

91011

12

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14 15

1617

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21

22

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2425

262728

29 30

31

1.505

Name: Concrete Abutment Mass Unit Weight: 150 pcfCohesion: 10000 psfPhi: 9 °

Name: BedrockModel: Bedrock (Impenetrable)Piezometric Line: 1

Title: Global stability of Abutment 2 - longitudinal direction; along CL of Roadway into streambedComments: noneDate: 7/18/2016File Name: Alton Abutment 2 HMA Deck.gsz

Description: Global stablity of Abut 2 for proposed condition at Service I with HMA deck.

Date: 7/18/2016

Name: Embankment fill Unit Weight: 125 pcfCohesion: 0 psfPhi: 34 °

Name: Grey, moist, hard, SILT, some gravel, some sand layers. Unit Weight: 125 pcfCohesion: 500 psfPhi: 26 °Phi-B: 0 °

Surcharge (Heq=2.65 ft): 331 pcf Value: 9130 lbs*

Name: Embankment fill Unit Weight: 125 pcf Cohesion: 0 psf Phi: 34 ° Name: Grey, wet, dense, silty SAND, sand or silty gravel (Glacial Till) Unit Weight: 125 pcf Cohesion: 0 psf Phi: 35 ° Name: Bedrock Name: Grey, moist, hard, SILT, some gravel, some sand layers. Unit Weight: 125 pcf Cohesion: 500 psf Phi: 26 ° Name: Concrete Abutment Mass Unit Weight: 150 pcf Cohesion: 10000 psf Phi: 9 °

*Provided by MaineDOT Structural Engineer

Name: Grey, wet, dense, silty SAND, sand or silty gravel (Glacial Till) Unit Weight: 125 pcfCohesion: 0 psfPhi: 35 °

Distance (feet)

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Ele

vatio

n (f

eet)

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456

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91011

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1617

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22

23

2425

262728

29 30

31

1.464



Title: Global stability of Abutment 2 - longitudinal direction; along CL of Roadway into streambedComments: noneDate: 7/18/2016File Name: Alton Abutment 2 Conc Deck.gsz

Description: Global stablity of Abut 2 for proposed condition at Service I with concrete deck.

Date: 7/18/2016



Surcharge (Heq=2.65 ft): 331 pcf Value: 11540 lbs*




Distance (feet)

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Ele

vatio

n (f

eet)

0

10

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30

40

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60

70

12

3

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1 2

3

456

7

8

91011

12

13

14 15

1617

18 19

20

21

22

23

2425

262728

29 30

31

32

1.807



Title: Global stability of Abutment 2 - longitudinal direction; along CL of Roadway into streambedComments: noneDate: 7/18/2016File Name: Alton Abutment 2 Conc Deck with Anchor.gsz

Description: Global stablity of Abut 2 for proposed condition with deadman at Service I with concrete deck.

Date: 7/18/2016



Surcharge (Heq=2.65 ft): 331 pcfValue: 11540 lbs*




Type: AnchorTotal Length: 26 ftBar Load: 5600 lbs

Distance (feet)

0 10 20 30 40 50 60 70 80 90 100 110 120 130

Ele

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n (f

eet)

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Frost Depth

Alton17866

Frost Penetration Analysis B.SlavenMar 2015

Check by : LK 7/2016

Method 1 - MaineDOT Design Freezing Index (DFI) Map and Depth of Frost Penetration Table, BDGSection 5.2.1.

From Design Freezing Index Map: Alton, MaineDFI = 1850 degree-days. Case 1 - coarse grained granular fill soils W=10% (assumed).

For DFI = 1700 d1 90.1

For DFI = 1900 d2 92.6

d ind2 d1

102 d1

Depth of Frost Penetration d 91 in d 7.6 ft

Method 2 - ModBerg Software

Examine foundations placed on coarse grained fill soils

Orono lies along the same Maine Design Freezing Index contour - use Orono data from Modberg's freezing indexdatabase.

--- ModBerg Results ---

Project Location: Waterville, Maine Air Design Freezing Index = 1588 F-days N-Factor = 0.80 Surface Design Freezing Index = 1270 F-days Mean Annual Temperature = 43.5 deg F Design Length of Freezing Season = 132 days --------------------------------------------------------------------------------------------------------------- Layer #:Type t w% d Cf Cu Kf Ku L --------------------------------------------------------------------------------------------------------------- 1-Coarse 88.4 10.0 135.0 30 36 2.9 2.1 1,944 --------------------------------------------------------------------------------------------------------------- t = Layer thickness, in inches. w% = Moisture content, in percentage of dry density. d = Dry density, in lbs/cubic ft. Cf = Heat Capacity of frozen phase, in BTU/(cubic ft degree F). Cu = Heat Capacity of thawed phase, in BTU/(cubic ft degree F). Kf = Thermal conductivity in frozen phase, in BTU/(ft hr degree). Ku = Thermal conductivity in thawed phase, in BTU/(ft hr degree). L = Latent heat of fusion, in BTU / cubic f Total Depth of Frost Penetration = 7.36 ft = 88.4 in.

Recommendation: 7.5 feet for design of foundations constructed on coarse grained soils

1 of 1

Seismic Parameters

Alton Tannery Br17866

Siesmic Site Classification B. SlavenMar 2016

Check by: LK 7/2016

BB-101 BB-102 BB-103

Depth SPT N di di/N Depth SPT N di di/N Depth SPT N di di/N2 48 2 0.04 2 16 2 0.135 10 3 0.30 5 50 3 0.0610 50 5 0.10 10 44 5 0.1115 42 5 0.12 15 50 5 0.1020 37 5 0.14 20 100 5 0.0525 50 5 0.10 20 100 Bedrock 80 0.8030 75 5 0.0730 100 Bedrock 70 0.70

SUM 100 1.56 100 1.25

di/di/N 64.00 di/di/N 80.09

SUM Nav. 72.04

Sample too small for inclusion

Conclusion: Site Class C

Site Classification per LRFD Table C3.10.3.1-1 - Method B

Alton Tannery Br Seismic Parameters B. Slaven 17866 Mar 2016 Check by: LK 7/2016

Conterminous 48 States 2007 AASHTO Bridge Design Guidelines

Spectral Response Accelerations SDs and SD1 Latitude = 45.000000 Longitude = -068.800000

As = FpgaPGA, SDs = FaSs, and SD1 = FvS1 Site Class C - Fpga = 1.20, Fa = 1.20, Fv = 1.70

Data are based on a 0.05 deg grid spacing. Period Sa (sec) (g)

0.0 0.084 As - Site Class C 0.2 0.181 SDs - Site Class C 1.0 0.077 SD1 - Site Class C

Conterminous 48 States 2007 AASHTO Bridge Design Guidelines Design Response Spectra for Site Class C Latitude = 45.000000 Longitude = -068.800000 As = FpgaPGA, SDs = FaSs, SD1 = FvS1 Site Class C - Fpga = 1.20, Fa = 1.20, Fv = 1.70 Data are based on a 0.05 deg grid spacing. Period Sa Sd (sec) (g) in. 0.000 0.084 0.000 T = 0.0, Sa = As 0.085 0.181 0.013 0.200 0.181 0.071 T = 0.2, Sa = SDs 0.424 0.181 0.318 T = Ts, Sa = SDs 0.500 0.154 0.375 0.600 0.128 0.450 0.800 0.096 0.601 1.000 0.077 0.751 T = 1.0, Sa = SD1 1.200 0.064 0.901 1.400 0.055 1.051 1.600 0.048 1.201 1.800 0.043 1.351 2.000 0.038 1.502 2.200 0.035 1.652 2.400 0.032 1.802 2.600 0.030 1.952 2.800 0.027 2.102 3.000 0.026 2.252 3.200 0.024 2.403 3.400 0.023 2.553 3.600 0.021 2.703 3.800 0.020 2.853 4.000 0.019 3.003

Alton Tannery Br Seismic Parameters B. Slaven 17866 Mar 2016 Check by: LK 7/2016

17866 Alton Tannery Bridge Geotechnical Report Rev1 ...

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