Geotechnical Engineering Report

Transcription

1 Geotechnical Engineering Report Sterling Site Office Building Commerce Street San Antonio, Texas Prepared for: Jasmine Engineering San Antonio, Texas Prepared by: TTL/Drash Consultants, LLC San Antonio, Texas June 9, 2017

2 June 9, 2017 Ms. Jasmine Azima, PE Jasmine Engineering 115 East Travis, Suite 1020 San Antonio, Texas O: (210) E: SUBJECT: Geotechnical Engineering Report Sterling Site Office Building Commerce Street San Antonio, Texas Dear Ms. Azima: TTL/Drash Consultants, LLC (TTL/Drash) is pleased to submit this geotechnical engineering report (Report) for the above referenced Project. If you have any questions regarding our Report, or if additional services are needed, please do not hesitate to contact us. We appreciate the opportunity to work with you. Respectfully Submitted, TTL/Drash Consultants Chester J. Drash, PE Senior Principal CJD/set 116E Copies To: Addressee: (1) Bound & (1) Electronic 1045 Central Parkway North, Suite 103 San Antonio, Texas P: F: TBPE Firm Registration No. F TBPG Firm Registration No Geotechnical Construction Materials Environmental Forensics

3 TABLE OF CONTENTS Page EXECUTIVE SUMMARY... i INTRODUCTION... 1 Purpose and Scope of Services... 1 PROJECT INFORMATION... 1 SITE AND SUBSURFACE CONDITIONS... 2 Site Conditions... 2 Subsurface Conditions... 2 Subsurface Stratigraphy... 2 Subsurface Water... 2 GEOTECHNICAL RECOMMENDATIONS AND GUIDELINES... 3 Slab Foundation... 4 Slab Design Criteria... 4 Slab Design Notes... 4 Construction Considerations... 5 Seismic Design Considerations... 5 Landscape Design... 5 Drainage Adjacent to Structures... 6 Utility Trenches... 6 Earthwork... 7 General Site Preparation... 8 Building Pad Preparation... 8 Fill Materials and Placement... 9 Pavements Pavement Section Materials...11 Pavement Joints, Reinforcement, and Dowels...13 INTERPRETATION OF REPORT CONSTRUCTION MONITORING AND TESTING LIMITATIONS OF REPORT EXHIBITS Exhibit 1 Site Boring Location Plan Exhibits 2 to 5 Logs of Borings APPENDIX FIELD AND LABORATORY Exploratory Drilling Program Laboratory Testing Program Notes Regarding Soil and Rock

4 EXECUTIVE SUMMARY This geotechnical engineering report (Report) has been prepared for the design and construction of a new single-story office building (Project). The Project is located at the southwest corner of Commerce Street and South Hackberry in San Antonio, Texas. The single-story office building will be either a concrete tilt-wall panel or CMU (concrete masonry unit) frame structure with interior steel columns. The office building will be supported on a slab-on-grade foundation system. Surface parking is planned for tenants and visitors. Based on the information provided to us for this study by the design team members and from data developed as part of our engineering service, the site is suitable for the planned improvements. A general summary of our findings, conclusions, and recommendations with regards to the geotechnical engineering aspects of the Project are provided below: Subsurface soil conditions generally consist of a surficial dark brown, brown, and light brown FAT clay soil layer, which is underlain by a gravelly zone that is present from about 8 to 10 feet. Underlying this gravelly zone is a tan and gray FAT clay. Key design information is as follows: o o o o The subsurface stratigraphy exhibits a high potential for volume changes (expansion and contraction) with fluctuations in its moisture content. The subsoils, in their current state, yield a Potential Vertical Rise (PVR) in the range of about 2 to 5 inches. To reduce the PVR beneath the building footprint, an engineered building pad will be required to reduce the PVR to 1-inch, which was requested by the Project Structural Engineer. A slab-on-grade foundation will be used to support the structure. Foundation beams shall bear at least 18 inches below final exterior grade in the compacted building pad fill material. Foundation beams may be sized for a net allowable total load bearing pressure of 3,000 psf or net allowable dead plus gravity live load bearing pressure of 2,000 psf. The estimated settlement beneath the foundation beams, provided proper and quality construction is performed, is estimated to be less than 1-inch. Pavement recommendations are provided for both asphalt and concrete sections. This summary is provided for convenience only. For those individuals and entities that may need more details or technical information from this Report for their use, it must be read in its entirety to have an understanding of the information and recommendations provided for the Project. Sterling Site Office Building i

5 GEOTECHNICAL ENGINEERING REPORT STERLING SITE OFFICE BUILDING COMMERCE STREET SAN ANTONIO, TEXAS INTRODUCTION This geotechnical engineering report (Report) has been prepared for the design and construction of a new single-story office building (Project). The Project is located at the southwest corner of Commerce Street and South Hackberry in San Antonio, Texas. Purpose and Scope of Services The purposes of this engineering service were to evaluate the general subsurface conditions (soil, rock, subsurface water) within the Project limits by drilling exploratory borings, conduct tests on samples recovered during drilling of the exploratory borings, analyze and evaluate the test data, perform engineering analyses using the data analyzed and evaluated from the field and laboratory programs to develop geotechnical engineering recommendations and guidelines with respect to: Site conditions as applicable; Earthwork as applicable; Subsurface stratigraphy; Foundation design and construction; Subsurface water conditions; Estimate of foundation movement; and Potential for soil expansion-contraction; Pavement recommendations. PROJECT INFORMATION The following information was provided to us by the Client, design professionals working on the Project, or was collected by our firm: Project Location Project The planned site is located at the southwest corner of Commerce Street and South Hackberry in San Antonio, Texas. The Project will involve the design and construction of a new single-story office building with associated parking areas. The single-story office building will be either a CMU (concrete masonry walls) or concrete tilt-wall panel frame structure with interior steel columns. The roof will be supported on steel joists that will be supported by interior steel columns and the exterior walls. The single-story office building is expected to have a footprint of about 7,000 square feet. The single-story office building will be supported on a slab-onground foundation system that will be supported on an engineered fill pad. Sterling Site Office Building 1

6 Current Site Conditions Current Topography Proposed Topography The Project site is currently occupied by a residential structure and two commercial buildings. The remaining portions of the site are covered with grass, weeds, and a few trees, Final site grading plans were not available to us at the time that this Report was submitted. Based on visual observations, the Site is relatively level. Based on information provided to us by the Project design team, we understand that the proposed Finished Floor Elevation (FFE) of the office building is set at about 6 to 12 inches above existing sidewalk elevation. If this information changes, TTL/Drash shall be contacted to reevaluate or revise our recommendations accordingly. SITE AND SUBSURFACE CONDITIONS Site Conditions The site, as noted previously, is currently occupied by residential and commercial structures, covered with grass and weeds, and contains a few trees. Based on visual observations, there were no noticeable or obvious conditions within the site that would affect the geotechnical engineering aspects of this Project. Subsurface Conditions Subsurface conditions within the Project limits were evaluated by drilling exploratory borings at the locations shown on Exhibit 1, Site Boring Location Plan. Information retrieved from the exploratory borings is summarized herein. Subsurface Stratigraphy Subsurface stratigraphy, based on the exploratory borings, generally consists of a surficial dark brown, brown, and light brown FAT clay soil layer, which is underlain by a gravelly zone that is present from about 8 to 10 feet. Underlying this gravelly zone is a tan and gray FAT clay. Please note that a hydrocarbon ( fuel ) odor was observed during drilling and sampling of exploratory boring B-1. Additional soil sampling was performed, including the installation of vapor wells, as a follow up to the observing the hydrocarbon odor. Soil samples were also field screened utilizing a photo-ionization detector (PID). Information regarding the presence of hydrocarbon odor is provided in a separate report (TTL/Drash No. 116E The logs of borings, presenting more specific information about the subsurface stratigraphy encountered at each exploratory boring location, are provided in the Exhibits section of this Report. Subsurface Water Subsurface water was not encountered during drilling or upon completion of the exploratory borings below existing ground surface (ground surface at the time of our field activities). Each exploratory boring was then backfilled with the spoils generated during our drilling operations. Even though subsurface water was not detected during drilling, the gravelly zone that is present from about 8 to 10 feet is a conduit for subsurface water to flow. As noted in the following paragraph, subsurface water can develop during changes in seasonal and climatic conditions. Sterling Site Office Building 2

7 Subsurface water is generally encountered as a true or permanent water source or as a perched or temporary water source. Permanent subsurface water is generally present year round, which may or may not be influenced by seasonal and climatic changes. Temporary subsurface water generally develops as a result of seasonal and climatic conditions. The construction activities can also interrupt surface and subsurface water flow, which can cause variations in subsurface water levels and changes in surface water flow patterns. Based on the planned development and our exploratory soil borings, subsurface water is not expected to affect or impact the planned building design or construction activities. However, we do recommend that the subsurface water conditions be rechecked by the contractor or applicable subcontractors before conducting any site excavations. GEOTECHNICAL RECOMMENDATIONS AND GUIDELINES Based on the information provided to us by the Client and Project Team, our exploratory borings drilled at the site, results of laboratory tests performed on samples recovered during the subsurface exploration program, and our engineering analyses, the following statements can be made regarding the Project site: The site is suitable for the planned construction. Based on information provided to us by the Project design team, we understand that the proposed FFE of the single-story office building is set at about 6 to 12 inches above existing sidewalk elevation. Our recommendations are based on these proposed elevations. If this information changes, TTL/Drash shall be contacted to re-evaluate or revise our recommendations accordingly. The subsurface stratigraphy exhibits a high potential for volume changes (expansion and contraction) with fluctuations in its moisture content. An engineered building pad will be required beneath the footprint of the single-story building to reduce the potential for expansion and contraction. The single-story building can be supported on a slab foundation system. Both flexible (asphalt) and rigid (concrete) pavements may be considered for the parking and driveway areas. The foundation being considered must be designed to reduce the possibility of soil failure when subjected to axial and lateral load conditions. The foundation must also be designed so that foundation movements, whether vertical, horizontal or rotational, are within allowable limits of the soil and within design and operational limits of the proposed structure. The following geotechnical recommendations and guidelines have been prepared based on the data collected or developed during this Project, our experience with similar projects, and our knowledge of sites with similar surface and subsurface conditions. Sterling Site Office Building 3

8 Slab Foundation Slab Design Criteria Parameters for design of the grade supported slab foundation are presented herein. The slab foundation recommendations assume that the building pad for the single-story office building will be prepared as discussed in the Earthwork section of this Report. Design parameters are provided below for the appropriate slab design method. Slab Design Notes CRSI (Concrete Reinforcing Steel Institute) Method 1, 2, 3, 4, 7 Net Allowable Bearing Pressures 6 Total Load Conditions (psf): 3000 Dead Load Plus Gravity Live Load Conditions (psf): 2000 Maximum Allowable Deflection Ratio of Beam Footing: 1/360 Subgrade Modulus, k (pci): See table below WRI (Wire Reinforcement Institute) Method 1, 2, 3, 4, 7 Design Plasticity Index 5 : 28 Climatic Rating (C w ): 16 Soil Climate Support Index (1-C): 0.86 Site Slope (%): 0 Soil Unconfined Compressive Strength, q u (tsf): 1.0 Net Allowable Bearing Pressures 6 : Total Load Conditions (psf): 3000 Dead Load Plus Gravity Live Load Conditions(psf): 2000 Maximum Allowable Deflection Ratio of Foundation Beam: 1/360 The following notes apply to the slab design methods presented in the previous subsection. 1 Design parameters are based on preparing the subgrade and constructing a building pad as recommended in the Earthwork section of this Report. 2 This is essentially an empirical design method and the recommended design parameters are based on our understanding of the proposed Project, our interpretation of the information and data collected as a part of this study, our area experience, and the criteria published in the WRI and CRSI design manuals. 3 The width of the foundation beams shall not be less than 12 inches. The foundation beam bearing depth shall be at least 18 inches below final exterior grade; foundation beams will terminate in compacted fill. At concentrated column loads, the foundation beam may be thickened or widened to carry the applied load. These foundation dimension recommendations are for proper development of bearing capacity for the foundation beams and to reduce the potential for water to migrate beneath the slab foundation system. These recommendations are not based on structural considerations of the applicable design method. Actual foundation depths and widths may need to be greater than the minimum recommended herein for structural considerations, which should be properly evaluated and designed by the Structural Engineer. 4 If the floor slab of the foundation is to be covered with wood, vinyl tile, carpet, or other moisture sensitive or impervious coverings, a vapor barrier shall be placed beneath slab foundations, including the foundation beams. The designer should be familiar with the American Concrete Institute (ACI) 302 for procedures and cautions about the use and placement of a vapor barrier. 5 Based on the weighted average method for a depth of 15 feet. Sterling Site Office Building 4

9 6 Includes a factor of safety (FS) of at least 2 for total load conditions and at least 3 for dead load plus gravity live load conditions. 7 The estimated settlement beneath the foundation beams, provided proper and quality construction is performed, should be less than 1-inch. Construction Considerations Excavations for the foundation beams shall be neat excavated with a smooth-mouthed bucket. If a toothed bucket is used, excavation with this bucket shall be stopped 6 inches above the final foundation beam bearing elevation and the foundation beam excavation completed with a smooth-mouthed bucket or by hand labor. Debris in the bottom of the foundation beam excavation shall be removed prior to steel placement. If neat excavation is not possible then the foundation beam shall be overexcavated and formed. All loose materials shall be removed from the overexcavated areas and filled with lean concrete or compacted cement stabilized sand (two sacks cement to one cubic yard of sand). The foundation beam excavations shall be sloped sufficiently to create internal sumps for runoff collection and removal of water. If surface runoff water or subsurface water seepage in excess of 1-inch accumulates at the bottom of the foundation beam excavation, it shall be collected and removed so that the ponding water does not adversely affect the quality of the foundation beam bearing surface. Special attention shall be given to protect the exposed foundation beam bearing soils from being disturbed or drying out prior to placement of the reinforcing steel and concrete. Seismic Design Considerations Presented below are the seismic design criteria for the Project site and immediate area. Description Value 2015 International Building Code Site Classification (IBC) 1 C 2 Site Latitude Site Longitude Maximum Considered Earthquake 0.2 second Design Spectral Response Acceleration (S DS) Maximum Considered Earthquake 1.0 second Design Spectral Response Acceleration (S D1) The site class definition was determined using SPT N-values in conjunction with Table in the 2015 IBC. The Spectral Acceleration values were determined using publicly available information provided on the United States Geological Survey (USGS) website. The above criteria can be used to determine the Seismic Design Category using Tables (1) and (2) in the 2015 IBC. 2 Note: The 2015 IBC requires a site soil profile determination extending to a depth of 100 feet for seismic site classification. The current scope does not include the required 100-foot soil profile determination. The boring(s) extended to a maximum depth of 20 feet, and this seismic site class definition considers that hard soil continues below the maximum depth of the subsurface exploration. Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration. Landscape Design We realize that landscaping is vital to the aesthetics of any project. The Project Owner and Project Design Team, particularly the Architect and Landscape Architect, should be made aware that placing large bushes and trees adjacent to the structure may contribute to future distress to Sterling Site Office Building 5

10 the foundation system and structure. Vegetation placed in landscape beds that are adjacent to the structure should be limited to small plants and shrubs that will not exceed a mature height of about 4 feet and that are not water demanding. Large bushes and trees that will generally exceed 4-foot heights should be planted at a distance away from the structure so that their canopy or drip line does not extend to the structure s perimeter when the tree reaches maturity. Plants and shrubs that are water hungry should not be planted within 5 feet of the structure. Watering of vegetation, particularly landscape beds adjacent to the structure shall be performed in a timely and controlled manner. Excessive watering, as well as no consistent watering, shall be avoided. Drainage Adjacent to Structures The performance of the foundation system for the proposed structures will not only be dependent upon the quality of construction, but also upon the stability of the moisture content of the soils underlying the foundation. The Project Civil Engineer should design final site grades so that there is positive surface drainage away from the structures. Post-construction accumulation or ponding of surface runoff near structures must be avoided. Utility Trenches Various utilities will be installed at the Site. The utilities may include sanitary sewer lines, storm drainage (i.e., sewer lines, concrete drainage channels, culverts, etc.), electrical lines, gas lines, and telecommunication lines. Installation of these utilities should conform to the applicable specifications of the utility entities as follows: Sanitary Sewer and Water Lines o o San Antonio Water System ( SAWS ) 2008 Specifications for Water and Sanitary Sewer Construction; latest revision. City of San Antonio ( COSA ) Grading and Clearing Ordinance 94002; as amended. Storm Water Sewer Lines and Storm Drainage o o COSA 2008 Standard Specifications for Construction; latest revision. COSA Grading and Clearing Ordinance 94002; as amended. Electrical and Gas Lines o o o City Public Service ( CPS Energy ) Electrical Service Standards; latest edition. CPS Energy Gas Service Standards; latest edition. COSA Grading and Clearing Ordinance 94002; as amended. Utilities not referenced above, such as telecommunications, small water lines, or sanitary sewer laterals, should meet the following minimum installation guidelines. The bottom of the utility trench excavation should be clean of loose soils and debris prior to placement of the utility pipe or cable. Sterling Site Office Building 6

11 Backfill above the utility pipe or cable should be as follows: o o Earthwork Traversing Non-Pavement or Non-Load Bearing Areas: The backfill soils may be the excavated soils. Place the backfill soils in loose lifts not to exceed 8 inches in thickness to achieve compaction thickness no greater than 6 inches. Add water as applicable so that the soil moisture content after compaction is between minus 2 and plus 3 percent of the optimum moisture content. Compact each backfill soil lift to at least 95 percent of standard moisturedensity relationship (ASTM D 698). Traversing Pavement or Load Bearing Areas (select one of the following): Place 12 inches of backfill soils, which may be the excavated soils, above the utility pipe or cable: OR, Place the backfill soils in loose lifts not to exceed 8 inches in thickness to achieve compaction thickness no greater than 6 inches. Add water as applicable so that the soil moisture content after compaction is between minus 2 and plus 3 percent of the optimum moisture content. Compact the backfill soil lift to at least 95 percent of standard moisture-density relationship (ASTM D 698). Place flowable fill in the utility trench, terminating at a depth to accommodate the applicable pavement section or slab. The flowable fill shall have a 28-day compressive strength between 25 and 100 psi. Recommendations and guidelines for general site preparation, building pad preparation, and placement of fill soils at the Project site are discussed in this section. The recommendations presented for design and construction of earth supported elements including foundations and floor slabs are contingent upon following the recommendations and guidelines outlined in this section. Earthwork on the Project shall be evaluated by our firm. The evaluation of earthwork shall include observation and testing of all fill soils placed at the site, subgrade preparation beneath buildings and pavements, and any load-bearing requirements within the Project. The contractor or its applicable subcontractor(s) are responsible for designing and constructing stable, temporary excavations, as required to maintain stability of both the excavation sides and bottom. Excavations shall be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. Sterling Site Office Building 7

12 General Site Preparation Construction operations may encounter difficulties with wet or soft surface soils becoming a general hindrance to equipment due to rutting and pumping of the soil surface, especially during and soon after periods of wet weather. If the subgrade cannot be adequately compacted to minimum densities as described in the Fill Materials and Placement section of this Report, one of the following measures may be required: Removal and replacement with base material. Drying by natural means if the schedule allows. TTL/Drash should be contacted for additional recommendations, if soil support during construction is needed. Building Pad Preparation Based on information provided to us by the Project design team, we understand that the proposed FFE of the single-story office building is set to be about 6 inches to 12 inches higher than the existing sidewalk elevation. Our building pad recommendations are based on the proposed FFE. If this information changes, TTL/Drash shall be contacted to re-evaluate or revise our recommendations accordingly. To achieve a potential vertical rise (PVR) that is 1-inch, which was requested by the Project Structural Engineer and to design the slab foundation system for this PVR value, the building pad for the single-story office building shall be prepared as follows: Strip vegetation, loose topsoil and any otherwise unsuitable materials from the building area; this debris shall be hauled off site and properly disposed. The building area is defined as the area that extends at least 3 feet (horizontal) beyond the perimeter limits of the planned single-story office building and any adjacent flatwork. Remove the on-site soils to a depth that is at least 6½ feet below the existing sidewalk elevation along Commerce Street. Before placing any select fill for the building pad, the exposed soil excavation bottom shall be proof-rolled with at least a 20-ton roller, or equivalent equipment, to evidence any weak yielding zones. If any weak yielding zones are present, they shall be over excavated, both vertically and horizontally, to expose competent material. The excavated material can be used to restore grade provided that the material is relatively free and clean of deleterious material or materials exceeding 3 inches in maximum dimension. After proof-rolling and replacing any weak yielding zones, scarify the exposed soil excavation bottom to a depth of 6 inches, moisture condition the soils to between plus one (+1) and plus four (+4) percentage points above optimum moisture content, and compact to between 92 and 97 percent of standard compaction (ASTM D698). Sterling Site Office Building 8

13 After moisture conditioning the clay soil subgrade, select lean clay fill shall then be placed to achieve the FFE provided on the construction drawings. Specifications for a select lean clay fill is provided in the following subsection. Please note that only a select lean clay fill shall be used so that a bathtub effect is not created within the building pad matrix. Each lift of select fill shall be moisture conditioned to between minus two (-2) and plus three (+3) percentage points of optimum moisture content. To provide uniform slab support and create a more all-weather working surface, we recommend constructing the final 4 inches of the building pad with granular select fill. Each lift of granular select fill shall be moisture conditioned to between minus two (-2) and plus three (+3) percentage points of optimum moisture content. Specifications for selection and placement of granular select fill are provided in the following subsection. Fill Materials and Placement Unless noted otherwise in another section of this Report, select fill shall meet the following criteria. Specification for Fill Materials Fill Type 1 Select Fill Granular 2 Select Lean Clay Fill 3 On-Site Soils Acceptable Location for Placement Where specified in this Report. Any location. The on-site FAT clay soils are not acceptable for use as fill on this Project site. 1 Fill, whether select or non-select, that is being placed in a controlled and compacted manner shall meet one of the above specifications, be free of debris (i.e. trash, rubble, organic materials, vegetation, roots), have no particles exceeding 3 inches in maximum dimension. Prior to any filling operations, samples of the fill materials, whether select or non-select, to be used for construction shall be submitted for approval, which will include performing laboratory tests to verify compliance to the above specifications. 2 Granular Select Fill shall meet one of the following criterion: Crushed stone meeting Type A, Grades 1, 2, or 3 of the 2014 TxDOT Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges. Designation as a GC or GM in accordance with the Unified Soil Classification System (USCS). Crushed concrete meeting Type D, Grades 1, 2, or 3 of the 2014 TxDOT Standard Specifications for Construction and Maintenance of Highways, Streets, and Bridges. Designation as a GC or GM in accordance with the USCS. Commercial Grade Base (may locally be referred to as three-quarters to dust material) that is produced by some local/regional quarries having nothing retained on the 2-inch sieve, at least 60 percent retained on the No. 40 sieve, at least 80 percent retained on the No. 200 sieve, a LL no greater than 30, and a PI of 7 or less. Designation as a GM in accordance with the USCS. Sterling Site Office Building 9

14 3 Select Lean Clay Fill shall meet the following criteria: Lean clay having a PI between 12 and 20 and at least 70 percent by weight passing the No. 200 Sieve and no more than 15 percent by weight retained on the No. 4 Sieve. Designation as a CL in accordance with the USCS. Item Moisture Content and Compaction of General Fill and Backfill Moisture Content and Compaction of Select Fill and Select Backfill Moisture Content and Compaction of On-Site Soils Pavements Placement and Compaction Requirements for Fill Materials Description All general fill and backfill shall be placed in thin, loose lifts not to exceed 8 inches, with compacted thickness of about 6 inches. Unless specified elsewhere in this Report, compact to at least 95 percent of the maximum dry density as determined by the Standard effort (ASTM D 698). Each lift shall be moisture conditioned between -2 and +3 percentage points of the optimum moisture content. Unless specified elsewhere in this Report, compact to at least 95 percent of the maximum dry density as determined by the Standard effort (ASTM D 698). Each lift shall be moisture conditioned between -2 and +3 percentage points of the optimum moisture content. Unless specified elsewhere in this Report, compact to between 92 and 97 percent of the maximum dry density as determined by the Standard effort (ASTM D 698). The on-site soils shall be moisture conditioned between +1 and +4 percentage points of the optimum moisture content. Both flexible and rigid pavement systems may be considered for the Project. Based on our knowledge of the Project, we anticipate that traffic loads will be produced primarily by automobile traffic and occasional delivery and trash removal trucks. Pavement Sections. The flexible pavement section was designed in general accordance with the National Asphalt Pavement Association (NAPA) Information Series (IS-109) method (Class 1 for Light and Class 2 for Heavy). For this Project, Light and Heavy pavement section alternatives are being provided. Light is for areas expected to receive only vehicle traffic such as cars, pick-ups, and SUV s. Heavy assumes areas with heavy traffic, such as trash pickup areas and main access drive areas. If heavier traffic loading is expected, TTL/Drash shall be provided with the information and allowed to review these pavement sections. Asphalt Pavement Section On-Site Soils or Soil Fill Materials FLEXIBLE PAVEMENT SYSTEM Light Heavy Hot Mix Asphaltic Concrete 2.0 inches 2.0 inches Granular Base Material inches 12.0 inches Moisture Conditioned Raw Subgrade 6.0 inches 6.0 inches Sterling Site Office Building 10

15 1 Type B HMAC, also referred to as asphalt treated base material, may be used in place of granular base material. Every 2 inches of granular base material may be replaced with 1 inch of Type B HMAC material. However, the minimum thickness of the Type B HMAC material shall not be less than 4 inches. Concrete Pavement Section On-Site Soils or Soil Fill Materials RIGID PAVEMENT SYSTEM Light Heavy Reinforced Concrete 5.0 inches 6.0 inches Moisture Conditioned Raw Subgrade 6.0 inches 6.0 inches Proper perimeter drainage is very important and shall be provided so infiltration of surface water from unpaved areas surrounding the pavement is minimized. We do not recommend installation of landscape beds or islands in the pavement areas. Such features provide an avenue for water to enter into the pavement section and underlying soil subgrade. Water penetration usually results in degradation of the pavement section with time as vehicular traffic traverses the affected areas. Above grade planter boxes, with drainage discharge onto the top of the pavement or directed into sewers, should be considered if landscape features are desired. Also, the Asphalt Institute recommends a minimum of 2 percent slope for asphalt pavements. The importance of proper drainage cannot be overemphasized and should be thoroughly considered by the Project Team. If curbs are proposed, the curbs should extend through the base in areas where the pavement subgrade is soil; the curb should extend at least 3 inches below the base course. This will help reduce migration of subsurface water into the pavement base course from adjacent areas. A crack sealant compatible to both asphalt and concrete should be provided at all concreteasphalt interfaces. Pavement areas that will be subjected to heavy wheel and traffic volumes, such as waste bin or "dumpster" areas, entrance/exit ramps, and delivery areas, should be a rigid pavement section constructed of reinforced concrete. The concrete pavement areas should be large enough to properly accommodate the vehicular traffic and loads. For example: The dumpster pad shall be large enough so that the wheels of the collection truck are entirely supported on the concrete pavement during lifting of the waste bin; and The concrete pavement should extend beyond any areas that require extensive turning, stopping, and maneuvering. The pavement design engineer should consider these and other similar situations when planning and designing pavement areas. Waste bin and other areas that are not designed to accommodate these situations often result in localized pavement failures. Pavement Section Materials Presented below are selection and preparation guidelines for various materials that may be used to construct the pavement sections. Submittals shall be made for each pavement Sterling Site Office Building 11

16 material. The submittals should be reviewed by TTL/Drash and any appropriate members of the Project Team. The submittals should provide test information necessary to verify full compliance with the recommended or specified material properties. Hot Mix Asphaltic Concrete Surface Course - The asphaltic concrete surface course shall be plant mixed, hot laid Type C or D Surface meeting the master specifications requirements of 2014 TXDOT Standard Specifications Item 341 and specific criteria for the job mix formula. The mix shall be compacted between 91 and 95 percent of the maximum theoretical density as measured by TEX-227-F. The asphalt cement content by percent of total mixture weight shall fall within a tolerance of ±0.3 percent asphalt cement from the specific mix. In addition, the mix shall be designed so 75 to 85 percent of the voids in the mineral aggregate (VMA) are filled with asphalt cement. The grade of the asphalt cement shall be PG or higher performance grade. Aggregates known to be prone to stripping shall not be used in the hot mix. If such aggregates are used measures shall be taken to mitigate this concern. The mix shall have at least 70 percent strength retention when tested in accordance with TEX-531-C. Pavement specimens, which shall be either cores or sections of asphaltic pavement, will be tested according to Test Method TEX-207-F. The nucleardensity gauge or other methods which correlate satisfactorily with results obtained from Project pavement specimens may be used when approved by the Engineer. Asphaltic Base Course - The asphaltic base material shall meet the specification requirements of 2014 TxDOT Standard Specification Item 340, Type A or B. Prime Coat - The prime coat shall consist of sealing the base with an oil such as an MC-30 or an emulsion. The prime coat shall be applied at a rate of about 0.2 to 0.5 gallons per square yard with materials which meet TxDOT Item 300. The prime coat will help to minimize penetration of rainfall and other moisture that penetrates the base. Granular Base Material - Base material may be composed of crushed limestone base meeting all of the requirements of 2014 TxDOT Item 247, Type A, Grade 1 or 2; the material shall have no more than 15 percent of the material passing the No. 200 sieve. The base shall be compacted to at least 98 percent of the maximum dry density determined in accordance with the Standard effort (ASTM D 698) at moisture contents ranging between -2 and +3 percentage points of the optimum moisture content. Concrete - Concrete shall have a minimum 28-day design compressive strength of 4,000 psi and a design flexural strength of 650 psi. Moisture Conditioned Subgrade - The subgrade shall be scarified to a depth of 6 inches and then moisture conditioned and compacted as recommended in this Report. Sterling Site Office Building 12

17 Pavement Joints, Reinforcement, and Dowels The following is recommended for all concrete pavement sections in this Report. Refer to ACI 330 Guide for Design and Construction of Concrete Parking Lots for additional information. Contraction Joint Spacing: Contraction Joint Depth: Contraction Joint Width: Construction Joint Spacing: Construction Joint Depth/Width: Isolation Joint Spacing: Isolation Joint Depth: Isolation Joint Width: Expansion Joint: Distributed Steel: 10 feet each way. At least ¼ of pavement thickness. Shall be ¼ inch or as required by joint sealant manufacturer. To attempt to limit the quantity of joints in the pavement, consideration can be given to installing construction joints at contraction joint locations, where it is applicable. Full depth of pavement thickness. Construction sealant reservoir along one edge of the joint. Width of reservoir to be ¼ inch or as require by joint sealant manufacturer. Depth of reservoir to be at least ¼ of pavement thickness. As required to isolate pavement from structures, etc. Full depth of pavement thickness. Shall be ½ to 1 inch or as required by the joint sealant manufacturer. None (Please note that in this general area, drying shrinkage of the concrete typically significantly exceeds anticipated expansion due to thermal affects. As a result, the need for expansion joints is eliminated provided all joints (including saw cuts) are sealed. Construction of an unnecessary joint may also become a maintenance problem. All joints shall be sealed. If all joints, including sawcuts, are not sealed then expansion joints shall be installed. Steel reinforcement may consist of steel bars described as follows: No. 3 reinforcing steel bars at 12 inches on-center-each-way, Grade 60; or No. 4 reinforcing steel bars at 18 inches on-center-each-way Grade 60. All construction joints shall have dowels. Dowel information varies with pavement thickness as follows: Pavement Thickness: 5 inches 6-7 inches Dowels: 5/8 inch diameter 7/8 inch diameter Dowel Spacing: 12 inches on center 12 inches on center Dowel Length: 12 inches long 14 inches long Dowel Embedment: 5 inches 7 inches Curbs shall be dowelled to the concrete pavement section. INTERPRETATION OF REPORT TTL/Drash understands that its geotechnical engineering report is used by the Client and various individuals and firms involved with the design and construction of the Project. TTL/Drash shall be invited to attend Project meetings (in person or teleconferencing) or be contacted in writing to address applicable issues relating to the geotechnical engineering Sterling Site Office Building 13

18 aspects of the Project. TTL/Drash should also be retained to review the final construction plans and specifications to evaluate if the information and recommendations in our geotechnical engineering report has been properly interpreted and implemented in the design and specifications. CONSTRUCTION MONITORING AND TESTING The performance of the foundation system for the proposed structure will be highly dependent upon the quality of construction. As the Geotechnical Engineer of Record for this Project, TTL/Drash should be retained to provide construction observation and materials testing services during the Project, particularly the construction activities relating to foundations, building pad, pavements, excavation and site grading. LIMITATIONS OF REPORT This geotechnical engineering report is based upon the information provided to us by the Client and various other individuals and entities associated with the Project, exploratory borings drilled within the Project limits, laboratory testing of randomly selected soil or rock samples recovered during drilling of the exploratory borings, and our engineering analyses and evaluation. The Client and readers of this geotechnical engineering report, should realize that subsurface variations and anomalies can and will exist across the site and between the exploratory borings. The Client and readers should realize that site conditions will change due to the modifying effects of seasonal and climatic conditions. The nature and extent of such site or subsurface variations may not become evident until construction commences or is in progress. If site and subsurface anomalies or variations exist or develop, TTL/Drash should be contacted immediately so that the situation can be evaluated and addressed with applicable recommendations. The contractor and applicable subcontractors should familiarize themselves with this Report prior to the start of their construction activities, contact TTL/Drash for any interpretation or clarification of the Report, retain the services of their own consultants to interpret this Report, or perform additional geotechnical testing prior to bidding and construction. Unless stated otherwise in this Report or in the contract documents between TTL/Drash and Client, our scope of services for this Project did not include, either specifically or by implication, any environmental or biological assessment of the site or buildings, or any identification or prevention of pollutants, hazardous materials or conditions at the site or within buildings. If the Client is concerned about the potential for such contamination or pollution, TTL/Drash should be contacted to provide a scope of services to address the environmental concerns. Also, permitting, site safety, excavation support, and dewatering requirements are the responsibility of others. This geotechnical engineering report has been prepared for the exclusive use of our Client for specific application to this Project. This geotechnical engineering report has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, express or implied, are intended or made. Sterling Site Office Building 14

19 Should the nature, design, or location of the Project, as outlined in this geotechnical engineering report, be modified, geotechnical engineering recommendations and guidelines provided in this document will not be considered valid unless TTL/Drash reviews the changes and either verifies or modifies the applicable Project changes in writing. Sterling Site Office Building 15

20 EXHIBITS

21 N EAST COMMERCE STREET B-2 B-1 B-4 SOUTH HACKBERRY STREET B-3 SITE BOUNDARY GEOTECHNICAL BORING 1045 Central Parkway North, Suite 103 San Antonio, Texas Office: Facsimile: Project Mngr: Drawn By: Checked By: Reviewed By: PB AB PB CJD Project No. 116E Scale: NOT TO SCALE Date: SITE BORING LOCATION PLAN STERLING SITE OFFICE BUILDING COMMERCE STREET SAN ANTONIO, TEXAS EXHIBIT 1

22 SOIL SYMBOL PROJECT: CLIENT: FIELD DATA DEPTH (FT) SAMPLES Sterling Site Office Building Commerce Street San Antonio, Texas Jasmine Engineering San Antonio, Texas N: BLOWS/FT P: TONS/SQ FT T: TONS/SQ FT PERCENT RECOVERY/ ROCK QUALITY DESIGNATION N=5 MOISTURE CONTENT (%) 25 ATTERBERG LIMITS (%) LIQUID LIMIT LL 77 LABORATORY DATA PLASTIC LIMIT PL 25 PLASTICITY INDEX PI 52 DRY DENSITY (POUNDS/CU FT) COMPRESSIVE STRENGTH (TONS/SQ FT) LOG OF BORING FAILURE STRAIN (%) CONFINING PRESSURE (POUNDS/SQ IN) MINUS NO. 200 SIEVE (%) Dry augered from 0 to 30 feet. PROJECT NO. BORING NO. DATE SURFACE ELEVATION DRILLING METHOD(S): GROUNDWATER INFORMATION: Subsurface water was not encountered during drilling. 116E B-1 5/25/2017 Existing Grade PAGE 1 OF 1 DESCRIPTION OF STRATUM FAT CLAY with SAND (CH); medium stiff; dark brown N= N=5 33 N= FAT CLAY (CH); stiff to hard; light brown to tan 10 N= hydrocarbon (fuel) odor from about 8 feet to 11 feet - with gravel between 8.5 feet and 10 feet 116E Sterling Site Office Building - This Log is not valid if seperated from original report N=14 N=14 N=20 N= grades to tan and gray at 13.5 feet - with gypsum seam at 28.5 feet Boring Terminated at 30 feet. REMARKS The boring was backfilled with cuttings after completion of the subsurface water level observations. EXHIBIT 2

23 SOIL SYMBOL PROJECT: CLIENT: FIELD DATA DEPTH (FT) SAMPLES Sterling Site Office Building Commerce Street San Antonio, Texas Jasmine Engineering San Antonio, Texas N: BLOWS/FT P: TONS/SQ FT T: TONS/SQ FT PERCENT RECOVERY/ ROCK QUALITY DESIGNATION N=10 MOISTURE CONTENT (%) 33 ATTERBERG LIMITS (%) LIQUID LIMIT LL LABORATORY DATA PLASTIC LIMIT PL PLASTICITY INDEX PI DRY DENSITY (POUNDS/CU FT) COMPRESSIVE STRENGTH (TONS/SQ FT) LOG OF BORING FAILURE STRAIN (%) CONFINING PRESSURE (POUNDS/SQ IN) MINUS NO. 200 SIEVE (%) Dry augered from 0 to 30 feet. PROJECT NO. BORING NO. DATE SURFACE ELEVATION DRILLING METHOD(S): GROUNDWATER INFORMATION: Subsurface water was not encountered during drilling. 116E B-2 5/25/2017 Existing Grade PAGE 1 OF 1 DESCRIPTION OF STRATUM FAT CLAY with SAND (CH); medium stiff to stiff; dark brown N= N= with ferrous staining at 4.5 feet N=6 31 FAT CLAY (CH); stiff to hard; light brown - with gypsum seams between 6.5 feet and 10 feet 10 N= with gravel between 8.5 feet and 10 feet 116E Sterling Site Office Building - This Log is not valid if seperated from original report N=10 N=16 N=20 N= grades to tan and gray at 13.5 feet - with gypsum seam at 18.5 feet - grades to tan at 23.5 feet Boring Terminated at 30 feet. REMARKS The boring was backfilled with cuttings after completion of the subsurface water level observations. EXHIBIT 3

24 SOIL SYMBOL PROJECT: CLIENT: FIELD DATA DEPTH (FT) SAMPLES Sterling Site Office Building Commerce Street San Antonio, Texas Jasmine Engineering San Antonio, Texas N: BLOWS/FT P: TONS/SQ FT T: TONS/SQ FT PERCENT RECOVERY/ ROCK QUALITY DESIGNATION N=7 N=4 MOISTURE CONTENT (%) LL 78 LABORATORY DATA ATTERBERG LIMITS (%) LIQUID LIMIT PLASTIC LIMIT PL 29 PLASTICITY INDEX PI 49 DRY DENSITY (POUNDS/CU FT) COMPRESSIVE STRENGTH (TONS/SQ FT) DESCRIPTION OF STRATUM FAT CLAY with SAND (CH); medium stiff to stiff; dark brown N=7 32 Boring Terminated at 5 feet. 116E Sterling Site Office Building - This Log is not valid if seperated from original report. LOG OF BORING FAILURE STRAIN (%) CONFINING PRESSURE (POUNDS/SQ IN) MINUS NO. 200 SIEVE (%) Dry augered from 0 to 5 feet. PROJECT NO. BORING NO. DATE SURFACE ELEVATION DRILLING METHOD(S): GROUNDWATER INFORMATION: Subsurface water was not encountered during drilling. 116E B-3 5/25/2017 Existing Grade PAGE 1 OF 1 5 REMARKS The boring was backfilled with cuttings after completion of the subsurface water level observations. EXHIBIT 4

25 SOIL SYMBOL PROJECT: CLIENT: FIELD DATA DEPTH (FT) SAMPLES Sterling Site Office Building Commerce Street San Antonio, Texas Jasmine Engineering San Antonio, Texas N: BLOWS/FT P: TONS/SQ FT T: TONS/SQ FT PERCENT RECOVERY/ ROCK QUALITY DESIGNATION N=10 N=7 MOISTURE CONTENT (%) 6 10 LL 74 LABORATORY DATA ATTERBERG LIMITS (%) LIQUID LIMIT PLASTIC LIMIT PL 19 PLASTICITY INDEX PI 55 DRY DENSITY (POUNDS/CU FT) COMPRESSIVE STRENGTH (TONS/SQ FT) DESCRIPTION OF STRATUM FAT CLAY with GRAVEL (CH); stiff; light brown FAT CLAY with SAND (CH); stiff; brown N= grades to dark brown with ferrous staining at 3.5 feet Boring Terminated at 5 feet. 116E Sterling Site Office Building - This Log is not valid if seperated from original report. LOG OF BORING FAILURE STRAIN (%) CONFINING PRESSURE (POUNDS/SQ IN) MINUS NO. 200 SIEVE (%) Dry augered from 0 to 5 feet. PROJECT NO. BORING NO. DATE SURFACE ELEVATION DRILLING METHOD(S): GROUNDWATER INFORMATION: Subsurface water was not encountered during drilling. 116E B-4 5/25/2017 Existing Grade PAGE 1 OF 1 5 REMARKS The boring was backfilled with cuttings after completion of the subsurface water level observations. EXHIBIT 5

26 APPENDIX FIELD AND LABORATORY EXPLORATORY DRILLING PROGRAM LABORATORY TESTING PROGRAM NOTES REGARDING SOIL AND ROCK

27 EXPLORATORY DRILLING PROGRAM A truck-mounted, drilling rig was used to drill the exploratory borings and to recover soil/rock samples during the drilling. Soil samples were obtained by pushing thin wall tube samplers ( Shelby tube ) or with a splitbarrel ( split-spoon ) sampler while performing the Standard Penetration Test ( SPT ). Rock samples were obtained by performing the SPT or coring. When a soil sample was recovered using a Shelby tube sampler, a pocket penetrometer test ( PPT ) or hand torvane ( TV ) was conducted and recorded on the applicable exploratory field log of boring ( field log ). When a soil/rock sample was recovered using a split-barrel sampler, the SPT N-value was recorded on the applicable field log. The SPT procedure consists of driving the split-barrel into the subsurface stratum with a 140-pound hammer falling a distance of 30 inches. The number of blows ( N ) required to advance the splitspoon sampler the last 12 inches during a normal 18-inch penetration is the SPT resistance value or N-value. These N-values are indicated on each applicable field log at the depths of occurrence. The samples were sealed and transported to the laboratory for testing and classification. Our field representative prepared the field logs as part of the drilling operations. The field logs included visual classifications of the materials encountered during drilling, our field representative interpretation of the subsurface conditions between samples, and recording the results of various tests (N-values, PPT, and TV) performed during drilling and sampling. Each field log included with this Report represents our technical interpretation of the field log and includes modifications based on visual observations and testing of the samples in the laboratory. The scope of services for our geotechnical engineering services does not include addressing any environmental issues pertinent to the site. LABORATORY TESTING PROGRAM Samples retrieved during the field exploration were taken to the laboratory for further observation by one of our technical representatives, and they were classified in accordance with the Unified Soil Classification System (USCS). At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine the physical (index) and engineering properties of the soil/rock. Laboratory tests were conducted on selected soil samples and the test results are presented in this appendix. The laboratory test results were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. Laboratory tests were performed in general accordance with the applicable ASTM or other accepted standards. The following tests were conducted: Moisture Content Atterberg Limits Amount of Material In-Soil Finer than the N o 200 Mesh (75-µm) Sieve Sample Disposal All samples were returned to our laboratory. Unless stated otherwise in this Report or the Project contract, the samples not tested in the laboratory will be stored for a period of 30 days subsequent to submittal of this Report and will be discarded after this period, unless other arrangements are made prior to the disposal period.