SUBSURFACE EXPLORATION AND PAVEMENT DESIGN REPORT

Transcription

1 GEOSCIENCES & ENGINEERING 7290 South Fraser Street Centennial, Colorado Phone: SUBSURFACE EXPLORATION AND PAVEMENT DESIGN REPORT TOWER ROAD AT PENA BOULEVARD IMPROVEMENTS CITY AND COUNTY OF DENVER, COLORADO Prepared For Mr. Len Wilson, P.E. CORE Consultants 1950 W. Littleton Boulevard, Suite 109 Littleton, Colorado August 4, 2017 revised September 6, 2017

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3 TABLE OF CONTENTS Page 1.0 PURPOSE AND SCOPE PROPOSED CONSTRUCTION SITE CONDITIONS SUBSURFACE EXPLORATION SUBSURFACE CONDITIONS LABORATORY TESTING FOUNDATION RECOMMENDATIONS DRIVEN H-PILES DRILLED SHAFT FOUNDATIONS DRILLED SHAFT FOUNDATIONS SIGNAL POLES LATERAL CAPACITY PARAMETERS RETAINING STRUCTURES UNDERDRAIN SYSTEM SITE GRADING AND SETTLEMENT PAVEMENT DESIGN TOWER ROAD MGPEC PAVEMENT DESIGN PENA BOULEVARD RAMPS CDOT PAVEMENT DESIGN PAVEMENT MATERIALS AND SUBGRADE RECOMMENDATIONS LIMITATIONS Figures 1-A and 1-B Figures 2-A and 2-B Figure 3 Figures 4 through 8 Figures 9a through 9c Figures 10 through 14 Figures 15 through 17 Figures 18 and 19 Figure 20 Table 1 Table 2 Appendix A Appendix B FIGURES, TABLES, AND APPENDICES Locations of Exploratory Borings Logs of Exploratory Borings Legend and Notes for Exploratory Borings Swell-Compression Test Results Consolidation Test Results Gradation Test Results Moisture-Density Relationship Test Results Unconfined Compression Test Report Bearing Ratio Test Report Summary of Laboratory Test Results Summary of Laboratory Chemical Test Results MGPEC Pavement Design Software Printouts MGPEC Form #9 AASHTO Design Software Printouts Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page ii

4 1.0 PURPOSE AND SCOPE This report contains the results of a subsurface exploration and pavement design conducted for the proposed roadway improvements at the Tower Road and Pena Boulevard interchange in the City and County of Denver, Colorado. A subsurface exploration was conducted to obtain information on soil, bedrock, and groundwater conditions. Soil and bedrock samples were visually classified, and selected samples were laboratory tested to evaluate strength, compressibility or swell characteristics, classification, and other related engineering properties. The results of the field and laboratory testing programs were evaluated to develop geotechnical recommendations for the proposed pavement sections as well as foundation recommendations for the West Fork Second Creek Crossing structure and for signal pole foundations. We understand that auxiliary equipment for the traffic poles, such as controller and power cabinets, will not require engineered foundations although light poles with banners will. The subsurface exploration, traffic loading, and design pavement section calculations for Tower Road are based on the 2001 Metropolitan Government Pavement Engineers Council (MGPEC) procedures; traffic loading and design pavement section calculations for the Pena Boulevard ramps are based on the Colorado Department of Transportation (CDOT) design procedures. This report has been prepared to summarize the data obtained and to present our conclusions and recommendations based on the proposed construction and the subsurface conditions encountered. Design parameters and a discussion of geotechnical engineering conditions related to construction of the proposed project are included. Environmental considerations related to the occurrence or potential occurrence of hazardous materials are beyond the scope of this study. Our services were provided in general accordance with our agreement with CORE Consulting, Inc., dated June 16, PROPOSED CONSTRUCTION Based on the available information provided by CORE, we understand that the proposed construction will consist of new exit and entrance ramps for westbound Pena Boulevard at Tower Road. The existing westbound Pena Boulevard bridge over the West Fork Second Creek is expected to be widened to accommodate the new entry Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 1 of 25

5 ramp. The westbound Pena Boulevard off-ramp and intersection with Tower Road will be relocated approximately 550 feet to the south of the current alignment, in a tight diamond configuration to the north of Pena Boulevard. New traffic signals are planned for the westbound Pena Boulevard ramps and the existing signal poles for the eastbound Pena Boulevard ramps will be evaluated to determine if replacement is needed. The Tower Road intersection with the eastbound Pena Boulevard ramps is expected to be reconstructed, and the eastbound Pena Boulevard off ramp will be widened to accommodate a new right turn lane. The improvements for Tower Road are expected to include roadway widening to accommodate two travel lanes in each direction with a raised, landscaped center median. Auxiliary acceleration, deceleration, and turn lanes may be included at intersections as needed. The new median centerline will generally follow the centerline of existing Tower Road. Portions of the existing asphalt pavement will be completely removed to accommodate the new roadway, and a functional overlay (i.e. mill and fill) is also planned for a portion of Tower Road in the area of the Pena Boulevard interchange. Other improvements will include on-street bike lanes, detached concrete paved sidewalk and bike path, and room for a third travel lane in each direction for future expansion. Cut and fill depths for Tower Road are expected to be minor, however cut and fill depths for the new ramps could be up to 15 feet high. 3.0 SITE CONDITIONS The project corridor is situated within the Colorado Piedmont in an area of low rolling uplands northeast of Denver, Colorado. This area is characterized by subdued topography that has been graded for roadway and commercial development. Land use in the surrounding area is generally agricultural with some undeveloped land along the West Fork Second Creek that crosses the project area. Non-agricultural commercial development in the surrounding area includes a dedicated airport parking area east of the intersection of Tower Road with 81st Avenue, the Allied Waste Tower Landfill located near the 8400 block of Tower Road, and several hotels and restaurants located along Tower Road between East 71 st and 67 th Avenues. The recently completed Denver RTD A Line roughly parallels Pena Boulevard about 1 / 3 to ½ miles to the south of the project corridor, and the eastern boundary of the Rocky Mountain Arsenal is located about ½ miles to the west of the west end of the project area. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 2 of 25

6 Drainage in the project corridor is to the north, along the West Fork Second Creek that flows from the southeast and crosses Pena Boulevard about ¼ mile to the west of Tower Road. Artificial drainages along the edges of Pena Boulevard flow to the west and to the east into this tributary along the foot of the highway embankments. At the time of drilling, water was flowing in both the West Fork Second Creek and in the artificial drainage on the north side of Pena Boulevard and west of the West Fork Second Creek. Topographic relief into the West Fork Second Creek is about 60 feet from the west and about 90 feet from the east along Pena Boulevard. The embankments for Pena Boulevard are about 20 feet high in the area of Tower Road and the area of the West Fork Second Creek. Published geological mapping assigns natural unconsolidated surficial soils in the project area to deposits of Holocene and Pleistocene age loess and deposits of Holocene Piney Creek Alluvium along Second Creek and its tributaries. The loess is described as sandy silt with appreciable amounts of clay and silty clay and the Piney Creek Alluvium as interbedded deposits of sand silt and clay. Bedrock is assigned to the Denver Formation, consisting of claystone and fine-grained sandstone. Published mapping indicates bedrock is shallow and may be locally exposed along Second Creek and along the eastern side of the West Fork Second Creek that crosses the project corridor. Soils in these areas are identified as having high swell potential and may require special foundation design and landscaping to prevent damage. Based on published geohydrologic maps, groundwater is indicated to be in the range of 10 feet to 20 feet deep and is interpreted as flowing from southeast to northwest in unconfined alluvial aquifers. 4.0 SUBSURFACE EXPLORATION The subsurface exploration for this project was conducted on August 11, 2016 and consisted of drilling twelve borings along Pena Boulevard and Tower Road, at the approximate locations shown on Figures 1-A and 1-B, Locations of Exploratory Borings. These borings, which consisted of Borings P-7 through P-15, B-1, B-2, and I-1 were drilled to supplement the data collected from the exploratory borings drilled on November, 2014, within the City and County of Denver portion of the Tower Road Widening project. The results of the borings drilled during the 2014 subsurface exploration (Borings P-1 through P-6), were submitted in our draft report entitled Draft Subsurface Exploration and Pavement Design Report, Tower Road Widening, 104 th Avenue to Pena Boulevard, Commerce City and Denver, Colorado. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 3 of 25

7 The borings were drilled with a CME 55 truck-mounted drill-rig equipped with 4 inch diameter solid stem augers. Prior to drilling Boring P-13, the existing concrete pavement on the westbound Pena Boulevard off-ramp was cored using a 4½ inch diameter core barrel. A representative of Geocal, Inc. logged the borings and collected the pavement core. Soil and bedrock samples were collected generally following the ASTM D 3550 test standards, and using a nominal 2 inch ID California spoon sampler. The penetration resistance values, when properly evaluated, indicate the relative consistency or density of the soils or bedrock hardness. Samples were obtained at approximate 5 foot intervals, and composite bulk samples of auger cuttings were obtained from the upper five feet of the borings. Samples collected during drilling were transported to our laboratory for review by our project engineer and selected samples were programmed for laboratory testing. After drilling, the borings were backfilled with compacted auger cuttings and make-up sand and gravel. Borings B-1 and B-2 were left open overnight for follow-up groundwater level readings and were backfilled the day after drilling. Boring P-13 was capped with 9 inches of Transpatch quick setting concrete blended with pea gravel, and the borings drilled along Tower Road which penetrated asphalt pavement were capped with asphalt patching material compacted in lifts to a total thickness of 9 inches, or the thickness of the existing pavement, whichever was greater. Logs of the subsurface conditions encountered, including depths at which samples were collected, penetration resistance values, and groundwater information are shown on Figures 2-A and 2-B, Logs of Exploratory Borings. Descriptions of the materials encountered and notes regarding the symbols used are presented on Figure 3, Legend and Notes for Exploratory Borings. 5.0 SUBSURFACE CONDITIONS The following paragraphs provide a generalized description of subsurface conditions encountered at the boring locations. For more detailed information, refer to the boring logs shown on Figures 2-A and 2-B. Tower Road: Borings P-14, P-15, and I-1 were drilled in the existing travel lanes of Tower Road. Borings P-14 and P-15 were drilled to depths of 5 feet below grade for pavement design information and Boring I-1 was Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 4 of 25

8 drilled to approximately 25 feet below grade for pavement and signal pole foundation design. Borings P-14, P-15, and I-1 encountered approximately 10 inches to 11 inches of asphalt pavement at the ground surface. Aggregate base course (ABC) was not encountered. Below the asphalt pavement the borings drilled from Tower Road encountered a layer of artificial fill approximately 1½ feet to 3 feet thick. The artificial fill generally consisted of sandy lean clay and was medium stiff to very stiff, medium to high plasticity, and contained trace fine subrounded gravel. Natural sandy lean clays were encountered below the artificial fill and extended to weathered claystone bedrock in Borings P-15 and I-1, and to the total depth explored in Boring P-14, 5 feet below grade. The natural clays were stiff, low to medium plasticity, and occasionally sandy with fine to medium sand. Weathered claystone bedrock was encountered below the natural clays in Borings P-15 and I-1 at approximately 4½ feet below existing grades. The weathered claystone was firm to medium hard, medium to high plasticity, orangish brown to bluish gray, and contained trace to common subangular fine sand. Groundwater was not encountered in the borings drilled along Tower Road at the time of drilling. Pena Boulevard Exit Ramp: Boring P-13 was drilled from the Pena Boulevard off ramp and was drilled to 5 feet below grade for pavement design information and encountered 8 inches of concrete pavement. Approximately 3 inches of chemically stabilized subgrade was immediately below the concrete pavement, which generally consisted of very hard lean clay with sand. Artificial fill consisting of stiff clay with sand was encountered below the chemically stabilized layer, which extended to the depth explored in the boring, 5 feet below grade. Boring P-12 was located north of Pena Boulevard along the alignment of the planned exit ramps and was drilled to between 10 feet below grade for pavement design information. Boring P-12 encountered approximately 2 feet of natural stiff clay with sand, overlying weathered claystone bedrock which extended to the depth explored, 10 feet below grade. Groundwater was not encountered in the borings while drilling. Pena Boulevard Entry Ramp: Borings P-7 through P-9 were drilled from the north shoulder of westbound Pena Boulevard and encountered artificial fill at the ground surface. The fill consisted of sandy lean clay with gravel and was stiff, medium plasticity, and extended to the total depth of Borings P-7 and P-8, and to weathered claystone bedrock in Boring P-9 at a depth of approximately 4 feet. The weathered claystone bedrock encountered in Boring P-9 was firm to medium hard, medium to high plasticity, and was interbedded with layers of lignite (up to 3 feet thick) and sandstone bedrock (4 feet thick) which extended from about 12 feet to 19 feet below grade. Below the lignite and sandstone interbeds, the weathered claystone bedrock extended to 25 feet below grade, the maximum depth explored in Boring P-9. Borings B-1 and B-2 were drilled from the north toe of the westbound Pena Boulevard embankment slope and were drilled to approximately 50 feet below grade for foundation design information for the planned structure Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 5 of 25

9 over the West Fork Second Creek. Boring B-2 encountered a layer of artificial fill approximately 2 feet thick which consisted of stiff, sandy lean clay. Natural soils were encountered below the fill in Boring B-2 and at the surface in Boring B-1, which consisted of sandy lean clay and was medium stiff to stiff, moist, and medium plasticity. The natural soils extended to weathered claystone at depths of 10 feet below grade in Boring B-1 and 17 feet below grade in Boring B-2. The weathered claystone was interbedded with layers of lignite (coal) 2 feet to 3 feet thick. Hard to very hard claystone bedrock was encountered below the weathered claystone and lignite at 26 feet below existing grades in Borings B-1 and B-2. The claystone bedrock was high plasticity, bluish green to gray, and contained occasional lignite intervals. Borings P-10 and P-11 were drilled long the alignment of the planned entry ramp to the north of Pena Boulevard and were drilled to approximately 10 feet to 15 feet below grade for pavement design information. The borings encountered natural stiff, sandy lean clay and clayey sand at the ground surface. The natural soils extended to the depth explored in Boring P-10, 10 feet below existing grade, and to weathered claystone bedrock in Boring P- 11 at a depth of 9 feet. The weathered claystone bedrock extended to the total depth explored in Boring P-11, 15 feet. Groundwater was encountered in Borings B-1 and B-2 at the time of drilling and these borings were left open overnight to obtain static groundwater level measurements; overnight ground water depths were approximately 2.9 feet below grade in Boring B-1 and 5.5 feet below grade in Boring B-2. Groundwater was also encountered in Boring P-9 at the time of drilling a depth of 14.3 feet. Boring P-9 is located on the north side of Pena Boulevard at the top of the highway embankment and is in the vicinity of Boring B-1 and the West Fork Second Creek. Groundwater levels should be expected to change with varying seasonal and climatic conditions. 6.0 LABORATORY TESTING Laboratory tests conducted on selected soil samples consisted of swell-compression, time consolidation, gradation, Atterberg limits (liquid and plastic limits), moisture-density relationship (Proctor), Resistance R-value, California Bearing Ratio (CBR), remolded unconfined compressive strength, water-soluble sulfate, water-soluble chloride, ph, and laboratory resistivity. Geocal s laboratory test results are presented on Figures 4 through 20, and are summarized in Table 1. A summary of the chemical test results is provided in Table 2. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 6 of 25

10 Swell-Compression: Swell-compression tests (ASTM D4546) were conducted on selected samples to evaluate compressibility or swell characteristics under loading and wetting. The samples were placed in odometer rings between porous discs, and an initial load ranging from 200 pounds per square foot (psf) to 1,000 psf was applied and allowed to stabilize. After stabilization, the samples were submerged and the percent volume change measured. Samples were then incrementally loaded and the volume change monitored until deformation practically ceased under each load. The swell-compression test result are shown on Figures 4 through 8 and indicate low to moderate swell potential under light surcharge loading and wetting for the clay samples tested. The claystone bedrock samples tested exhibit moderate swell potential. The results also indicate moderate compressibility for the soil tested under increased loading. Time Consolidation: These tests were done to estimate the time required for consolidation (settlement) to occur under the anticipated loading. The samples were loaded similarly to the above swell tests with loading past the estimated pre-consolidation pressure done under assumed saturated conditions. The amount of time for consolidation to occur under each loading was plotted on a log of time vs deformation and on square root of time vs deformation. From these plots, a time factor was determined and used to estimate the time required for settlement to occur, primarily at the approaches to the West Fork Second Creek crossing structure where significant fill is expected. The results of the time consolidation tests are shown on Figures 9a through 9c. Gradation and Atterberg Limits: Soil samples were classified in accordance with the American Association of State Highway and Transportation Officials (AASHTO) and Unified Soil Classification systems. The classification systems are based on the Liquid Limit (ASTM D423), Plastic Limit (ASTM D424) and grain size distribution (ASTM D422). These parameters provide qualitative information on the suitability of the soils for use in civil engineering projects. Gradation and Atterberg limits test results are shown on Figures 10 through 14. The combined gradation and Atterberg limits test results indicate that the soils tested were fine grained, medium to high plasticity, with variable amounts of sand. The AASHTO soil classifications were mostly A-6 (sandy lean clay) and A-7-6 (fat clay), with group indices ranging from 0 to 36. The Atterberg Limits tests also indicate that a majority of the clay soils tested have slight to moderate expansive potential. Moisture Density Relationship: The moisture-density relationship test is performed to evaluate the density variation that occurs with a particular soil sample with different moisture contents using the same compaction Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 7 of 25

11 effort. The test results were used to determine the remolding criteria for the remolded unconfined compression test, and California Bearing Ratio test. Figure 15 shows the results for a combined bulk sample of auger cuttings taken from the upper 5 feet of Borings P-11 and P-12. The combined bulk sample classified as lean clay with sand and had a maximum dry density of pounds per cubic foot (pcf) with an optimum moisture content of 18.6%. Figure 16 shows the results for a combined bulk sample of auger cuttings taken from the upper 5 feet of Borings P-14 and P-15. The combined bulk sample classified as sandy lean clay and had a maximum dry density of pounds per cubic foot (pcf) with an optimum moisture content of 14.3%. The results shown on Figure 17 for a bulk sample taken from the upper 5 feet of Borings P-3 indicate that the sample of lean clay with sand tested has a maximum dry density of pounds per cubic foot (pcf) with an optimum moisture content of 18.3%. Remolded Unconfined Compressive Strength: This test is a measurement of the compressive strength of a remolded soil sample under axial loading without lateral confinement. The test is useful in evaluating soil strength, for bearing capacity, global and slope stability, elastic properties such as for lateral load capacities for deep foundations, and to provide an added method of evaluating the soil resilient modulus (M r). Test results are shown on Figure 18 for a remolded bulk soil sample obtained from the upper five feet in Boring P-3. The sample was compacted to about 95% of its maximum dry density at 2% above optimum moisture content. The test results on Figure 18 show an unconfined strength of 3,388 psf. Test results are shown on Figure 19 for a combined bulk sample of auger cuttings collected from the upper 5 feet of Borings P-14 and P-15. The combined bulk sample was recompacted to about 95% of its maximum dry density at 2% above optimum moisture content, and had an unconfined strength of 4,299 psf. California Bearing Ratio (CBR) Tests: The CBR test is a penetration test where a standard square piston (2 in 2 ) penetrates the soil at a rate of 0.05 inches per minute. The CBR value is the ratio of the test load to a standard unit load and may be used to help estimate the Resilient Modulus (M r) for pavement design. The CBR value is empirically related to the required thickness of pavement structure for a given traffic loading. Results of CBR tests for the composite bulk sample tested, shown on Figure 20, indicate a value of less than 2%, at approximately 95% of the standard Proctor test value, indicating a very low subgrade pavement support value, based on the relative degree of compaction for the soil. Water-Soluble Sulfates: The water-soluble sulfate test is a measurement of the potential degree of sulfate attack on concrete exposed to the onsite soils and bedrock. Sulfate solutions react with tri-calcium aluminate hydrate, which is a normal constituent of Portland cement concrete, forming calcium sulfo-aluminate hydrate with an Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 8 of 25

12 accompanying substantial volume expansion which causes cracking. Sulfate expansion problems will typically exist when the soils have sulfate concentrations in excess of 0.10%. The concentration of water-soluble sulfates measured on the samples tested ranged from not detected to 0.82%. The test results indicate a Class 2 Severity of Sulfate Exposure in accordance with Table of the Colorado Department of Transportation (CDOT) Standard Specifications for Road and Bridge Construction (2011 Edition). For design, Class 2 requirements, as defined in Section Sulfate Resistance should be used for concrete exposed to the soils along the corridor. Water soluble sulfate test results are summarized in Table 2. Buried Metal Corrosion: Laboratory resistivity, chloride, and ph tests were conducted on a sample of clayey sand and the results are summarized in Table 2. These test results may be used to help evaluate the corrosion potential to buried metal. The test results indicate laboratory resistivity values ranging from 170 ohm-cm to 550 ohm-cm, laboratory ph values ranging from 6.8 to 8.1, and water soluble chloride contents ranging from % to %. A corrosion specialist should be consulted to interpret the results. 7.0 FOUNDATION RECOMMENDATIONS We understand that the existing Pena Boulevard bridge over the West Fork Second Creek (Structure No. D- 31-AB-60) will be widened approximately 32 feet to 37 feet towards the north, to accommodate the new westbound Pena Boulevard on ramp. Based on the available structure plans provided by Core, the existing structure is supported by driven H-pile foundations. Based on the subsurface conditions encountered in the exploratory borings, Driven H-piles or drilled shafts bearing in the underlying sedimentary bedrock may be considered for support of the proposed bridge widening. A spread footing foundation system may not be feasible for support of the new, widened bridge abutments due to the large amount of very loose/very soft soils below the expected bearing elevation and the potential for excessive settlement, even under light loads. Wingwalls should be supported by the same foundation type used to support the bridge abutments. Recommendations for driven piles and drilled shaft foundations are provided in the following sections. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 9 of 25

13 7.1 DRIVEN H-PILES Driven H-piles may be used for support of the new widened bridge structure. Recommendations presented in this section are based on the 2014 AASHTO LRFD Bridge Design Specifications, 7 th Edition, the subsurface data obtained, our experience, and local geotechnical engineering practice. Installation of driven piles should be in accordance with Section 502 Piling of the 2011 Colorado Department of Transportation Standard Specifications for Road and Bridge Construction (CDOT Standard Specifications) and applicable Special Provisions. 1) Piles should consist of heavy steel H-sections consisting of Grade A50 steel or higher, and be driven to refusal in the underlying bedrock. Refusal criteria should be determined during construction using the Pile Driving Analyzer (PDA) in accordance with Section 502 of the CDOT Standard Specifications. 2) H-piles driven to refusal in the underlying bedrock may be designed for the structural capacity of the pile section. A combined side shear and end bearing nominal capacity of 38 kips per square inch (ksi) times the cross sectional area of the pile may be used for grade A50 steel. A resistance factor of 0.65 should be applied. During construction, the wave equation analyses pile capacity should be confirmed with a PDA (Pile Driving Analyzer) on at least two piles from each abutment. 3) H-piles are expected to encounter refusal within about the upper few feet of the bedrock surface, although some variation in the bedrock surface elevation and penetration depths should be expected. If pile tip elevations are required to extend far into bedrock, the use of pile tips should be considered to reduce the risk of damaging the pile during installation. 4) Settlement of properly constructed driven piles is expected to be nominal, on the order of ½ inch or less. 5) Lateral parameters are provided in Section 7.4 Deep Foundation Lateral Capacity Parameters. Additional resistance to horizontal forces can be provided with battered piles. The vertical and horizontal components of the load will depend on the batter inclinations. Batter should not exceed 1:4 (horizontal to vertical) inclination. 6) Uplift resistance should be limited to the soil/pile interface and side shear friction above the bedrock penetration. The side shear friction value should be assumed to start at depth of 3 feet below the ground surface and increase linearly to an nominal value of 200 psf at a depth of 10 feet, then remain constant to the bedrock surface. No side shear capacity should be assumed for the top three feet of the pile to account for surface disturbance and frost action. A Resistance Factor of 0.35 should be applied to the nominal value. Pile and pile cap weights may be included in dead weight resistance to uplift forces. 7) Pile groups will require appropriate reductions of the axial capacities based on the effective envelope of the pile group. For axial and uplift, this reduction can be avoided by spacing the piles no closer than 3 diameters from center to center. Piles spaced closer than 3 diameters should be evaluated on an individual basis to establish the appropriate reduction in the design parameters. 8) Refusal criteria should be determined during construction using the Pile Driving Analyzer (PDA) in accordance with Section 502 of the CDOT Standard Specifications. PDA tests should be conducted on a minimum of two piles at each abutment. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 10 of 25

14 9) The pile driving contractor should provide the results of a GRLWeap drivability analysis for the pile driving equipment proposed for use, and the type of pile in accordance with the CDOT specifications prior to pile driving operations. 10) The pile driving operation should be observed by Geocal personnel on a full-time basis. Piles should be observed and checked for buckling, crimping and alignment in addition to recording penetration resistance and general pile driving operations. 7.2 Drilled Shaft Foundations A drilled shaft foundation supported by the underlying claystone bedrock may also be considered for support of the West Fork Second Creek bridge. Installation should be in accordance with Section 503 of the Standard Specifications for Road and Bridge Construction (2011) by the Colorado Department of Transportation (CDOT standard specifications). The design and construction criteria presented below should be observed. 1) Drilled shafts should be designed for the following nominal strength values in pounds per square foot (psf): Nominal Base Resistance (ksf) Nominal Side Shear Resistance (ksf) The above values are for that portion of the shaft in very hard sedimentary bedrock (claystone, sandstone, siltstone, etc.). The overlying soils and weathered bedrock should not be considered to provide axial capacity for drilled shafts. The weathered zone is expected to grade to competent bedrock below approximate elevation 5225 feet in the area of the West Fork Second Creek crossing. A resistance factor of 0.55 should be applied to the nominal base resistance, 0.60 should be applied for side shear, and 0.40 should be applied for side shear resistance to resist uplift. The following allowable stress design values are expected to correspond to the above values, assuming a load factor of 1.4. Maximum Allowable Allowable Side Allowable Side Shear Bearing Pressure (ksf) Shear Resistance (ksf) Resistance for Uplift (ksf) ) Drilled shafts should penetrate at least 8 feet into competent bedrock and have a minimum length of 20 feet for the capacities presented in Item 1 above to be valid. These are geotechnical parameters. Greater penetration depths may be needed based on the structural requirements. Drilled shafts should not terminate in a coal layer, and any coal layers encountered below elevation 5225 should not be counted as bedrock penetration. Any layer of coal encountered should be made up for by additional penetration into competent bedrock. 3) Settlement of properly constructed drilled shafts is expected to be on the order of ½ inch or less. 4) The minimum spacing requirements between drilled shafts should be 3 diameters from center to center. At this spacing, no reduction in the axial design parameters is required. Drilled shafts grouped less than 3 diameters center to center (B) should be studied on an individual basis to evaluate the appropriate reduction Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 11 of 25

15 in axial capacity. Article of the 2014 AASHTO LRFD Bridge Design Specifications provides efficiency factors which should be applied to the axial capacity of each individual shaft depending on the center-to-center spacing of the shafts. 5) Lateral capacity analysis parameters are presented in Section 7.4, Deep Foundation Lateral Capacity Parameters. 6) Drilled shaft holes should be properly cleaned prior to placement of reinforcing steel or concrete. A maximum length to diameter ratio of 25 is recommended to facilitate cleaning and observation of the shaft hole. 7) Concrete utilized in the drilled shafts should be a fluid mix with sufficient slump so it will fill the voids between reinforcing steel and the shaft hole. Concrete as specified by the Colorado Department of Transportation Standard Specifications for Road and Bridge Construction (CDOT Standard Specifications), for Class BZ mix is recommended. 8) The presence of groundwater in the exploratory borings and the presence of soils with potential for caving indicates that casing and/or mud slurry methods may be needed to reduce water infiltration and to stabilize the walls of drilled shaft holes from caving. If water cannot be removed, or if it is impractical to remove the water prior to placement of concrete, then concrete should be placed using an approved tremie method. Concrete placement should occur after the hole has been well cleaned. In no case should concrete be placed through more than 2 inches of water. 9) If casing is used, a sufficient head of concrete should be maintained inside the casing during removal to prevent voids being formed in the concrete. The concrete level should not be allowed to rise during casing removal. If it becomes apparent that voids may have formed during shaft installation, the contractor should be required to perform non-destructive tests to evaluate the continuity and integrity of the shafts. Tests may include sonic echo tests or other tests. 10) Bedrock penetration should be measured down from the bottom of the casing or top of hard to very hard bedrock, whichever is the lower elevation. 11) Concrete should be placed in drilled shafts the same day they are drilled. The presence of water and/or caving soils will most likely require the concrete to be placed immediately after the drilled shaft hole is completed. Failure to place concrete the day of drilling will result in bedrock degradation and a requirement for additional penetration. The amount of additional penetration will be a function of how long the hole is left open and whether or not water accumulates during the inactive period. If the drilled shaft is left open overnight, this office should be contacted for evaluation of additional penetration. 12) The drilling contractor should mobilize equipment of sufficient size and operating condition to penetrate the materials and to achieve the required penetration. 13) Care should be taken to prevent forming mushroom shapes at the top of the drilled shafts. The use of sonotube of the appropriate shaft diameter and/or mud slurry may be needed. 14) Installation of drilled shafts should be observed by a representative of Geocal, Inc. to verify bedrock, bedrock penetration, placement of reinforcing steel, clean-out of the holes prior to placement of concrete, placement of concrete, and removal of casing. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 12 of 25

16 7.3 DRILLED SHAFT FOUNDATIONS SIGNAL POLES New traffic signals are expected to be installed as part of the Tower Road improvements. Along the project corridor, the soils are expected to be lean to fat sandy clays and clayey sands within the upper 20 feet. Drilled shaft foundations for support of traffic signal poles may be designed in accordance with the CDOT M&S Standards, and Item No. 2 of the Design Data of CDOT s S A is applicable. The soils should be assumed cohesive, have a minimum unit weight of 110 pounds per cubic foot, and cohesion of 750 psf. Signal pole foundations should have a minimum (embedment) length of 18½ feet for cohesive soil, and installation should be in accordance with Section 503 Drilled Caissons of the CDOT standard specifications. The following additional recommendations should be observed: 1) Groundwater levels are expected to be variable and potentially higher than where encountered, especially during the springtime or with heavy runoff or precipitation. Most of the soils encountered are low permeability clays with layers of poorly graded sands. If groundwater is encountered during construction, measures to stabilize the drilled hole may be needed, including the use of flow-fill and re-drilling as described in Item 16 in the General Notes of the M&S Standards. Groundwater flow into the shaft during drilling could be significant if sand layers are encountered. 2) Concrete should be placed in drilled shafts the same day they are drilled/re-drilled. Failure to place concrete the day of drilling will result in degradation of the material bearing conditions and a requirement for additional penetration. The amount of additional penetration will be a function of how long the hole is left open and whether or not water accumulates during the inactive time. If the drilled shaft is left open overnight, this office should be contacted for evaluation of additional penetration. 3) Care should be taken to prevent forming mushroom shapes at the top of the drilled shafts. The use of sonotube of the appropriate shaft diameter and/or mud slurry may be needed. 4) The drilling contractor should mobilize equipment of sufficient size and operating condition to penetrate the materials and to achieve the required penetration. 7.4 Lateral Capacity Parameters The following recommendations are based on the structural engineer using the computer program LPILE for lateral load analysis. Data presented below is based on our judgment and the user and technical manuals for LPILE Plus 6.0. Effective Unit Weight (pcf) Cohesion Friction angle (deg) Material Type Cu k-value ε50 (p-y Curve Model Type) (psf) (pci) Artificial Fill (Stiff Clay w/out Free Water) CDOT Class 1 Structure Backfill (Sand, Reese) Natural Clay (Stiff Clay w/out Free Water) Weathered Claystone (Stiff Clay w/out Free Water) , Claystone Bedrock (Stiff Clay w/out Free Water) 125 6, , ε50 = strain at 50% of peak strength Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 13 of 25

17 Reductions in lateral capacity for loading perpendicular to the line of shafts will not be required if center to center spacing of 5 shaft/pile diameters or more between adjacent drilled shafts/piles is maintained. For lateral loads parallel to the line of shafts/piles, reduction in lateral capacity is necessary at a spacing less than 6 diameters. LPILE uses p-multipliers to account for reduced capacity of closely spaced drilled shafts or piles. Data presented below are based on information published in the 2014 AASHTO LRFD Bridge Design Specifications 7 th Edition Manual. A sketch of the loading and how the rows are referenced is also shown. P-Multipliers (Pm) for Drilled Shafts & Driven Pile Foundation p-multiplier for LPILE Center to Center Row 3 and Spacing Row 1 Row 2 Higher 3B B B= Diameter of Shaft or Pile 8.0 RETAINING STRUCTURES We understand that cast-in-place cantilever (CIP) wing walls are anticipated for use at the widened West Fork Second Creek structure. Wing walls at the West Fork Second Creek should be supported by the same foundation type as the bridge. Walls and retaining structures which are laterally supported and can be expected to Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 14 of 25

18 undergo only a slight amount of deflection should be designed for lateral earth pressures based on the "at-rest" earth pressure condition. Walls which rotate and/or deflect sufficiently to mobilize the internal soil strength of the wall backfill may be designed for the "active" earth pressure condition. The natural clay soils encountered onsite are not suitable for use as wall backfill. Imported structure backfill material should meet CDOT standard specifications for Class 1 material. The following allowable earth pressure coefficients are recommended for imported CDOT Class 1 structure backfill material. Material Active (K a) At-Rest (K o) Passive (K p) T Unit Weight (pcf) Friction Angle (deg) Imported Class The above values are for backfill placed and compacted in accordance with the CDOT standard specifications. Lateral wall movements or rotation equal to 0.5% of the wall height are typically required to develop the active case for granular backfill, whereas lateral movement equal to at least 1% of the wall height is required to establish full passive resistance. Suitable factors of safety should be applied to the above ultimate values to limit strain needed to reach ultimate strength, particularly in the case of passive resistance. Equivalent fluid unit weights may be assumed as follows: Above groundwater: eq = T x K a,o,p Below groundwater: eq = ( T 62.4 ) x K a,o,p where: T = soil total unit weight K a,o,p = appropriate earth pressure coefficient The above parameters are for a horizontal backfill and no surcharge loading. Retaining structures should be designed for appropriate surcharge pressures such as from traffic, snow storage, etc. The buildup of water behind a wall will also increase the lateral pressures. A drainage system should be included in the wall design to prevent hydrostatic pressure buildup, unless the wall is designed to accommodate the additional pressure. Placement and compaction of backfill should be in accordance with the CDOT standard specifications. Care should be taken not to over compact the backfill or use large equipment, which may cause excessive lateral loading against the walls. Settlement of wall backfill is estimated at approximately 1 inch and should occur during construction, assuming CDOT Class 1 Structure Backfill material is used and provided the base of the backfill and embankment area is prepared in accordance with Section 10.0 Site Grading and Settlement. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 15 of 25

19 9.0 UNDERDRAIN SYSTEM Below grade structures should be provided with an underdrain system which will help reduce the buildup of hydrostatic pressures. The underdrain system should consist of a perforated PVC pipe surrounded by free draining granular material placed at the bottom of the wall backfill and sloped at a minimum 2% grade to suitable gravity outlets. Free draining granular material used in the drain system should conform to Class B filter material as specified in the CDOT standard specifications. Animal guards should be considered for use at the pipe outlets SITE GRADING AND SETTLEMENT Excavation of the onsite materials should be possible with conventional heavy duty equipment. The re-use of onsite materials will be a function of where the material is taken from and the intended use. Existing vegetation, debris, and any other deleterious materials should be stripped and removed from all proposed pavement, walkway, and fill areas. Exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. Fill should be placed and compacted in accordance with the CDOT standard specifications. Flatwork areas should be stripped of existing vegetation and topsoil, uniformly scarified to a depth of 8 inches, moisture conditioned and compacted in accordance with the CDOT standard specifications. Prepared subgrade areas should be proof rolled per the CDOT standard specifications and areas that deform, rut, or pump excessively should be excavated and replaced with properly placed and compacted non-expansive granular material. Material meeting CDOT Class 1 grading requirements should be imported for retaining wall backfill. Permanent fill slopes up to 15 feet high should be constructed no steeper than 3 horizontal to 1 vertical grade, provided the fills are properly compacted and drained. The ground surface underlying proposed fills should be carefully prepared by removing all organic matter and oversized material (greater than 6 inches maximum dimension), scarifying to a depth of 8 inches and re-compacting in accordance with the CDOT standard specifications. The exposed surface should be proof-rolled in accordance with Section of the CDOT standard specifications prior to placement of any new fill. Settlement of properly compacted embankments construction of properly compacted material similar to that encountered onsite should be on the order of 1% to 2% of the embankment height. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 16 of 25

20 Permanent cut slopes and other stripped areas should be protected against erosion by re-vegetation or other methods. Cut slopes up to 10 feet high should be possible provided the slopes do not exceed 3 horizontal to 1 vertical and seepage is not encountered. If seepage is encountered we should be advised for further evaluation. Proper surface drainage should be provided around all permanent cuts to direct surface runoff away from the cut face. No formal slope stability analyses were performed to evaluate the slopes recommended above. Published literature and our experience with similar cuts and fills indicate the recommended slopes have adequate factors of safety. Excavations: The excavations for this project are anticipated to be primarily in the soft to medium stiff natural clay soils. Excavations in these materials should be possible with conventional excavation equipment, however, excavations below the groundwater level will likely require a shoring system to provide safe working conditions as these materials are generally not stable at slopes steeper than approximately 3H:1V, particularly if a surcharge (e.g. traffic) is present above the excavation. If sloped excavations are used, stockpiled material should be placed no closer than 10 feet from the top of the excavation, or no closer than three times the depth of the excavation, whichever is greater. Sloped excavations should conform to applicable OSHA regulations and the contractor should assume responsibility for excavations that are safe for workers; excavations are anticipated to be in Type C soils, per the OSHA soil classification system. Excavations are particularly susceptible to localized instabilities if seepage is encountered. Sheet piles could be considered for excavation support during construction and could serve as a permanent retention system. Shoring, sheeting, and bracing systems should be designed be a professional engineer registered in the State of Colorado. Settlement: In fill areas, two types of embankment settlement will occur: settlement due to consolidation of the new embankment material itself due to its own weight, and settlement of the foundation soils supporting the embankment (manifested by movement of the embankment). If the onsite clay soils are used to construct the embankment, settlement due to fill consolidation could range from 1% to 3% of the embankment height, although depending on a number of variables could be higher, and the time required for primary settlement could take a significant amount of time (several months). Settlement potential and time required for settlement to occur for new embankment fill can be reduced by using a higher quality material. An additional 2 to 3 inches of settlement due to consolidation of the embankment soils should be expected and will happen for a significant amount of time after construction. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 17 of 25

21 High embankments or walls (greater than about 12 feet high) should be constructed as early in the construction sequence as possible, and be monitored with survey points to evaluate the settlement. Final grading for roadways or construction of other structures should be done after settlement is essentially complete. Dewatering: During our field exploration, groundwater was encountered in Borings B-1 and B-2 at an elevation approximately equal to the water level in the adjacent West Fork of Second Creek (i.e. at a depth of approximately 5 feet below existing grade). Depending on the depth and seasonal conditions, groundwater may be encountered in excavations. The contractor should be experienced with the types of surface and subsurface conditions that exist at this site and anticipate that groundwater flow rates into excavations that are below the groundwater level may be high. If excavations are conducted during the spring and early summer months, seasonal runoff may rapidly increase the groundwater level and the contractor may need to be prepared with sufficient equipment to accommodate a rapid rise of groundwater PAVEMENT DESIGN A pavement section is a layered system designed to distribute concentrated traffic loads to the subgrade without overstressing the subgrade soils. Performance of the pavement structure is a function of a number of factors including, but not limited to, the physical properties of the subgrade soils, drainage, and traffic loading. The pavement sections presented in this report for Tower Road are based on laboratory test results and the Metropolitan Government Pavement Engineers Council Design Standards and Construction Specifications (MGPEC standard specifications). We understand that functional overlay (mill and fill) is planned for portions of Tower Road which does not require a pavement design. MGPEC designs for Portland Cement Concrete Pavement (PCCP) and Hot Mix Asphalt Pavement (HMAP) are presented in Section New PCCP sections for the proposed westbound Pena Boulevard ramps are provided in Section 11.2, based on the CDOT procedures and using the AASHTO 1998 Rigid Pavement Design Guide. Widened portions of the eastbound Pena Boulevard off ramp will be constructed to match the existing pavement section and will not require a pavement design TOWER ROAD - MGPEC PAVEMENT DESIGN Design Traffic Loading: The 18-kip Equivalent Single Axle Load (ESAL) is the equivalent 18,000 pound single axle loading for different vehicle types, and the design period ESAL is the total equivalent loading applied to Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 18 of 25

22 the pavement for the design period. A 20 year design life is used in the MGPEC procedure, which requires an estimate of the number of 18-kip ESALs that will be applied to the pavement structure during the 20 year project design life. A traffic projection study for this project was prepared by Felsburg, Holt, & Ullevig (FHU) entitled Tower Road/Pena Boulevard Interchange Modifications dated October 13, From that report, FHU provided 2040 Average Daily Traffic Volume (ADT) for Tower Road that ranged from 57,000 vehicles per day south of Pena Boulevard to approximately 85,000 vehicles per day north Pena Boulevard. FHU also provided the truck traffic distribution, based on recently collected vehicle classification data for Tower Road north of Pena Boulevard. The design ESAL calculations were based on the opening day ADT of 27,500 vehicles per day and the projected 2040 ADT of 85,000 vehicles per day provided by FHU. A 20 year growth factor of 2.82 was calculated for Tower Road. The following MGPEC vehicle factors and traffic distribution were utilized for ESAL calculations: Vehicle Type MGPEC Vehicle Equivalency Factor % of Traffic Passenger Vehicles Busses Two Axle Six Tire Three Axle Single Combination Unit Truck A design lane factor of 45% was applied to Denver portion of the project corridor, assuming 2 travel lanes in each direction. Applying the MGPEC vehicle equivalency factors, a 20 year design ESAL value (ESAL 20) of 25,294,286 was calculated for Tower Road in the Denver portion of the project corridor. Subgrade Soil Strength: Gradation and Atterberg limits results were used to determine AASHTO classifications for the subgrade soil samples; the classifications give qualitative information on the suitability of the material for use as pavement support. The soils tested generally consisted of clayey sand to fat clay, with AASHTO classifications ranging from A-6 to A-7-6, and Group Indices of 0 to 36. The classifications and Group Indices indicate that the soils have predominantly poor pavement support capabilities. MGPEC design procedures utilize correlations and equations for Resilient Modulus to quantify subgrade pavement support characteristics. For sandy subgrades, the MGPEC equations are related to the R-value of the soils, whereas for clayey subgrades, the MGPEC equations are related to the factored unconfined compressive strength (q u). The MGPEC Equation 7 for clay soils (AASHTO A-7-6) is: M r=3.13(q u), where q u is the remolded, unconfined strength. The MGPEC procedures state that the resulting resilient modulus obtained from the above equations should be reduced by 25% unless: (1) a subdrain system is provided and properly maintained, (2) the Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 19 of 25

23 subgrade is permeable (K>1,000 ft/year), (3) for rural pavements with designated drainage ditches, or (4) the subgrade is gneiss or granitic in nature. As per the MGPEC pavement design guidelines, a resilient modulus (M r) of 10,604 pounds per square inch (psi) was calculated, based on a remolded unconfined compressive strength of 3,388 psf and using Equation 7 of the MGPEC design manual for A-7-6 soils, the highest AASHTO soil classification encountered during our subsurface exploration. A 25% reduction was applied because a subdrain system is not expected to be installed along Tower Road, which yields a design resilient modulus of 7,953 psi. Any imported soils used as pavement subgrade should have similar or better strength characteristics. Pavement Thickness Recommendations: MGPEC software calculated the following composite HMAP over Chemically Stabilized Subgrade (CSS) and PCCP sections for Tower Road. The pavement design printout and MGPEC Form #9 are included in Appendix A. Location Tower Road Pavement Type Pavement Thickness (in) Aggregate Base Course (ABC) Thickness (in) HMAP over 12 inches CSS 12.0 N/A PCCP Full depth* Note: (*) Indicates 12 inches of CSS is recommended for subgrade stabilization. The MGPEC procedure does not provide fatigue equivalent combination sections for HMAP over an aggregate base course when the full depth HMAP section is greater than 7 inches. A minimum 4 inch layer of Class 6 aggregate base course is recommended for support of new concrete pavement. This aggregate layer will help reduce the potential loss of subgrade support caused by migration of fines through construction joints. Loss of subgrade support can reduce the service life of the pavement. Aggregate base material should meet specifications in accordance with Item 7 of the MGPEC specifications and have a minimum R-value of 78. We understand that HMAP is the preferred alternative for mainline Tower Road, and PCCP is being considered for the new westbound Pena Boulevard ramps. PCCP may also be considered for the intersections with the Pena Boulevard ramps along Tower Road, to provide continuity with the PCCP ramps and Pena Boulevard. If chemical stabilization of the pavement subgrade along Tower Road is performed, a bond breaker should be placed below the concrete pavement to help reduce the risk of reflection cracking. The bond breaker may consist of a 4 inch layer of aggregate base course, or one lift of asphalt pavement PENA BOULEVARD RAMPS CDOT PAVEMENT DESIGN Design Traffic Loading: For concrete pavements, a 30 year design life is used in the CDOT procedure, which requires an estimate of the number of 18-kip ESALs that will be applied to the pavement structure during the Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 20 of 25

24 30 year project design life. A traffic projection study for this project was prepared by Felsburg, Holt, & Ullevig (FHU). The design ESAL calculations were based on the daily traffic volume forecasts provided by FHU, summarized in the following table. Segment Opening Day ADT Future (2040) ADT 30 Year Design ADT Pena Boulevard westbound exit ramp 5,100 11,500 9,275 Pena Boulevard westbound entrance ramp 9,900 22,000 17,793 It was assumed that construction would be complete and the ramps would be put into service in A growth factor of 2.1 was calculated for the westbound Pena Boulevard ramps and was used to calculate the 30 year design ADT. Based on recently collected vehicle classification data for Tower Road north of Pena Boulevard and provided by FHU, the following CDOT vehicle equivalency factors and traffic distribution were used to calculate the design ESALs: Vehicle Type CDOT Rigid Pavement Vehicle Equivalency Factor % of Traffic Passenger Vehicle Single Unit Truck Combination Unit Truck A design lane factor of 100% was used, which corresponds to a single travel lane for the new exit and entry ramps. Applying the CDOT vehicle equivalency factors, a 30 year design ESAL value (ESAL 30) of 16,778,597 was calculated for the new westbound Pena Boulevard entrance ramp, and an ESAL 30 of 8,751,766 was calculated for the westbound Pena Boulevard exit ramp. Subgrade Soil Strength and Design Parameters: Laboratory test results indicate that the majority of the existing pavement subgrade soils have AASHTO Classifications of A-6 to A-7-6 with Group Indices ranging from 0 to 36. Laboratory test results indicate a CBR value of 1.8% for the composite bulk sample remolded to approximately 95% of the maximum dry density. The CBR value corresponds to a static K-value of 45. An alternative pavement section was calculated based on the use of imported granular fill material placed in the upper four feet of the pavement subgrade. The following additional design parameters were also used: General Initial Serviceability 4.5 Terminal Serviceability 2.5 Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 21 of 25

25 Reliability Level 90% Soils Elastic Modulus of Base (Class 6 ABC, psi) 15,000 Slab-Base Friction Factor 1.4 Subgrade Static K-value (psi/in) onsite 45 Subgrade Static K-value (psi/in) import 200 Concrete Overall Standard Deviation day Mean PCCP Modulus of Rupture (psi) 650 PCCP Elastic Modulus of Slab (psi) 3,400,000 Poisson s Ratio for Concrete 0.15 Pavement Thickness Recommendations: Portland Cement Concrete Pavement (PCCP) thickness sections were calculated using the AASHTO 1998 Rigid Pavement Design Guide. The recommended pavement thickness sections are shown below (computer printouts are in the attached Appendix B). Segment WB exit ramp WB entrance ramp Subgrade Type PCCP Thickness (in) Aggregate Base Course (ABC) Thickness (in) Onsite soils 10 6 Imported fill 9½ 6 Onsite soils 11 6 Imported fill 10½ PAVEMENT MATERIALS AND SUBGRADE RECOMMENDATIONS Hot Mix Asphalt Pavement (HMAP): HMAP materials should consist of a bituminous plant mix composed of a mixture of aggregate and bituminous material that meets the requirements of a job-mix formula established by a qualified engineer. The following grading and binder types are recommended for this project: Tower Road Top Lift (2 inches) SMA PG (½ Mix) Lower Lifts Grading S (100) PG Grading S (100) PG (optional) SMA is a gap graded mix designed to maximize rutting resistance through stone on stone contact. The use of SMA is often reserved for Principal Arterial, Freeway or Interstate with high traffic. The lift thickness should not exceed 4 times the nominal aggregate size. Mix design and construction should be performed in accordance with Item 9 of the MGPEC standard specifications. Portland Cement Concrete Pavement (PCCP): PCCP pavements should meet requirements specified for Class P concrete in accordance with the CDOT standard specifications. PCCP sections assume the use of dowels Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 22 of 25

26 for transverse joints and that the pavement is tied to concrete shoulders or curbs. Dowels should be a minimum 1¼ inches in diameter for the Pena Boulevard westbound exit ramp and a minimum 1½ inch diameter for the Pena Boulevard westbound entrance ramp and for Tower Road, based on Faulting criteria in the AASHTO Supplemental Rigid Pavement Design Guide. Aggregate Base Course (ABC): Material should meet specifications in accordance with Item 7 of the MGPEC standard specifications and have a minimum R-value of 78. The material should be compacted to at least 95% of the maximum density as determined by AASHTO T-180. A minimum 4 inch thick layer of ABC should be placed below concrete pavement if chemical stabilization of the subgrade soils is performed, which will act as a bond breaker and should help reduce reflection cracking. Alternatively, one lift of HMAP may also be considered for use as a bond breaker for PCCP over chemical stabilized subgrade. Subgrade Preparation: The laboratory test results indicate that much of the onsite soils are clays that exhibited a low to moderate swell potential when subjected to wetting. To help mitigate the risk of pavement damage caused by expansive subgrade, we recommend that the new pavement along Tower Road be supported by at least 2 feet of moisture treated subgrade, and that new pavement for the new westbound Pena Boulevard ramps be supported by at least four feet of moisture treated subgrade. Subgrade soils should be excavated, moisture treated to -1% to +3% of optimum moisture content as determined by a standard Proctor, and be recompacted to at least 95% of the maximum standard Proctor density. Some of the onsite clay soils may be difficult to stabilize when wet of optimum. Soft or yielding subgrade should be chemically stabilized within at least the upper 12 inches. The use of lime, fly ash, cement, or geogrids may be considered to stabilize yielding subgrades. Alternatively, non-expansive granular fill material may be placed in the over-excavation for support of pavements, and may not require chemical stabilization. If granular fill material is use, edge drains should be considered to collect and divert water from the pavement subgrade, especially in the cut areas. Any old pavement, debris or any otherwise unsuitable materials should be removed from the pavement subgrade and replaced with soils meeting the minimum strength requirements. New fill needed for support of pavements should be non-expansive and satisfy the minimum strength requirements. Chemically Stabilized Subgrade (CSS): Chemically Stabilized Subgrade (CSS) should meet the requirements of Item 5 of the MGPEC standard specifications. A mix design to stabilize the subgrade soils should be performed if the composite HMAP over CSS option is selected. For estimating purposes, 4% quick lime for the mix design may be assumed. The final subgrade soils can be sampled and the appropriate mix established. Several trial batches using lime, lime-fly ash, and/or cement kiln dust as stabilizing agents may be needed. The CSS should Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 23 of 25

27 provide for a stable subgrade having an unconfined compressive strength of at least 160 psi and the CSS should extend beneath curb and gutter. Proof-Roll: Prior to paving, the subgrade including CSS should be proof-rolled with a heavily loaded pneumatic tired vehicle, as described in Section of the MGPEC specifications. Areas of the subgrade that rut or deflect excessively under the wheel loads should be removed and replaced prior to paving. Proof-rolled areas should be paved within 48 hours unless affected by precipitation, construction traffic, or otherwise disturbed. The contractor should anticipate subgrade conditions that vary from optimum moisture, and the addition of water or drying of the subgrade soils to achieve proper moisture conditions will be needed. Areas that are noticeably dry should be moisture conditioned and compacted. Drainage, Frost Potential, and Utilities: The collection and diversion of surface drainage away from paved areas is extremely important for the satisfactory performance of the pavement. The design of surface drainage should be carefully considered to remove all water from the roadway paved areas. Groundwater was encountered at depths at which a separate pavement subsurface drain should not be needed. However, if imported granular fill material is used for pavement support, subsurface pavement drains should be considered. The predominant soil types are sandy lean to fat clay that are moderately susceptible to frost heave. However, frost heave potential may be reduced with proper surface drainage and construction control. Major utilities, such as gas, water, and sewer should be placed prior to paving. Trench backfill should be properly placed and compacted to reduce differential settlement and subsequent distress to the pavement structure. Maintenance: Periodic maintenance of paved areas will extend pavement life. The scheduled maintenance programs listed in Section 5 of the MGPEC specifications should be followed for Commercial, Industrial, and Arterial pavement designs for HMAP and PCCP LIMITATIONS This report has been prepared in accordance with generally accepted geotechnical engineering practices used in this area, and has been prepared for design purposes. The conclusions and recommendations submitted in this report are based upon the data obtained from the borings drilled at the approximate locations shown on Figures 1-A and 1-B. The nature and extent of the variations between borings may not become evident until excavation is Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 24 of 25

28 performed. If during construction, soil, bedrock, fill, or groundwater conditions appear to be different from those described, this office should be advised so that re-evaluation of our recommendations may be made. On-site observation and testing of construction materials is recommended. Our professional services were performed using that degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical engineers practicing in this or similar localities. No warranty expressed or implied is made. We prepared the report as an aid in the design of the proposed project. This report is not a bidding document. Any contractor reviewing this report must draw his or her own conclusions regarding site conditions and specific construction techniques to be used on this project. This report is for the exclusive purpose of providing geotechnical engineering information and recommendations. The scope of services for this project does not include environmental assessment of the site or identification of contaminated or hazardous materials or conditions. If the owner is concerned about the potential for such contamination, other studies should be undertaken. Subsurface Exploration and Pavement Design Report (revised September 6, 2017) Tower Road at Pena Boulevard Improvements (G ) Page 25 of 25

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34 PERCENT SWELL(+)/COMPRESSION(-) PERCENT SWELL(+)/COMPRESSION(-) SWELL-COMPRESSION TEST 2 1 Expansion under constant pressure due to wetting LOAD (PSF) 2 Sample Location Boring B-1 Dry Density 70 pcf Sample Depth Sample Description 14 feet Claystone bedrock Moisture Content Volume Change 48.2 % 1.5 % USCS Classification Swell Pressure 3,000 psf AASHTO Classification 1 0 Expansion under constant pressure due to wetting LOAD (PSF) Sample Location Sample Depth Sample Description USCS Classification AASHTO Classification Boring B-2 Dry Density 71 pcf 19 feet Claystone bedrock Moisture Content Volume Change 49.8 % 1.3 % Swell Pressure 1,500 psf GEOCAL, INC. Tower Road and Pena Blvd. SWELL - COMPRESSION TEST RESULTS JOB NO. FIGURE NO. G

35 PERCENT SWELL(+)/COMPRESSION(-) PERCENT SWELL(+)/COMPRESSION(-) 2 SWELL-COMPRESSION TEST 1 0 Expansion under constant pressure due to wetting LOAD (PSF) Sample Location Boring P-1 Dry Density 105 pcf Sample Depth Sample Description 4(b) feet Fat clay, fill Moisture Content Volume Change 20.3 % 0.7 % USCS Classification CH Swell Pressure 0 psf AASHTO Classification A-7-6(29) Expansion under constant pressure due to wetting LOAD (PSF) Sample Location Sample Depth Sample Description USCS Classification AASHTO Classification P-3 Dry Density 107 pcf 1 foot Sandy lean clay, fill Moisture Content Volume Change 19.5 % 0.3 % CL Swell Pressure 0 psf A-6(12) GEOCAL, INC. Tower Road and Pena Blvd. SWELL - COMPRESSION TEST RESULTS JOB NO. FIGURE NO. G

36 PERCENT SWELL(+)/COMPRESSION(-) PERCENT SWELL(+)/COMPRESSION(-) SWELL-COMPRESSION TEST Expansion under constant pressure due to wetting LOAD (PSF) 4 Sample Location Boring P-1 Dry Density 108 pcf Sample Depth Sample Description 1 foot Fat clay, fill Moisture Content Volume Change 19.2 % 2.0 % USCS Classification CH Swell Pressure 260 psf AASHTO Classification A-7-6(36) 3 2 Expansion under constant pressure due to wetting LOAD (PSF) Sample Location Sample Depth Sample Description USCS Classification AASHTO Classification Boring P-6 Dry Density 105 pcf 1 foot Sandy lean clay Moisture Content Volume Change 8.8 % 3.9 % CL Swell Pressure 1,200 psf A-6(8) GEOCAL, INC. Tower Road and Pena Blvd. SWELL - COMPRESSION TEST RESULTS JOB NO. FIGURE NO. G

37 PERCENT SWELL(+)/COMPRESSION(-) PERCENT SWELL(+)/COMPRESSION(-) SWELL-COMPRESSION TEST Expansion under constant pressure due to wetting LOAD (PSF) 4 Sample Location Boring P-5 Dry Density 105 pcf Sample Depth Sample Description 4 feet Sandy fat clay Moisture Content Volume Change 15.8 % 3.3 % USCS Classification CH Swell Pressure psf AASHTO Classification A-7-6(22) 3 2 Expansion under constant pressure due to wetting LOAD (PSF) Sample Location Sample Depth Sample Description USCS Classification AASHTO Classification Boring P-12 Dry Density 103 pcf 1 feet Fat clay with sand Moisture Content Volume Change 20.0 % 3.5 % CH Swell Pressure 1,200 psf A-7-6(21) GEOCAL, INC. Tower Road and Pena Blvd. SWELL - COMPRESSION TEST RESULTS JOB NO. FIGURE NO. G

38 PERCENT SWELL(+)/COMPRESSION(-) PERCENT SWELL(+)/COMPRESSION(-) SWELL-COMPRESSION TEST 2 1 Expansion under constant pressure due to wetting LOAD (PSF) 2 Sample Location Boring I-1 Dry Density 109 pcf Sample Depth Sample Description 1 foot Silty sand, fill Moisture Content Volume Change 22.0 % 1.2 % USCS Classification SM Swell Pressure 1,600 psf AASHTO Classification A-6(3) 1 Expansion under constant pressure due to wetting LOAD (PSF) Sample Location Sample Depth Sample Description USCS Classification AASHTO Classification Boring P-11 Dry Density 116 pcf 4 feet Lean clay with sand Moisture Content Volume Change 15.6 % 1.7 % CL Swell Pressure 1,900 psf A-6(14) GEOCAL, INC. Tower Road and Pena Blvd. SWELL - COMPRESSION TEST RESULTS JOB NO. FIGURE NO. G

39 PERCENT SWELL(+)/COMPRESSION(-) PERCENT SWELL(+)/COMPRESSION(-) ONE DIMENSIONAL CONSOLIDATION TEST LOAD (PSF) Sample Location Boring B-1 Dry Density 104 pcf Sample Depth 4 feet Moisture Content 21.3 % Sample Description Lean clay with sand Est. Preconsol. USCS Classification AASHTO Classification CL A-6(12) Stress Sample Location Sample Depth Sample Description USCS Classification AASHTO Classification LOAD (PSF) Boring B-2 Dry Density 98 pcf 9 feet Moisture Content 26.4 % Sandy lean clay Est. Preconsol. CL Stress A-6(9) GEOCAL, INC. Tower Road and Pena Blvd. CONSOLIDATION TEST RESULTS JOB NO. FIGURE NO. G a

40 deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) Tower Road Widening Load Increment: 0.5 KSF Dial Dial Time^.5 Time Reading Change Time-Consolidation Test, 4' (Load = 1 ksf) log of Time (minutes) Time-Consolidation Test, 4' (Load = 1 ksf) Square Root of Time (minutes^.5) Load Increment: 1 KSF Dial Dial Time^.5 Time Reading Change Time-Consolidation Test, 4' (Load = 3 ksf) log of Time (minutes) Time-Consolidation Test, 4' (Load =3 ksf) Square Root of Time (minutes^.5) Load Increment: 3 KSF Dial Dial Time^.5 Time Reading Change Time-Consolidation Test, 4' (Load = 5 ksf) log of Time (minutes) Time-Consolidation Test, 4' (Load = 5 ksf) Square Root of Time (minutes^.5) Figure 9b

41 deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) deformation (10-4 inches) Tower Road Widening Load Increment: 1 KSF Dial Dial Time^.5 Time Reading Change Time-Consolidation Test, 9' (Load = 1 ksf) log of Time (minutes) Time-Consolidation Test, 9' (Load = 1 ksf) Square Root of Time (minutes^.5) Load Increment: 3 KSF Dial Dial Time^.5 Time Reading Change Time-Consolidation Test, (Load = 3 ksf) log of Time (minutes) Time-Consolidation Test, (Load =3 ksf) Square Root of Time (minutes^.5) Load Increment: 5 KSF Dial Dial Time^.5 Time Reading Change Time-Consolidation Test, (Load = 5 ksf) log of Time (minutes) Time-Consolidation Test, (Load = 5 ksf) Square Root of Time (minutes^.5) Figure 9c

42 Gradation Test Results in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FINER GRAIN SIZE - mm. % +3" % Gravel % Sand % Silt % Clay LL PL D 85 D 60 D 50 D 30 D 15 D 10 C c C u Material Description USCS AASHTO lean clay with sand CL A-6(12) claystone bedrock sandy lean clay CL A-6(9) sandstone bedrock silty sand, fill SM A-6(3) Project No. G Client: Core Consulting Remarks: Project: Tower & Pena Blvd Ramps Location: Boring B-1 Depth: 4 feet Sample Number: Location: Boring B-1 Depth: 14 feet Sample Number: Location: Boring B-2 Depth: 9 feet Sample Number: Location: Boring B-2 Depth: 19 feet Sample Number: Location: Boring I-1 Depth: 1 foot Sample Number: GEOCAL, INC. Figure 10

43 Gradation Test Results in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FINER GRAIN SIZE - mm. % +3" % Gravel % Sand % Silt % Clay LL PL D 85 D 60 D 50 D 30 D 15 D 10 C c C u Material Description USCS AASHTO fat clay CH A-7-6(36) fat clay, fill CH A-7-6(29) sandy lean clay, fill CL A-6(12) lean clay with sand, fill CL A-7-6(15) sandy lean clay CL A-6(8) Project No. G Client: Core Consulting Remarks: Project: Tower & Pena Blvd Ramps Location: Boring P-1 Depth: 1 foot Sample Number: Location: Boring P-1 Depth: 4(b) feet Sample Number: Location: Boring P-3 Depth: 1 foot Sample Number: Location: Boring P-3 Depth: 1-5 feet Sample Number: Location: Boring P-4 Depth: 1 foot Sample Number: GEOCAL, INC. Figure 11

44 Gradation Test Results in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FINER GRAIN SIZE - mm. % +3" % Gravel % Sand % Silt % Clay LL PL D 85 D 60 D 50 D 30 D 15 D 10 C c C u Material Description USCS AASHTO sandy fat clay CH A-7-6(22) sandy lean clay CL A-6(8) clayey sand with gravel, fill SC A-6(2) clayey sand, fill SC A-6(3) sandy lean clay CL A-6(4) Project No. G Client: Core Consulting Remarks: Project: Tower & Pena Blvd Ramps Location: Boring P-5 Depth: 4 feet Sample Number: Location: Boring P-6 Depth: 1 foot Sample Number: Location: Boring P-7 Depth: 1-5 feet Sample Number: Location: Boring P-9 Depth: 1-5 feet Sample Number: Location: Boring P-10 Depth: 1-5 feet Sample Number: GEOCAL, INC. Figure 12

45 Gradation Test Results in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FINER GRAIN SIZE - mm. % +3" % Gravel % Sand % Silt % Clay LL PL D 85 D 60 D 50 D 30 D 15 D 10 C c C u Material Description USCS AASHTO lean clay with sand CL A-6(14) fat clay with sand CL A-7-6(21) clayey sand, fill SC A-2-6(0) sandy lean clay CL A-6(7) clayey sand SC A-6(4) Project No. G Client: Core Consulting Remarks: Project: Tower & Pena Blvd Ramps Location: Boring P-11 Depth: 4 feet Sample Number: Location: Boring P-12 Depth: 1-5 feet Sample Number: Location: Boring P-13 Depth: 1-5 feet Sample Number: Location: Boring P-14 Depth: 1-5 feet Sample Number: Location: Boring P-15 Depth: 1-5 feet Sample Number: GEOCAL, INC. Figure 13

46 Gradation Test Results in. 3 in. 2 in. 1½ in. 1 in. ¾ in. ½ in. 3/8 in. #4 #10 #20 #30 #40 #60 #100 #140 # PERCENT FINER GRAIN SIZE - mm. % +3" % Gravel % Sand % Silt % Clay LL PL D 85 D 60 D 50 D 30 D 15 D 10 C c C u Material Description USCS AASHTO lean clay with sand CL A-7-6(16) sandy lean clay CL A-6(8) Project No. G Client: Core Consulting Remarks: Project: Tower & Pena Blvd Ramps Loc.: Borings P11 & P12 combined Depth: 1-5 feet Sample No.: Loc.: Borings P14 & P15 combined Depth: 1-5 feet Sample No.: GEOCAL, INC. Figure 14

47 Moisture-Density Relationship Test Results Project No.: G Date: Project: Client: Tower & Pena Blvd Ramps Core Consulting Location: Borings P11 & P12 combined Sample Number: Depth: 1-5 feet Remarks: Description: lean clay with sand MATERIAL DESCRIPTION Classifications - USCS: CL AASHTO: A-7-6(16) Nat. Moist. = Sp.G. = Liquid Limit = 41 Plasticity Index = 24 % < No.200 = 73 % Maximum dry density = pcf Optimum moisture = 18.6 % TEST RESULTS 140 Test specification: AASHTO T Method A Standard 130 Dry density, pcf % SATURATION CURVES FOR SPEC. GRAV. EQUAL TO: Water content, % Figure GEOCAL, INC. 15

48 Moisture-Density Relationship Test Results Project No.: G Date: Project: Client: Tower & Pena Blvd Ramps Core Consulting Location: Borings P14 & P15 combined Sample Number: Depth: 1-5 feet Remarks: Description: sandy lean clay MATERIAL DESCRIPTION Classifications - USCS: CL AASHTO: A-6(8) Nat. Moist. = Sp.G. = Liquid Limit = 34 Plasticity Index = 17 % < No.200 = 61 % Maximum dry density = pcf Optimum moisture = 14.3 % TEST RESULTS 140 Test specification: AASHTO T Method A Standard 130 Dry density, pcf % SATURATION CURVES FOR SPEC. GRAV. EQUAL TO: Water content, % Figure GEOCAL, INC. 16

49 Moisture-Density Relationship Test Results Project No.: G Date: Project: Client: Tower & Pena Blvd Ramps Core Consulting Location: Boring P-3 Sample Number: Depth: 1-5 feet Remarks: Description: lean clay with sand, fill MATERIAL DESCRIPTION Classifications - USCS: CL AASHTO: A-7-6(15) Nat. Moist. = Sp.G. = Liquid Limit = 41 Plasticity Index = 23 % < No.200 = 72 % Maximum dry density = pcf Optimum moisture = 18.3 % TEST RESULTS 140 Test specification: AASHTO T Method A Standard 130 Dry density, pcf % SATURATION CURVES FOR SPEC. GRAV. EQUAL TO: Water content, % Figure GEOCAL, INC. 17

50 UNCONFINED COMPRESSION TEST Compressive Stress, psf Axial Strain, % Sample No. Unconfined strength, psf Undrained shear strength, psf Failure strain, % Strain rate, in./min. Water content, % Wet density, pcf Dry density, pcf Saturation, % Void ratio Specimen diameter, in. Specimen height, in. Height/diameter ratio Description: lean clay with sand, fill LL = 41 PL = 18 PI = 23 GS= 2.6 Type: Project No.: G Date Sampled: Remarks: Remolded at 95% of MDD and 2% over OM Figure Client: Core Consulting Project: Tower & Pena Blvd Ramps Location: Boring P-3 Sample Number: Depth: 1-5 feet UNCONFINED COMPRESSION TEST GEOCAL, INC.

51 Unconfined Compressive Strength of Cohesive Soils Force (-Lbs) vs Extension (-Inches) Specimen ID Test Number Report Number Test Date UC /27/ :53:21 AM Test Results Peak Load (lbs) Shear. Str. (lbs/ft²) Comp. Str. (lbs/ft²) 2,150 4, Testing Machine STM Load Cell S/N (IFI548933), Units (LBS ) Crosshead Speed ( Inches / min ) or Rate Extension or Position Measured by XHD_100 ( XHD100 ) 10.0 By : Date : Project Tower Rd. at Pena Blvd. Classification Sandy lean clay, A-6(8) Operator LMCamsky Project Number G Boring # P-14 & P-15 Combined Depth 1-5 feet Sample Number Specific Gravity Figure 19 Remolded at 95% MDD and 2% over O Template No 216 GEOCAL 11-Oct-16 GEOCAL 7290 S. Fraser St. Centennial, CO Tel FAX

52 BEARING RATIO TEST REPORT ASTM D blows 30 blows 80 CBR (%) 1 Penetration Resistance (psi) blows Molded Density (pcf) Swell (%) Penetration Depth (in.) Elapsed Time (hrs) Density (pcf) lean clay with sand Molded Percent of Max. Dens. Moisture (%) Density (pcf) Material Description Soaked Percent of Max. Dens. Moisture (%) USCS CL CBR (%) 0.10 in in. Max. Dens. (pcf) Linearity Correction (in.) Optimum Moisture (%) Surcharge (lbs.) LL Max. Swell (%) PI Project No: G Project: Tower & Pena Blvd Ramps Location: Borings P11 & P12 combined Sample Number: Depth: 1-5 feet Date: BEARING RATIO TEST REPORT GEOCAL, INC. Test Description/Remarks: Figure 20

53 Project #: G TABLE 1 SUMMARY OF LABORATORY TEST RESULTS Client: Core Consulting Project Name: Tower Road at Pena Blvd. Sample Location Unconfined Gradation Atterberg Limits Natural Natural Swell Swell (%) Compressive AASHTO Moisture Dry Passing Liquid Plasticity Pressure (with 0.2, Strength Class. Soil or Bedrock Boring Depth Content Density Gravel Sand No. 200 Limit Index 0.5 or 1 ksf (Remolded) (Group Description No. (feet) (%) (pcf) (%) (%) Sieve (%) (%) (%) (psf) Surcharge) (psf) Index) B A-6(12) Lean clay with sand B , (1.0) Claystone bedrock B Sandy clay B A-6(9) Sandy lean clay B , (1.0) Claystone bedrock I , (0.2) A-6(3) Silty sand, fill I Sandy lean clay I Claystone bedrock P (0.2) A-7-6(36) Fat clay, fill P-1 4b (0.5) A-7-6(29) Fat clay, fill P-2 1 Lean clay P (0.5) A-6(12) Sandy lean clay, fill P Lean clay, fill P ,388 A-7-6(15) Standard Proctor AASHTO T99, Method A: MDD = pcf; OM = 18.3%. Lean clay with sand, fill P A-6(8) Sandy lean clay P (0.5) A-7-6(22) Sandy fat clay P , (0.2) A-6(8) Sandy lean clay P Clayey sand with gravel, fill P Sandy lean clay, fill P A-6(3) Clayey sand, fill P A-6(4) Sandy lean clay P , (0.2) A-6(14) Lean clay with sand P , (0.2) A-7-6(21) Fat clay with sand P A-2-6(0) Clayey sand, fill P A-6(7) Sandy lean clay P A-6(4) Clayey sand P-11 & P Standard Proctor AASHTO T99, Method A: MDD = pcf; OM = 18.6%. Combined CBR ASTM 0.10 inch 85%=0.6; 90%=1.6; 95%= inch 85%=0.7 ;90%=1.5 ;95%=1.8 P-14 & P , Combined Standard Proctor AASHTO T99, Method A: MDD = pcf; OM = 14.3%. A-7-6(16) A-6(8) Lean clay with sand Sandy lean clay

54 TABLE 2 Client: Core Consulting Project #: G SUMMARY OF LABORATORY CHEMICAL TEST RESULTS Project Name: Tower Road at Pena Blvd. Sample Location Water Laboratory Chloride AASHTO Soluble Resistivity ph Water Class. Soil or Bedrock Boring Depth Sulfates Soluble (Group Description No. (feet) ( % ) (ohm-cm) (%) Index) B Claystone bedrock B Sandy clay I Sandy lean clay I-1 9 Not Detected Claystone bedrock P Claystone bedrock P Sandy lean clay, fill P-11 4 Not Detected A-6-(14) Lean clay with sand

55 APPENDIX A MGPEC PAVEMENT DESIGN SOFTWARE PRINTOUT MGPEC FORM #9

56

57 Agency: Date: Project Number: Project Name: MGPEC Form # 9 (1/26/2012) Mixture Design Requirements for Hot Mix Asphalt Pavements (HMA) Project Special Provision Sheet for Hot Mix Asphalt Pavements (HMA) This MGPEC Form #9 is a mandatory part of the bid documents, and shall be filled out by the AGENCY for each mix specified. The Contractor shall include a copy of this form with each Mix Design submittal after the contract is awarded. Street Classification: (examples: Residential, Collector, Arterial, Industrial, Parking Lot or actual name for Project) Construction Application: Top Lift Intermediate Lift(s) Bottom Lift Patching Other Aggregate Gradation: Grading ST (1.5 or less lifts, 3/8 NMPS) Grading SX (2.5 or less lifts) Grading S (2.5+ to 3.5 lifts) Grading SG* 1 (3.5 or thicker lifts) SMA (Top lift only) 3/8 ½ ¾ * 1 Note = Grading SG depends on approved texture of mix, Grading SG lower lift(s) only. RAP Quantity, Maximum: 0% 20% 25% Notes: - A quality control plan for RAP will be required when RAP is used - Top lift Maximum RAP content allowed is 20% Superpave Gyratory Mix Design Compaction Level, Recommended usage and Recommend binder(s): Design Level Recommended Traffic Levels Recommended PG Binder(s) N design =50 Low volume PG or PG N design =75 0 to <3 million ESALs PG or PG N design =100 3 million to <30 million ESALs PG or PG Notes: - The binders are shown in order they should be considered. - Polymer modified PG Binders are typically used in the top lift only - PG Binder recommended for residential developments with less than 2 million ESAL s Target job Mix Optimum Asphalt Content Selection, Choose target % as close to 4.0 as possible (3.5% to 4.5% air voids per MGPEC 2008) Target Job Mix optimum Binder content for SMA grading at 3.0% to 4.0% air voids **Warm mix asphalt (WMA) is allowed as an alternate to hot mix asphalt provided that all material requirements and specification standards are met and as approved by the Agency. A completed MGPEC Form #9 shall supplement the MGPEC Construction Specifications defining the contract specific requirements of Item 9: Hot Mix Asphalt Pavement (HMA). Refer to the Specifications for details. MGPEC Form # ) to be used with: MGPEC Pavement Design Standards and Construction Specifications - Project Special Provisions for Hot Mix Asphalt Pavements (HMA) Item 9 Mixture Design and Production Requirements

58 Agency: Date: Project Number: Project Name: MGPEC Form # 9 (1/26/2012) Mixture Design Requirements for Hot Mix Asphalt Pavements (HMA) Project Special Provision Sheet for Hot Mix Asphalt Pavements (HMA) This MGPEC Form #9 is a mandatory part of the bid documents, and shall be filled out by the AGENCY for each mix specified. The Contractor shall include a copy of this form with each Mix Design submittal after the contract is awarded. Street Classification: (examples: Residential, Collector, Arterial, Industrial, Parking Lot or actual name for Project) Construction Application: Top Lift Intermediate Lift(s) Bottom Lift Patching Other Aggregate Gradation: Grading ST (1.5 or less lifts, 3/8 NMPS) Grading SX (2.5 or less lifts) Grading S (2.5+ to 3.5 lifts) Grading SG* 1 (3.5 or thicker lifts) SMA (Top lift only) 3/8 ½ ¾ * 1 Note = Grading SG depends on approved texture of mix, Grading SG lower lift(s) only. RAP Quantity, Maximum: 0% 20% 25% Notes: - A quality control plan for RAP will be required when RAP is used - Top lift Maximum RAP content allowed is 20% Superpave Gyratory Mix Design Compaction Level, Recommended usage and Recommend binder(s): Design Level Recommended Traffic Levels Recommended PG Binder(s) N design =50 Low volume PG or PG N design =75 0 to <3 million ESALs PG or PG N design =100 3 million to <30 million ESALs PG or PG Notes: - The binders are shown in order they should be considered. - Polymer modified PG Binders are typically used in the top lift only - PG Binder recommended for residential developments with less than 2 million ESAL s Target job Mix Optimum Asphalt Content Selection, Choose target % as close to 4.0 as possible (3.5% to 4.5% air voids per MGPEC 2008) Target Job Mix optimum Binder content for SMA grading at 3.0% to 4.0% air voids **Warm mix asphalt (WMA) is allowed as an alternate to hot mix asphalt provided that all material requirements and specification standards are met and as approved by the Agency. A completed MGPEC Form #9 shall supplement the MGPEC Construction Specifications defining the contract specific requirements of Item 9: Hot Mix Asphalt Pavement (HMA). Refer to the Specifications for details. MGPEC Form # ) to be used with: MGPEC Pavement Design Standards and Construction Specifications - Project Special Provisions for Hot Mix Asphalt Pavements (HMA) Item 9 Mixture Design and Production Requirements

59 APPENDIX B AASHTO PAVEMENT DESIGN SOFTWARE PRINTOUTS

60 Rigid Pavement Design - Based on AASHTO Supplemental Guide Reference: LTPP DATA ANALYSIS - Phase I: Validation of Guidelines for k-value Selection and Concrete Pavement Performance Prediction I. General Agency: Geocal, Inc. Street Address: 7290 S. Fraser St. City: Centennial State: Colorado, Project Number: G ID: k=45 Exit Ramp Description: Pena Blvd. Exit Ramp Location: Commerce City, Colorado II. Design Serviceability Initial Serviceability, P1: 4.5 Joint Spacing: Terminal Serviceability, P2: ft PCC Properties 28-day Mean Modulus of Rupture, (S' c )': 650 psi JPCP Elastic Modulus of Slab, E c : 3,400,000 psi Poisson's Ratio for Concrete, m: 0.15 Effective Joint Spacing: 180 in Base Properties Elastic Modulus of Base, E b : 15,000 psi Design Thickness of Base, H b : 6.0 in Slab-Base Friction Factor, f: 1.4 Reliability and Standard Deviation Reliability Level (R): 90.0 % Edge Support Factor: 0.94 Overall Standard Deviation, S 0 : 0.34 Climatic Properties Slab Thickness used for Mean Annual Wind Speed, WIND: 8.8 mph Sensitivity Analysis: 9.55 in Mean Annual Air Temperature, TEMP: 50.3 o F Mean Annual Precipitation, PRECIP: 15.3 in Subgrade k-value Design ESALs 45 psi/in 8.8 million Calculated Slab Thickness for Above Inputs: 9.55 in

61 Faulting DOWELED PAVEMENT NONDOWELED PAVEMENT Dowel Diameter: K d : E s : 1.50 in 1,500,000 psi/in 29,000,000 psi Base/Slab Frictional Restraint Stabilized Base Aggregate Base or LCB w/ bond breaker ALPHA: / o F TRANGE: o F Days90: 56 days e: strain D: 9.55 in D: 9.55 in P: 9,000 lbf T: 0.45 Base Type Stabilized Base Unstabilized Base Base Type Stabilized Base Unstabilized Base FI: 660 o F-days FI: 477 o F-days CESAL: 8.80 million CESAL: 8.80 million Age: 22.0 years Age: 20.0 years C d : 1.05 C d : 1.00 Faulting (doweled) Faulting (nondoweled) 0.04 in in Faulting Check - PASS Faulting Check - Recommended critical mean joint faulting levels for design (Table 28) Joint Spacing Critical Mean Joint Faulting < 25 ft 0.06 in > 25 ft 0.13 in

62 Rigid Pavement Design - Based on AASHTO Supplemental Guide Reference: LTPP DATA ANALYSIS - Phase I: Validation of Guidelines for k-value Selection and Concrete Pavement Performance Prediction I. General Agency: Geocal, Inc. Street Address: 7290 S. Fraser St. City: Centennial State: Colorado, Project Number: G ID: k=200 Exit Ramp Description: Pena Blvd. Exit Ramp Location: Commerce City, Colorado II. Design Pavement Type, Joint Spacing (L) Serviceability JPCP Initial Serviceability, P1: 4.5 Joint Spacing: Terminal Serviceability, P2: 2.5 JRCP 15.0 ft PCC Properties CRCP 28-day Mean Modulus of Rupture, (S' c )': 650 psi JPCP Elastic Modulus of Slab, E c : 3,400,000 psi Poisson's Ratio for Concrete, m: 0.15 Effective Joint Spacing: 180 in Base Properties Elastic Modulus of Base, E b : 15,000 psi Design Thickness of Base, H b : 6.0 in Slab-Base Friction Factor, f: 1.4 Reliability and Standard Deviation Edge Support Conventional 12-ft wide traffic lane Conventional 12-ft wide traffic lane + tied PCC 2-ft widened slab w/conventional 12-ft traffic lane Reliability Level (R): 90.0 % Edge Support Factor: 0.94 Overall Standard Deviation, S 0 : 0.34 Sensitivity Analysis Climatic Properties Slab Thickness used for Mean Annual Wind Speed, WIND: 8.8 mph Sensitivity Analysis: 8.97 in Mean Annual Air Temperature, TEMP: 50.3 o F Mean Annual Precipitation, PRECIP: 15.3 in Modulus of Rupture Elastic Modulus (Slab) Subgrade k-value Elastic Modulus (Base) Base Thickness Design ESALs 200 psi/in k-value Joint Spacing 8.8 million Reliability Standard Deviation Calculated Slab Thickness for Above Inputs: 8.97 in

63 Faulting DOWELED PAVEMENT NONDOWELED PAVEMENT Dowel Diameter: K d : E s : 1.50 in 1,500,000 psi/in 29,000,000 psi Base/Slab Frictional Restraint Stabilized Base Aggregate Base or LCB w/ bond breaker ALPHA: / o F TRANGE: o F Days90: 56 days e: strain D: 8.97 in D: 8.97 in P: 9,000 lbf T: 0.45 Base Type Stabilized Base Unstabilized Base Base Type Stabilized Base Unstabilized Base FI: 660 o F-days FI: 477 o F-days CESAL: 8.80 million CESAL: 8.80 million Age: 22.0 years Age: 20.0 years C d : 1.05 C d : 1.00 Faulting (doweled) Faulting (nondoweled) 0.05 in in Faulting Check - PASS Faulting Check - Recommended critical mean joint faulting levels for design (Table 28) Joint Spacing Critical Mean Joint Faulting < 25 ft 0.06 in > 25 ft 0.13 in

64 Rigid Pavement Design - Based on AASHTO Supplemental Guide Reference: LTPP DATA ANALYSIS - Phase I: Validation of Guidelines for k-value Selection and Concrete Pavement Performance Prediction I. General Agency: Geocal, Inc. Street Address: 7290 S. Fraser St. City: Centennial State: Colorado, Project Number: G ID: k=45 Entry Ramp Description: Pena Blvd. Entry Ramp Location: Commerce City, Colorado II. Design Pavement Type, Joint Spacing (L) Serviceability JPCP Initial Serviceability, P1: 4.5 Joint Spacing: Terminal Serviceability, P2: 2.5 JRCP 15.0 ft PCC Properties CRCP 28-day Mean Modulus of Rupture, (S' c )': 650 psi JPCP Elastic Modulus of Slab, E c : 3,400,000 psi Poisson's Ratio for Concrete, m: 0.15 Effective Joint Spacing: 180 in Base Properties Elastic Modulus of Base, E b : 15,000 psi Design Thickness of Base, H b : 6.0 in Slab-Base Friction Factor, f: 1.4 Reliability and Standard Deviation Edge Support Conventional 12-ft wide traffic lane Conventional 12-ft wide traffic lane + tied PCC 2-ft widened slab w/conventional 12-ft traffic lane Reliability Level (R): 90.0 % Edge Support Factor: 0.94 Overall Standard Deviation, S 0 : 0.34 Sensitivity Analysis Climatic Properties Slab Thickness used for Mean Annual Wind Speed, WIND: 8.8 mph Sensitivity Analysis: in Mean Annual Air Temperature, TEMP: 50.3 o F Mean Annual Precipitation, PRECIP: 15.3 in Modulus of Rupture Elastic Modulus (Slab) Subgrade k-value Elastic Modulus (Base) Base Thickness Design ESALs 45 psi/in k-value Joint Spacing 16.8 million Reliability Standard Deviation Calculated Slab Thickness for Above Inputs: in

65 Faulting DOWELED PAVEMENT NONDOWELED PAVEMENT Dowel Diameter: K d : E s : 1.50 in 1,500,000 psi/in 29,000,000 psi Base/Slab Frictional Restraint Stabilized Base Aggregate Base or LCB w/ bond breaker ALPHA: / o F TRANGE: o F Days90: 56 days e: strain D: in D: in P: 9,000 lbf T: 0.45 Base Type Stabilized Base Unstabilized Base Base Type Stabilized Base Unstabilized Base FI: 660 o F-days FI: 477 o F-days CESAL: million CESAL: million Age: 22.0 years Age: 20.0 years C d : 1.05 C d : 1.00 Faulting (doweled) Faulting (nondoweled) 0.05 in in Faulting Check - PASS Faulting Check - Recommended critical mean joint faulting levels for design (Table 28) Joint Spacing Critical Mean Joint Faulting < 25 ft 0.06 in > 25 ft 0.13 in

66 Rigid Pavement Design - Based on AASHTO Supplemental Guide Reference: LTPP DATA ANALYSIS - Phase I: Validation of Guidelines for k-value Selection and Concrete Pavement Performance Prediction I. General Agency: Geocal, Inc. Street Address: 7290 S. Fraser St. City: Centennial State: Colorado, Project Number: G ID: k=200 Entry Ramp Description: Pena Blvd. Entry Ramp Location: Commerce City, Colorado II. Design Pavement Type, Joint Spacing (L) Serviceability JPCP Initial Serviceability, P1: 4.5 Joint Spacing: Terminal Serviceability, P2: 2.5 JRCP 15.0 ft PCC Properties CRCP 28-day Mean Modulus of Rupture, (S' c )': 650 psi JPCP Elastic Modulus of Slab, E c : 3,400,000 psi Poisson's Ratio for Concrete, m: 0.15 Effective Joint Spacing: 180 in Base Properties Elastic Modulus of Base, E b : 15,000 psi Design Thickness of Base, H b : 6.0 in Slab-Base Friction Factor, f: 1.4 Reliability and Standard Deviation Edge Support Conventional 12-ft wide traffic lane Conventional 12-ft wide traffic lane + tied PCC 2-ft widened slab w/conventional 12-ft traffic lane Reliability Level (R): 90.0 % Edge Support Factor: 0.94 Overall Standard Deviation, S 0 : 0.34 Sensitivity Analysis Climatic Properties Slab Thickness used for Mean Annual Wind Speed, WIND: 8.8 mph Sensitivity Analysis: in Mean Annual Air Temperature, TEMP: 50.3 o F Mean Annual Precipitation, PRECIP: 15.3 in Modulus of Rupture Elastic Modulus (Slab) Subgrade k-value Elastic Modulus (Base) Base Thickness Design ESALs 200 psi/in k-value Joint Spacing 16.8 million Reliability Standard Deviation Calculated Slab Thickness for Above Inputs: in