Northside Independent School District HB Zachry Middle School Bus
Transcription
Northside Independent School District HB Zachry Middle School Bus
1512 South Flores Street San Antonio, Texas 78204 210.227.2612 210.227.9457 fax Date : 11/19/15 Northside Independent School District H.B. Zachry Middle School Bus Canopy Modifications RFCSP – 2015-160 ADDENDUM NO:1 Date: November 19, 2015 Project No: Alamo Architects Job No. 2015-33 Project Name: NISD H.B. Zachry Middle School Bus Canopy Modifications Owner: Northside Independent School District RE: 100% CONSTRUCTION DOCUMENTS This addendum shall be included in and be considered part of the plans and specifications for the above named project. The Contractor shall be required to sign an acknowledgment of the receipt of this addendum at the time she/he receives it. 1. This addendum contains changes to the requirements of the Contract Drawings and Specifications. Such changes shall be incorporated in the Contract Documents and shall apply to the work with the same meaning and force as if they had been included in the original Documents. Whenever this Addendum modifies a portion of a paragraph of the Specifications, or any portion of any Drawing, the remainder of the paragraph or drawings affected shall remain in force. 2. The conditions and terms of the basic specifications shall govern work described in this Addendum. Whenever performance and the quality of quantity of materials, or workmanship are not fully described in this Addendum, the PERFORMANCE REQUIREMENTS of the Specifications shall apply to the work described in this Addendum. Page 1 of 2 3. If no similar items of work are included in the basic specifications, the best quality of material and workmanship standards shall apply and all work shall be subject to the written approval of the Architect. GENERAL INFORMATION ITEM NO. 1-001 Attached: Sign In Sheet from the Pre-Proposal Meeting held on November 17, 2015. ITEM NO. 1-002 Attached: Geo-Tech Report by Terracon dated November 11, 2015 ITEM NO. 1-003 The Date and time for the Site Visit has been set for Monday November 23, 2015 at 1:30 pm, at the H.B. Zachry Middle School, 9410 Timber Path, San Antonio, TX 78250. END OF ITEMS Attachments included in this Addendum 01 are: (1 – 8 ½ x 11) Pre Proposal Conference Sign In Sheet (37 – 8 ½ x 11) Terracon Geo-Tech Report dated 11-11-15 Page 2 of 2 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop 9410 Timber Path San Antonio, Texas November 11, 2015 Terracon Project No. 90155253 Prepared for: Northside Independent School District San Antonio, Texas Prepared by: Terracon Consultants, Inc. San Antonio, Texas TABLE OF CONTENTS Page EXECUTIVE SUMMARY ............................................................................................................ i 1.0 INTRODUCTION ........................................................................................................... 1 2.0 PROJECT INFORMATION ............................................................................................ 1 2.1 Project Description .............................................................................................. 1 2.2 Site Location and Description ............................................................................. 2 3.0 SUBSURFACE CONDITIONS ....................................................................................... 2 3.1 Typical Profile ...................................................................................................... 2 3.2 Groundwater......................................................................................................... 3 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION. ...................................... 3 4.1 Geotechnical Considerations .............................................................................. 3 4.1.1 Expansive Soil Considerations ............................................................. 3 4.2 Earthwork ............................................................................................................. 4 4.2.1 General Site Preparation........................................................................ 4 4.2.2 Canopy Pad Preparation ........................................................................ 5 4.2.3 Fill Materials and Placement ................................................................. 5 4.2.4 Compaction Requirements .................................................................... 6 4.2.5 Grading and Drainage ............................................................................ 6 4.2.6 Earthwork Construction Considerations .............................................. 7 4.3 Foundations ......................................................................................................... 7 4.3.1 Slab-On-Grade Foundation .................................................................... 7 4.3.2 Slab-On-Grade Construction Considerations ...................................... 9 4.3.3 Drilled Pier Foundations ........................................................................ 9 4.3.4 Drilled Pier Construction Considerations............................................11 4.3.5 Foundation Construction Monitoring ..................................................13 4.4 Seismic Considerations .................................................................................... 13 4.5 Pavements .......................................................................................................... 13 4.5.1 Design Recommendations ...................................................................13 4.5.2 Pavement Section Materials .................................................................15 4.5.3 Pavement Joints and Reinforcement ...................................................17 5.0 GENERAL COMMENTS ...............................................................................................18 TABLES Table 1 Lateral Soil Parameters APPENDIX A Exhibit A-1 Exhibit A-2 Exhibit A-3 Exhibit A-4 and A-5 Site Location Plan Boring Location Plan Field Exploration Description Boring Logs Responsive ■ Resourceful ■ Reliable TABLE OF CONTENTS (Continued) APPENDIX B Exhibit B-1 Laboratory Testing APPENDIX C Exhibit C-1 Exhibit C-2 General Notes Unified Soil Classification System Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 EXECUTIVE SUMMARY This summary should be used in conjunction with the entire report for design purposes. It should be recognized that details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The section titled GENERAL COMMENTS should be read for an understanding of the report limitations. This geotechnical study has been performed for the proposed bus canopy and bus loop to be located inside H.B. Zachry Middle School campus at 9410 Timber Path in San Antonio, Texas. Two borings were drilled to depths of about 5 and 30 feet below the existing grade within the proposed development area. Based on the information obtained from our subsurface exploration, the subsurface soil conditions appear to be suitable to support the proposed structure provided the canopy pad area is properly prepared and foundations properly designed. Pertinent geotechnical issues include the following: The subsurface conditions consist of Gravelly Fat Clay (CH) underlain by Lean Clay (CL) and Marl. The Potential vertical Rise (PVR) at this site is about 2 to 2½ inches. Groundwater was not encountered during or after the drilling activities. Both shallow and deep foundation systems may be considered to support the proposed canopy. The 2012 International Building Code, Table 1613.3.2 IBC seismic site classification for this site is Class “C”. Both flexible and rigid pavements can be considered for the project. Responsive ■ Resourceful ■ Reliable i GEOTECHNICAL ENGINEERING REPORT H.B. ZACHRY MS BUS CANOPY AND BUS LOOP 9410 TIMBER PATH SAN ANTONIO, TEXAS TERRACON PROJECT NO. 90155253 NOVEMBER 11, 2015 1.0 INTRODUCTION Terracon Consultants, Inc. (Terracon) is pleased to submit our Geotechnical Engineering Report for the proposed bus canopy and bus loop to be located inside H.B. Zachry Middle School campus at 9410 Timber Path, San Antonio, Texas. The project scope was performed in general accordance with Terracon Proposal No. P90150906 dated October 19, 2015. The purposes of this report are to describe the subsurface conditions observed at the borings drilled for this study, analyze and evaluate the test data, and provide recommendations with respect to: subsurface soil conditions earthwork seismic considerations groundwater conditions foundation design and construction pavement design and construction Boring B-2 was drilled to a depth of only 6 feet as some obstruction was encountered during drilling. Based on a discussion with Mr. James Berg with NISD, it was decided not to extend the boring or relocate to another location. 2.0 2.1 PROJECT INFORMATION Project Description Item Site layout Description See Exhibits A-1 & A-2, Site Location Plan & Boring Location Plan Construction New bus canopy and new bus loop. Finished Floor Elevation Not available at the time of this report. Responsive ■ Resourceful ■ Reliable 1 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 2.2 Site Location and Description Item Location Existing improvements Current ground cover Existing topography 3.0 3.1 Description The site is located at H.B. Zachry Middle School campus. Site address is 9410 Timber Path in San Antonio, Texas. School buildings and pavements. Asphalt pavement. The site appeared to be relatively flat and level. SUBSURFACE CONDITIONS Typical Profile Based on the results of the borings, subsurface conditions on the project site can be generalized as follows: Description Approximate Depth of Stratum (feet) --- --- Stratum I 0.5 to 6 GRAVELLY FAT CLAY (CH) brown, tan and gray Stratum II 6 to 20 LEAN CLAY (CL) 2 ; brown Consistency/ Density Material Encountered Asphalt thickness – 1 inch Granular Base Material – 4 to 10 inches 1 ; dark --Medium Stiff to Very Stiff Very Stiff to Hard 3 Stratum III 20 to 30 MARL ; tan Hard 1 The GRAVELLY FAT CLAY (CH) materials could undergo high high volumetric changes (shrink/swell) should they experience changes in their in-place moisture content. 2 The LEAN CLAY (CL) materials could undergo low to moderate volumetric changes (shrink/swell) should they experience changes in their in-place moisture content. 3 The MARL is defined in ASTM D 653-90 Standard Terminology Relating to Soil, Rock and Contained Fluids as ”calcareous clay usually containing from 35 to 65 percent calcium carbonate." The calcium carbonate is an indication of a cemented matrix of sand, silt, or clay. When submerged in water, marl will begin to slake. However, when being excavated or drilled this material typically behaves more like a rock than soil thereby requiring construction equipment and procedures typically used for rock. This material is not anticipated to undergo volumetric changes with fluctuations in moisture content. Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Details of the borings can be found on the boring logs in Appendix A of this report. Responsive ■ Resourceful ■ Reliable 2 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 3.2 Groundwater Groundwater generally appears as either a permanent or temporary water source. Permanent groundwater is generally present year round, which may or may not be influenced by seasonal and climatic changes. Temporary groundwater water is also referred to as a “perched” water source, which generally develops as a result of seasonal and climatic conditions. The borings were dry-augered to their full depths in an attempt to observe for the presence of subsurface water. Subsurface water was not observed in the borings. Groundwater levels are influenced by seasonal and climatic conditions which generally result in fluctuations in the elevation of the groundwater level over time. Therefore, the foundation contractor should check the groundwater conditions just before foundation excavation activities. The borings were backfilled with soil cuttings and patched with cold mix after the drilling operations were completed. 4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION. The following recommendations are based upon the data obtained from our field and laboratory programs, project information provided to us and on our experience with similar subsurface and site conditions. 4.1 Geotechnical Considerations Based on a discussion with the Structural Engineer Mr. Richard Gates, P.E. with Persyn Engineering, we understand that the proposed canopy may be supported by a slab-on-grade foundation system. In order to support the structures on shallow foundations, preparation of the subgrade will be required to reduce the PVR. Alternatively, a drilled pier foundation may also be used to support the canopy structure. The foundation being considered to provide support for the planned structure must satisfy two independent engineering criteria with respect to the subsurface conditions encountered at this site. One criterion is the foundation system must be designed with an appropriate factor of safety to reduce the possibility of a bearing capacity failure of the soils underlying the foundation when subjected to axial and lateral load conditions. The other criterion is movement of the foundation system due to compression (consolidation or shrinkage) or expansion (swell) of the underlying soils must be within tolerable limits for the structure. 4.1.1 Expansive Soil Considerations Based on our findings, the subsurface soils at this site generally exhibit a high expansion potential. Based on the information developed from our field and laboratory programs and on method TEX-124-E in the Texas Department of Transportation (TxDOT) Manual of Testing Procedures, we estimate that the subgrade soils at this site exhibit a Potential Vertical Rise (PVR) of about 2 to 2½ inches in its present condition. The actual movements could be greater Responsive ■ Resourceful ■ Reliable 3 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 if inadequate drainage, ponded water, and/or other sources of moisture are allowed to infiltrate beneath the structure after construction. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and cracking in the canopy structure should be anticipated. The severity of cracking and other damage such as uneven slabs will probably increase if any modification of the site results in excessive wetting or drying of the expansive soils. Site grades should provide effective drainage away from the structure during and after construction. Water permitted to pond next to the structure can result in greater soil movements than those discussed in this report. These greater movements can result in unacceptable differential floor slab movements, cracked slabs and walls, and roof leaks. Estimated movements described in this report are based on effective drainage for the life of the structure and cannot be relied upon if effective drainage is not maintained. Recommendations for preparing the pad to reduce soil movements are provided in the Pad Preparation section of this report. Proper water management is important. Recommendations regarding this issue are included in the Grading and Drainage section of this report. 4.2 Earthwork The following presents recommendations for general site preparation, pad preparation and placement of engineered fills on the project. The recommendations presented for design and construction of earth supported elements including foundations, slabs and pavements are contingent upon following the recommendations outlined in this section. Earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project. 4.2.1 General Site Preparation Construction operations may encounter difficulties due to the 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 Compaction Requirements section of this report, one of the following measures may be required: removal and replacement with select fill; drying by natural means if the schedule allows. Prior to construction, any vegetation, pavements, and any otherwise unsuitable materials should be removed from the construction area. Wet or dry material should either be removed or moisture conditioned and recompacted. After stripping and grubbing, the subgrade should be proof-rolled where possible to aid in locating loose or soft areas. Proof-rolling can be performed Responsive ■ Resourceful ■ Reliable 4 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 with a 15-ton roller or fully loaded dump truck. Soils that are observed to rut or deflect excessively (typically greater than 1-inch) under the moving load should be undercut and replaced with properly compacted on-site soils. The proof-rolling and undercutting activities should be witnessed by a representative of the geotechnical engineer and should be performed during a period of dry weather. 4.2.2 Canopy Pad Preparation The following subgrade preparation recommendations should be performed for slab-on-grade foundations prior to foundation construction in order to reduce the PVR to 1-inch. If no subgrade preparation is performed, movement of the canopy flatwork up to about 2½ inches should be expected. After removing the existing pavements, excavate and remove 4 feet of the subgrade soil from the canopy par area. The pad area includes the limits of the proposed structure plus a 3-foot (horizontal) overbuild beyond proposed perimeter of the structure and any movement sensitive flatwork. The exposed subgrade in the pad should be proof rolled with at least a 15-ton roller, or fully loaded dump truck, to evidence any weak yielding zones. A Terracon geotechnical engineer or their representative should be present to observe proof rolling operations. Over-excavate any confirmed weak yielding zones, both vertically and horizontally, to expose competent soil. The exposed subgrade should be moisture conditioned between -2 and +3 percentage points of the optimum moisture content and then compact to at least 95 percent of the maximum dry density determined in accordance with ASTM D 698. After proofrolling and the replacement of weak yielding zones with competent soil, place select fill to achieve the desired pad elevation. The select fill should be placed in loose lifts of no more than 8 inches, be moisture conditioned between -2 and +3 percentage points of the optimum moisture content, and then compacted to at least 95 percent of the maximum dry density determined in accordance with ASTM D 698. This method should result in at least 4 feet of select fill soils beneath the grade supported slab. 4.2.3 Fill Materials and Placement Select fill and on-site soils should meet the following criteria: Fill Type 1 USCS Classification Granular select fill 2 Varies Responsive ■ Resourceful ■ Reliable Acceptable Location for Placement All locations and elevations. 5 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 Fill Type 1 USCS Classification Acceptable Location for Placement The CH soils are not suitable for use as select fill. On-Site Soils CH, CL CL, SC, GC Select Fill (LL≤40) and (7≤PI≤20) CL soils may be used as select fill provided they meet the criteria of this report. All locations and elevations. 1 Controlled, compacted fill should consist of approved materials that are free of organic matter and debris or materials exceeding 3 inches in maximum dimension. A sample of each material type should be submitted for testing. 2 Granular select fill should be cohesive crushed limestone base material with a maximum aggregate size of 3 inches. Plasticity Index should range from 5 to 20. 3 A pulverized, well graded uniform mixture of the existing asphaltic concrete and granular base may be suitable for use as granular select fill if it meets the recommended criteria in this report. The material should be uniformly mixed and have particles no larger than 2 inches. 4.2.4 Compaction Requirements Subsequent to proofrolling, and just prior to placement of any fill, the exposed subgrade within the construction area should be evaluated for moisture and density. If the moisture, density, and/or the requirements do not meet the criteria described in the table below, the subgrade should be scarified to a depth of 6 inches; moisture adjusted and compacted to at least 95 percent of the Standard Effort (ASTM D 698) maximum dry density. ITEM DESCRIPTION 1 All fill should be placed in thin, loose lifts of about 8 inches, Fill Lift Thickness with compacted thickness not to exceed 6 inches. Compaction of Select Fill, On-Site Soil 95 percent of the material’s standard Proctor maximum dry and Granular Material density (ASTM D 698). The materials should be moisture conditioned between -2 Moisture Content of On-Site Soil, Select and +3 percentage points of the optimum moisture Fill and Granular Material content. 1 Unless otherwise noted within this report all compaction requirements are provided above. 4.2.5 Grading and Drainage Effective drainage should be provided during construction and maintained throughout the life of the new improvements. After construction and landscaping, we recommend verifying final grades to document that effective drainage has been achieved. Grades around the structure should also be periodically inspected and adjusted as necessary, as part of the structure’s maintenance program. Water permitted to pond next to the structure can result in distress in the structure including unacceptable differential floor slab movements, cracked slabs and walls, and roof leaks. Grade supported slab and foundation performances described in this report are based on effective Responsive ■ Resourceful ■ Reliable 6 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 drainage for the life of the structure and cannot be relied upon if effective drainage is not maintained. Planters and other surface features which could retain water in areas adjacent to the structures should be properly drained, designed, sealed or eliminated. Landscaped irrigation adjacent to the foundation systems should be properly designed and controlled to help maintain a relatively constant moisture content within 5 feet of the structure. Collect roof runoff in drains or gutters. Discharge roof drains and downspouts onto pavements and/or flatwork which slope away from the structure or extend downspouts a minimum of 5 feet away from the structure. 4.2.6 Earthwork Construction Considerations It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. Based upon the subsurface conditions determined from the geotechnical exploration, subgrade soils exposed during construction are anticipated to be relatively stable. However, the stability of the subgrade may be affected by precipitation, repetitive construction traffic or other factors. If unstable conditions develop, workability may be improved by scarifying and drying. Over excavation of wet zones and replacement with granular materials may be necessary. Lightweight excavation equipment may be required to reduce subgrade pumping. The use of remotely operated equipment, such as a backhoe, would be beneficial to perform cuts and reduce subgrade disturbance. All temporary excavations should be sloped or braced as required by Occupational Health and Safety Administration (OSHA) regulations to provide stability and safe working conditions. Temporary excavations will probably be required during grading operations. The grading contractor, by his contract, is usually responsible for designing and constructing stable, temporary excavations and should shore, slope or bench the sides of the excavations as required, to maintain stability of both the excavation sides and bottom. All excavations should comply with applicable local, state and federal safety regulations, including the current OSHA Excavation and Trench Safety Standards. 4.3 Foundations The types and depths of foundations suitable for given structures depend on several factors including the subsurface conditions, the functions of the structures, the loads they will carry, and the cost of the foundations. Recommendations for slab-on-grade foundation systems and drilled piers are provided in the following sections. 4.3.1 Slab-On-Grade Foundation A slab-on-grade foundation may be considered to support the proposed canopy. Parameters commonly used to design this type of foundation are provided on the table below. The slab foundation design parameters presented on the table below are based on the criteria published by the Wire Reinforcing Institute (WRI). These are essentially empirical design methods and Responsive ■ Resourceful ■ Reliable 7 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 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 design manual. Prepared Subgrade 1 Conventional Method Net Allowable Bearing Pressures 2 Subgrade Modulus (k) Potential Vertical Rise (PVR) 1 2,000 psf 80 pci About 1 inch WRI Method Effective Plasticity Index (PI) 3 Soil / Climate Rating Factor (1- C) 30 0.16 1 Based on preparing the pad as discussed in the report. 2 The net allowable bearing pressure provided above includes a Factor of Safety (FS) of at least 3. The WRI effective PI is equal to the near surface PI if that PI is greater than all of the PI values in the upper 15 feet. 3 We recommend that the grade beams be at least 30 inches below final grade. These recommendations are for proper development of bearing capacity for the continuous beam sections of the foundation system and to reduce the potential for water to migrate beneath the slab foundation. These recommendations are not based on structural considerations. Grade beam depths may need to be greater than recommended herein for structural considerations and should be properly evaluated and designed by the Structural Engineer. The grade beams or slab portions may be thickened and widened to serve as spread footings at concentrated load areas. An allowable lateral resistance developed by friction between the bottom of the foundation and the underlying soils of 400 psf may be used. The allowable lateral resistance is based on a factor of safety of approximately 2. The passive resistance acting on the foundation can be calculated using an allowable of 150 psf per foot of depth. The allowable passive pressure is based on a factor of safety of about 2. Unless pavements or on-grade slabs are provided up to and above the footings, the passive resistance for soil in the upper 1 foot of the final grade should be neglected. For a slab foundation system designed and constructed as recommended in this report, post construction settlements should be less than 1 inch. Settlement response of a select fill supported slab is influenced more by the quality of construction than by soil-structure interaction. Therefore, it is essential that the recommendations for foundation construction be strictly followed during the construction phases of the pad and foundation. The use of a vapor retarder should be considered beneath concrete slabs-on-grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the Responsive ■ Resourceful ■ Reliable 8 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 slabs will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 for procedures and cautions about the use and placement of a vapor retarder. 4.3.2 Slab-On-Grade Construction Considerations Grade beams for the slab foundation should preferably be neat excavated. Excavation should be accomplished with a smooth-mouthed bucket. If a toothed bucket is used, excavation with this bucket should be stopped 6 inches above final grade and the grade beam excavation completed with a smooth-mouthed bucket or by hand labor. Debris in the bottom of the excavation should be removed prior to steel placement. The foundation excavations should 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 excavation, it should be collected and removed and not allowed to adversely affect the quality of the bearing surface. Special care should be taken to protect the exposed soils from being disturbed or drying out prior to placement of the concrete. 4.3.3 Drilled Pier Foundations As an alternative, drilled piers may be considered to support the proposed canopy. The canopy structure may be supported on straight-sided piers bearing at a minimum depth of 15 feet below existing grade. The piers may be designed for a net allowable bearing pressure of 10,000 psf with a factor of safety against a bearing capacity failure of approximately 3. An allowable side shear value of 1,000 psf, with an assumed factor of safety of at least two (2), may be used to aid in resisting axial compressive loads on the piers. The side shear should be neglected for the upper five (5) feet of soil in contact with the pier shaft. Piers should not extend deeper than 30 feet below existing grade without contacting our office. Minimum pier spacing should be at least three pier diameters center to center, with the larger pier diameter controlling the spacing. If design or construction considerations require that the pier spacing is less than mentioned above, Terracon should be contacted to evaluate the pier capacity. In addition to the axial compressive loads on the piers, these piers will also be subjected to axial tension loads due to the near surface clay soils and possibly due to other induced structural loading conditions. To compute the axial tension force due to the swelling soils along the pier shaft, the following equation may be used. Qu = 35 d Qu d = = Uplift force due to expansive soil conditions in kips (k) Diameter of pier shaft in feet (ft) Where: Responsive ■ Resourceful ■ Reliable 9 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 This calculated force can be used to compute the longitudinal reinforcing steel required in the pier to resist the uplift force induced by the swelling clays. However, the cross-sectional area of the reinforcing steel should not be less than one (1) percent of the gross cross-sectional area of the drilled pier shaft. The reinforcing steel should extend from the top to the bottom of the shaft to resist this potential uplift force. For the straight-sided drilled piers, the uplift force due to swelling soils and any other axial tension forces due to structural loading conditions can be resisted by the allowable side-shear of the drilled pier. The allowable uplift resistance of the straight sided drilled piers can be evaluated using the following equation: Where: Qar = 2· d · Dp + 0.9W p + PDL Qar = Allowable uplift resistance of pier in kips (k) d Dp = = Wp PDL = = Diameter of pier shaft in feet (ft) Founding depth of pier in natural soils minus the upper 5 feet of shaft in contact with the soil in feet (ft) Weight of the drilled pier in kips (k) Permanent sustained dead Load acting on the drilled pier in kips (k) The structural engineer may want to factor the dead load value based on their degree of certainty. For single, isolated drilled piers, total settlements, based on the indicated bearing pressures for the structure, should be about 1 inch for properly designed and constructed drilled piers. Settlement beneath individual piers will be primarily elastic with most of the settlement occurring during construction. Differential settlement may also occur between adjacent piers. The amount of differential settlement between adjacent piers could approach 50 to 75 percent of the total pier settlement. Settlement response of drilled piers is impacted more by the quality of construction than by soil-structure interaction. Improper pier installation could result in differential settlements significantly greater than we have estimated. In addition, larger magnitudes of settlement should be expected if the soil is subjected to bearing pressures higher than the allowable values presented in this report. Lateral Loading - The piers supporting the canopy may be subjected to lateral loading. The criteria for lateral load analysis is presented in Table 1 are for use with the computer program LPILE. A number of methods, including hand solutions and computer programs, are available for calculating the lateral behavior of piles and drilled piers. The majority of these methods rely on “key” soil parameters such as soil elastic properties (E and k s), strain at 50 percent of the principal stress difference (50), undrained shear strength (c), and load-deflection (p-y) criteria. The p-y criteria, which are commonly used to model soil reaction, were developed from Responsive ■ Resourceful ■ Reliable 10 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 instrumented load tests and are generally considered to provide the best model of soil behavior under short-term lateral loading. Factors of safety are not generally applied to the lateral load analysis. A performance criteria, or “limit state”, are usually considered. For most foundations subjected to lateral loads, the pier foundation is designed with a limit of 1 inch of deflection at the top of the pier and 1 degree of rotation as measured from the vertical axis of the pier. The analysis is generally conducted using the working loads and the limit state values. The applied loads are then doubled to evaluate the deflection and rotation at the top of the pier to determine if the foundation will topple over under extreme overload. This overload condition may indicate that the foundation would deflect or rotate such that the tower will tilt but the foundation will not experience failure. Structural limits, such as moment capacity and shear, may control the design and should be evaluated by the Structural Engineer. 4.3.4 Drilled Pier Construction Considerations The pier excavations should be augered and constructed in a continuous manner. Steel and concrete should be placed in the pier excavations immediately following drilling and evaluation for proper bearing stratum, embedment, and cleanliness. Under no circumstances should the pier excavations remain open overnight. Due to the presence of hard clay and marl (rock like), the contractor should be prepared to use high torque, high powered (rock) equipment. During the time of our drilling operations, subsurface water was not encountered. Subsurface water levels are influenced by seasonal and climatic conditions which result in fluctuations in subsurface water elevations. The contractor should be prepared to use temporary casing should water be encountered and/or sloughing of the excavation sidewalls occur. It is the responsibility of the foundation contractor to choose the casing, type, depth and method of installation. The casing method is discussed in the following paragraphs. Casing Method- Casing should provide stability of the excavation walls and should reduce water influx; however, casing may not completely eliminate subsurface water influx potential. In order for the casing to be effective, a “water tight” seal must be achieved between the casing and surrounding soils. The drilling subcontractor should determine casing depths and casing procedures. Water that accumulates in excess of 3 inches in the bottom of the pier excavation should be pumped out prior to steel and concrete placement. If the water is not pumped out, a closed-end tremie should be used to place the concrete completely to the bottom of the pier excavation in a controlled manner to effectively displace the water during concrete placement. If water is not a factor, concrete may be placed with a short tremie so the concrete is directed to the bottom of the pier excavation. The concrete should not be allowed to ricochet off the walls of the pier excavation nor off the reinforcing steel. If this operation is not successful or to the satisfaction of the foundation contractor, the pier excavation should be flooded with fresh water to offset the differential water pressure caused by the unbalanced water levels inside Responsive ■ Resourceful ■ Reliable 11 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 and outside of the casing. The concrete should be tremied completely to the bottom of the excavation with a closed-end tremie. Removal of casing should be performed with extreme care and under proper supervision to reduce mixing of the surrounding soil and water with the fresh concrete. Rapid withdrawal of casing or the auger may develop suction that could cause the soil to intrude into the excavation. An insufficient head of concrete in the casing during its withdrawal could also allow the soils to intrude into the wet concrete. Both of these conditions may induce “necking”, a section of reduced diameter, in the pier. All aspects of concrete design and placement should comply with the American Concrete Institute (ACI) 318 Code Building Code Requirements for Structural Concrete, ACI 336.1 Standard Specification for the Construction of Drilled Piers, and ACI 336.3R entitled Suggested Design and Construction Procedures for Pier Foundations. Concrete should be designed to achieve the specified minimum 28-day compressive strength when placed at a 7 inch slump with a 1 inch tolerance. Adding water to a mix designed for a lower slump does not meet the intent of this recommendation. If a high range water reducer is used to achieve this slump, the span of slump retention for the specific admixture under consideration should be thoroughly investigated. Compatibility with other concrete admixtures should also be considered. A technical representative of the admixture supplier should be consulted on these matters. Successful installation of drilled piers is a coordinated effort involving the general contractor, design consultants, subcontractors and suppliers. Each must be properly equipped and prepared to provide their services in a timely fashion. Several key items of major concern are: Proper drilling rig with proper equipment (including casing, augers). Reinforcing steel cages tied to meet project specifications; Proper scheduling and ordering of concrete for the piers; and Monitoring of installation by design professionals. Pier construction should be carefully monitored to assure compliance of construction activities with the appropriate specifications. A number of items of concern for pier installation include those listed below. Pier locations Vertical alignment Competent bearing Steel placement Responsive ■ Resourceful ■ Reliable Concrete properties and placement Casing removal (if required) Proper casing seal for subsurface water control 12 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 If the contractor has to deviate from the recommended foundations, Terracon should be notified immediately so additional engineering recommendations can be provided for an appropriate foundation type. 4.3.5 Foundation Construction Monitoring The performance of the foundation system for the proposed structure will be highly dependent upon the quality of construction. Thus, we recommend that fill pad compaction and foundation installation be monitored full time by an experienced Terracon soil technician under the direction of our Geotechnical Engineer. During foundation installation, the base should be monitored to evaluate the condition of the subgrade. We would be pleased to develop a plan for compaction and foundation installation monitoring to be incorporated in the overall quality control program. 4.4 Seismic Considerations Description 2012 International Building Code Site Classification (IBC) 1 Value C2 Site Latitude (Degrees) 29.49276˚ N Site Longitude (Degrees) 98.68145° W Mapped Spectral Acceleration for Short Periods (0.2-Second): (SS) 3 0.073 g Mapped Spectral Acceleration for a 1-Second Period: (S1) 3 0.026 g 1 The site class definition was determined using SPT N-values in conjunction with section 1613.3.2 in the 2012 IBC and Table 20.3-1 in the 2010 ASCE-7. 2 Boring extended to a maximum depth of 30 feet, and this seismic site class definition considers that stiff soil continues below the maximum depth of the subsurface exploration. 3 The Spectral Acceleration values were determined using publicly available information provided on the United States Geological Survey (USGS) website. The spectral acceleration values can be used to determine the site coefficients using Tables 1613.3.3 (1) and 1613.3.3 (2) in the 2012 IBC. 4.5 Pavements 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 trash removal trucks. Due to the presence of expansive clay subgrade, pavement movements up to 2½ inches should be expected. If pavement movements are to be reduced to tolerable levels, the pavement should be prepared as the canopy pad. 4.5.1 Design Recommendations For this project Light, Medium and Heavy pavement section alternatives have been provided. Light is for areas expected to receive only car traffic. Medium refers to secondary drive areas expected Responsive ■ Resourceful ■ Reliable 13 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 to receive delivery vans and student pick-up/drop off area. Heavy assumes areas with heavy traffic, such as trash pickup areas, main access drive areas, bus lanes and fire lanes. 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 Medium; Class 2 for Heavy). The rigid pavement section was designed using the American Concrete Institute (ACI 330R-01) method (Traffic Category A (ADTT=0) for Light and Medium; A-1 (ADTT=10) for Heavy). If heavier traffic loading is expected, Terracon should be provided with the information and allowed to review these pavement sections. Minimum Recommended Flexible Pavement Section Thickness Raw Subgrade Modified Subgrade Light Medium Heavy Light Medium Heavy Duty Duty Duty Duty Duty Duty (inches) (inches) (inches) (inches) (inches) (inches) Hot Mix Asphaltic Concrete 2.0 2.0 3.0 2.0 2.0 3.0 10.0 14.0 16.0 6.0 10.0 12.0 Lime Treated Subgrade ---- ---- ---- 6.0 6.0 6.0 Moisture Conditioned Subgrade 6.0 6.0 6.0 ---- ---- ---- Granular Base Material 1, 2 1 Asphaltic base material (Type A or B) may be used in place of crushed limestone base material. Every 2½ inches of crushed limestone base material may be replaced with 1 inch of asphaltic base material. However, the minimum thickness of the asphaltic base material is 4 inches. 2 Tensar Geogrid (TX-130) may be used to reduce the thickness of the Granular Base by 2 inches. The Geogrid should be placed at the bottom of the base layer. Minimum Recommended Rigid Pavement Section Thickness Raw Subgrade Modified Subgrade Light Medium Heavy Light Medium Heavy Duty Duty Duty Duty Duty Duty (inches) (inches) (inches) (inches) (inches) (inches) Reinforced Concrete 5.5 6.5 7.0 5.0 6.0 6.5 Lime Treated Subgrade ---- ---- ---- 6.0 6.0 6.0 Moisture Conditioned Subgrade 6.0 6.0 6.0 ---- ---- ---- 1 Dumpster area should be constructed as heavy duty rigid section. Proper perimeter drainage is very important and should 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 area. Responsive ■ Resourceful ■ Reliable 14 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 Curbs should extend through the base and at least 3 inches into the soil subgrade 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 concrete-asphalt interfaces. Pavement areas that will be subjected to heavy wheel and traffic volumes, 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 should 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. The pavement section has been designed using generally recognized structural coefficients for the pavement materials. These structural coefficients reflect the relative strength of the pavement materials and their contribution to the structural integrity of the pavement. If the pavement does not drain properly, it is likely that ponded water will infiltrate the pavement materials resulting in a weakening of the materials. As a result, the structural coefficients of the pavement materials will be reduced and the life and performance of the pavement will be shortened. 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. 4.5.2 Pavement Section Materials Presented below are selection and preparation guidelines for various materials that may be used to construct the pavement sections. Submittals should be made for each pavement material. The submittals should be reviewed by the Geotechnical Engineer and appropriate members of the design team and 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 should be plant mixed, hot laid Type C or D Surface. The asphaltic concrete base course should also be plant mixed, hot laid Type A or B. Each mix should meet the master specifications requirements of 2004 TxDOT Standard Specifications Item 341, Item SS 3224 (2011) and specific criteria for the job mix formula. The mix should be compacted between 91 and 95 percent of the Responsive ■ Resourceful ■ Reliable 15 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 maximum theoretical density as measured by TEX-227-F. The asphalt cement content by percent of total mixture weight should fall within a tolerance of ±0.3 percent asphalt cement from the specific mix. In addition, the mix should 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 should be PG 64-22 or higher performance grade. Aggregates known to be prone to stripping should not be used in the hot mix. If such aggregates are used measures should be taken to mitigate this concern. The mix should 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. Unless otherwise shown on the plans, the Contractor shall be responsible for obtaining the required pavement specimens at their expense and in a manner and at locations selected by the Engineer. Concrete - Concrete should have a minimum 28-day design compressive strength of 4,000 psi. Granular Base Material - Base material may be composed of crushed limestone base/ crushed concrete meeting all of the requirements of 2004 TxDOT Item 247, Type A, Grade 1 or 2; including triaxial strength. The material should be compacted to at least 95 percent of the maximum dry density as determined in accordance with ASTM D 1557 at moisture contents ranging from -2 and +3 percentage points of the optimum moisture content. Lime Treated Subgrade - The subgrade may be treated with hydrated lime in accordance with TxDOT Item 260 in order to improve its strength and improve its load carrying capacity. We anticipate that approximately 6 percent hydrated lime will be required. This is equivalent to about 30 pounds of hydrated lime per square yard for a 6-inch treatment depth. However, the actual percentage should be determined by laboratory tests on samples of the clayey subgrade prior to construction. The optimum lime content should result in a soil-lime mixture with a pH of at least 12.4 when tested in accordance with ASTM C 977, Appendix XI and should reduce the Plasticity Index to 20 or less. The lime should initially be blended with a mixing device such as a Pulvermixer, sufficient water added, and be allowed to cure for at least 48 hours. After curing, the lime-soil should be remixed to meet the in-place gradation requirements of Item 260 and compacted to at least 95 percent of the maximum dry density Responsive ■ Resourceful ■ Reliable 16 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 determined in accordance with ASTM D 698 at moisture contents ranging from optimum and + 4 percentage points above the optimum moisture content. Moisture Conditioned Subgrade - The subgrade should be scarified to a depth of 6 inches and then moisture conditioned between -2 and +3 percentage points of the optimum moisture content, and then compact to at least 95 percent of the maximum dry density determined in accordance with ASTM D 698. Details regarding subgrade preparation, fill materials, placement and compaction are presented in Earthwork section under subsections Fill Materials and Placement and Compaction Requirements. 4.5.3 Pavement Joints and Reinforcement 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: 12½ feet each way for pavement thickness of 5 or 5½ inches; 15 feet each way for pavement thickness of 6 or greater. Contraction Joint Depth: At least ¼ of pavement thickness. Contraction Joint Width: One-fourth inch or as required by joint sealant manufacturer. Construction Joint Spacing: 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. Construction Joint Depth/Width: Full depth of pavement thickness. Construct sealant reservoir along one edge of the joint. Width of reservoir to be ¼ inch or as required by joint sealant manufacturer. Depth of reservoir to be at least ¼ of pavement thickness. Isolation Joint Spacing: As required to isolate pavement from structures, etc. Isolation Joint Depth: Full depth of pavement thickness. Isolation Joint Width: One-half to 1 inch or as required by the joint sealant manufacturer. None (see note below) Expansion Joint: Note: Long, linear pavements may require expansion joints. However, in this locale, drying shrinkage of concrete typically significantly exceeds anticipated expansion Responsive ■ Resourceful ■ Reliable 17 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 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 be also become a maintenance problem. All joints should be sealed. If all joints, including sawcuts, are not sealed then expansion joints should be installed. Distributed Steel: Steel reinforcement may consist of steel bars described as follows: No 3 reinforcing steel bars at 18 inches on-center-each-way, Grade 60. No 4 reinforcing steel bars at 24 inches on-center-each-way, Grade 60. Note: It is imperative that the distributed steel be positioned accurately in the pavement cross section, namely 2 inches from the top of the pavement. All construction joints have dowels. presented as follows: Pavement Thickness: Dowels: Dowel Spacing: Dowel Length: Dowel Embedment: 5.0 Dowel information varies with pavement thickness as 5 to 5½ inches ⅝ inch diameter 12 inches on center 12 inches long 5 inches 6 to 6½ inches ¾ inch diameter 12 inches on center 14 inches long 6 inches 7 inches 7 /8 inch diameter 12 inches on center 14 inches long 6 inches GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated location and from other information discussed in this report. This report does not reflect variations that may occur across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. Responsive ■ Resourceful ■ Reliable 18 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. Responsive ■ Resourceful ■ Reliable 19 TABLE Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 TABLE 1 LATERAL DESIGN PARAMETERS H.B. ZACHRY MS BUS CANOPY AND BUS LOOP 9410 TIMBER PATH SAN ANTONIO, TEXAS TERRACON PROJECT NO. 90155253 Layer 1 2 3 4 Depth to Bottom of Layer (feet) 5 8 20 30 Effective Unit Weight (pcf) 120 120 120 125 Undrained Shear Strength (psf) 1,000 2,000 4,000 5,000 Soil Strain Factor (50) 0.010 0.007 0.005 0.004 LPILE Soil Types Stiff Clay without Free Water Stiff Clay without Free Water Stiff Clay without Free Water Stiff Clay without Free Water Subgrade Modulus, k (pci) 425 620 1,200 1,395 1 Design depth to subsurface water is greater than 30 feet. 2 Stratigraphy shown above is based on our interpretation of soil strength and may not correspond with the descriptive classifications shown on the boring logs. 3 The lateral load criteria shown above are for use in the computer programs LPILE. Table 1 APPENDIX A DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES Project Manager: Project No. AB Drawn by: AB Checked by: MTG Approved by: MTG 90155253 AERIAL PHOTOGRAPHY PROVIDED BY MICROSOFT BING MAPS SITE LOCATION PLAN Exhibit H.B. Zachry MS Bus Canopy and Bus Loop 9410 Timber Path San Antonio, Texas A-1 Scale: AS SHOWN File Name: 90155253 Date: 11/4/2015 6911 Blanco Road San Antonio, TX 78216-6164 DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES Project Manager: Project No. AB Drawn by: AB Checked by: MTG Approved by: MTG 90155253 AERIAL PHOTOGRAPHY PROVIDED BY MICROSOFT BING MAPS BORING LOCATION PLAN Exhibit H.B. Zachry MS Bus Canopy and Bus Loop 9410 Timber Path San Antonio, Texas A-2 Scale: AS SHOWN File Name: 90155253 Date: 11/4/2015 6911 Blanco Road San Antonio, TX 78216-6164 Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 FIELD EXPLORATION DESCRIPTION A truck-mounted, rotary drill rig equipped with continuous flight augers was used to advance the borehole. Soil samples were obtained by split-barrel sampling procedures. In the split-barrel sampling procedure, a standard 2-inch O.D. split-barrel sampling spoon is driven into the ground with a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the standard penetration resistance value. These values are indicated on the boring logs at the depths of occurrence. If the sampler was driven less than the final 12 inches, the N value is recorded on the log as the number of blows and amount of penetration. However, if the sampler was not driven the initial 6-inch seating increment with 50 hammer blows, refusal (i.e. “ref) is recorded along with the inches driven on the log. Our field representative prepared the field log as part of the drilling operations. The field log included visual classifications of the materials encountered during drilling and our field representative interpretation of the subsurface conditions between samples. Each boring log included with this report represents the engineer’s/geologist’s interpretation of the field log and include 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. Responsive ■ Resourceful ■ Reliable Exhibit A-3 BORING LOG NO. B-1 PROJECT: H.B. Zachry MS Bus Canopy and Bus Loop CLIENT: Northside ISD San Antonio, Texas about 1 inch Base Material 10 inches STRATUM I GRAVELLY FAT CLAY (CH); dark brown and brown, very stiff 6-7-10 N=17 6-11-12 N=23 5 6.0 STRATUM II LEAN CLAY with GRAVEL (CL); brown, very stiff to hard - fat clay layer between 8 and 10 feet 10 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 90155253.GPJ 15 20.0 20 STRATUM III MARL; tan, hard 25 30.0 30 Boring Terminated at 30 Feet Stratification lines are approximate. In-situ, the transition may be gradual. ATTERBERG LIMITS LL-PL-PI PERCENT FINES DEPTH 0.1 Asphalt 0.9 WATER CONTENT (%) Longitude: -98.68145° FIELD TEST RESULTS Latitude: 29.49276° SAMPLE TYPE LOCATION See Exhibit A-2 WATER LEVEL OBSERVATIONS 9410 Timber Path San Antonio, Texas DEPTH (Ft.) GRAPHIC LOG SITE: Page 1 of 1 16 20 68-24-44 4-8-13 N=21 16 58-21-37 10-19-25 N=44 11 20-38-50/4" N=88/10" 12 15-32-50/3" N=82/9" 9 15-30-41 N=71 11 15-50/6" N=50/6" 8 35-50/3" N=50/3" 4 39 58-18-40 69 Hammer Type: Automatic Advancement Method: Flight Auger Notes: Abandonment Method: Backfilled with Auger Cuttings Surface capped with asphalt WATER LEVEL OBSERVATIONS No free water observed 6911 Blanco Road San Antonio, Texas Boring Started: 10/31/2015 Boring Completed: 10/31/2015 Drill Rig: CME 75 Driller: Project No.: 90155253 Exhibit: A-4 BORING LOG NO. B-2 PROJECT: H.B. Zachry MS Bus Canopy and Bus Loop CLIENT: Northside ISD San Antonio, Texas about 1 inch Base Material 4 inches STRATUM I GRAVELLY FAT CLAY (CH); dark brown, medium stiff to very stiff 3-5-7 N=12 5 6.0 ATTERBERG LIMITS LL-PL-PI PERCENT FINES DEPTH 0.1 Asphalt 0.3 WATER CONTENT (%) Longitude: -98.681569° FIELD TEST RESULTS Latitude: 29.492419° SAMPLE TYPE LOCATION See Exhibit A-2 WATER LEVEL OBSERVATIONS 9410 Timber Path San Antonio, Texas DEPTH (Ft.) GRAPHIC LOG SITE: Page 1 of 1 1161 70-26-44 4-4-6 N=10 26 72-23-49 55 2-2-2 N=4 22 71-20-51 54 THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 90155253.GPJ Boring Terminated at 6 Feet Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic Advancement Method: Flight Auger Notes: Abandonment Method: Backfilled with Auger Cuttings Surface capped with asphalt WATER LEVEL OBSERVATIONS No free water observed 6911 Blanco Road San Antonio, Texas Boring Started: 10/31/2015 Boring Completed: 10/31/2015 Drill Rig: CME 75 Driller: Project No.: 90155253 Exhibit: A-5 APPENDIX B Geotechnical Engineering Report H.B. Zachry MS Bus Canopy and Bus Loop■ San Antonio, Texas November 11, 2015 ■ Terracon Project No. 90155253 LABORATORY TESTING Samples retrieved during the field exploration were taken to the laboratory for further observation by the project geotechnical engineer and were classified in accordance with the Unified Soil Classification System (USCS) described in this Appendix. At that time, the field descriptions were confirmed or modified as necessary and an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. 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, local or other accepted standards. Selected soil samples obtained from the site were tested for the following engineering properties: In-situ Water Content Atterberg Limits Amount of Material In-Soil Finer than the No 200 Mesh (75-µm) Sieve Sample Disposal All samples were returned to our laboratory. 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. Responsive ■ Resourceful ■ Reliable Exhibit B-1 APPENDIX C GENERAL NOTES DESCRIPTION OF SYMBOLS AND ABBREVIATIONS Macro Core Ring Sampler Rock Core Grab Sample No Recovery (HP) Hand Penetrometer Water Level After a Specified Period of Time (T) Torvane (b/f) Standard Penetration Test (blows per foot) (PID) Photo-Ionization Detector (OVA) Organic Vapor Analyzer Water Level After a Specified Period of Time FIELD TESTS Shelby Tube Split Spoon WATER LEVEL SAMPLING Auger Water Initially Encountered Water levels indicated on the soil boring logs are the levels measured in the borehole at the times indicated. Groundwater level variations will occur over time. In low permeability soils, accurate determination of groundwater levels is not possible with short term water level observations. DESCRIPTIVE SOIL CLASSIFICATION Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. LOCATION AND ELEVATION NOTES Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic maps of the area. STRENGTH TERMS RELATIVE DENSITY OF COARSE-GRAINED SOILS (More than 50% retained on No. 200 sieve.) Density determined by Standard Penetration Resistance Includes gravels, sands and silts. CONSISTENCY OF FINE-GRAINED SOILS (50% or more passing the No. 200 sieve.) Consistency determined by laboratory shear strength testing, field visual-manual procedures or standard penetration resistance Descriptive Term Standard Penetration or Ring Sampler Descriptive Term Unconfined Compressive Standard Penetration or Ring Sampler N-Value N-Value Blows/Ft. (Consistency) Strength, Qu, tsf Blows/Ft. (Density) Blows/Ft. Blows/Ft. Very Loose 0-3 0-6 Very Soft less than 0.25 0-1 <3 Loose 4-9 7 - 18 Soft 0.25 to 0.50 2-4 3-4 Medium Dense 10 - 29 19 - 58 Medium-Stiff 0.50 to 1.00 4-8 5-9 Dense 30 - 50 59 - 98 Stiff 1.00 to 2.00 8 - 15 10 - 18 Very Dense > 50 > _ 99 Very Stiff 2.00 to 4.00 15 - 30 19 - 42 Hard > 4.00 > 30 > 42 RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Term(s) of other constituents Trace With Modifier Percent of Dry Weight < 15 15 - 29 > 30 GRAIN SIZE TERMINOLOGY Major Component of Sample Boulders Cobbles Gravel Sand Silt or Clay RELATIVE PROPORTIONS OF FINES Descriptive Term(s) of other constituents Trace With Modifier Percent of Dry Weight <5 5 - 12 > 12 Particle Size Over 12 in. (300 mm) 12 in. to 3 in. (300mm to 75mm) 3 in. to #4 sieve (75mm to 4.75 mm) #4 to #200 sieve (4.75mm to 0.075mm Passing #200 sieve (0.075mm) PLASTICITY DESCRIPTION Term Plasticity Index Non-plastic Low Medium High 0 1 - 10 11 - 30 > 30 Exhibit C-1 UNIFIED SOIL CLASSIFICATION SYSTEM Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Coarse Grained Soils: More than 50% retained on No. 200 sieve Gravels: More than 50% of coarse fraction retained on No. 4 sieve Sands: 50% or more of coarse fraction passes No. 4 sieve Silts and Clays: Liquid limit less than 50 Fine-Grained Soils: 50% or more passes the No. 200 sieve Silts and Clays: Liquid limit 50 or more Highly organic soils: A B C D E Clean Gravels: Less than 5% fines C Gravels with Fines: More than 12% fines C Clean Sands: Less than 5% fines D Sands with Fines: More than 12% fines D Inorganic: Organic: Inorganic: Organic: Cu = D60/D10 Cc = (D 30 ) 2 D 10 x D 60 F G If soil contains 15% sand, add “with sand” to group name. If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. Group Name B Cu 4 and 1 Cc 3 E GW Well-graded gravel F Cu 4 and/or 1 Cc 3 E Fines classify as ML or MH GP Poorly graded gravel F GM Silty gravel F,G, H Fines classify as CL or CH GC Clayey gravel F,G,H Cu 6 and 1 Cc 3 E SW Well-graded sand I SP Poorly graded sand I SM Silty sand G,H,I SC Clayey sand G,H,I Cu 6 and/or 1 Cc 3 Fines classify as ML or MH E Fines Classify as CL or CH PI 7 and plots on or above “A” line PI 4 or plots below “A” line Liquid limit - oven dried Liquid limit - not dried CL Lean clay K,L,M J ML Silt K,L,M 0.75 OL J Organic clay K,L,M,N Organic silt K,L,M,O PI plots on or above “A” line CH Fat clay K,L,M PI plots below “A” line Liquid limit - oven dried MH Elastic Silt K,L,M Liquid limit - not dried Primarily organic matter, dark in color, and organic odor Based on the material passing the 3-in. (75-mm) sieve If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name. Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay Group Symbol H I J K L M N O P Q 0.75 OH PT Organic clay K,L,M,P Organic silt K,L,M,Q Peat If fines are organic, add “with organic fines” to group name. If soil contains 15% gravel, add “with gravel” to group name. If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,” whichever is predominant. If soil contains 30% plus No. 200 predominantly sand, add “sandy” to group name. If soil contains 30% plus No. 200, predominantly gravel, add “gravelly” to group name. PI 4 and plots on or above “A” line. PI 4 or plots below “A” line. PI plots on or above “A” line. PI plots below “A” line. Exhibit C-2 1512 South Flores Street San Antonio, Texas 78204 210.227.2612 210.227.9457 fax Date : 11/30/15 Northside Independent School District H.B. Zachry Middle School Bus Canopy Modifications RFCSP – 2015-160 ADDENDUM NO:2 Date: November 30, 2015 Project No: Alamo Architects Job No. 2015-33 Project Name: NISD H.B. Zachry Middle School Bus Canopy Modifications Owner: Northside Independent School District RE: 100% CONSTRUCTION DOCUMENTS This addendum shall be included in and be considered part of the plans and specifications for the above named project. The Contractor shall be required to sign an acknowledgment of the receipt of this addendum at the time she/he receives it. 1. This addendum contains changes to the requirements of the Contract Drawings and Specifications. Such changes shall be incorporated in the Contract Documents and shall apply to the work with the same meaning and force as if they had been included in the original Documents. Whenever this Addendum modifies a portion of a paragraph of the Specifications, or any portion of any Drawing, the remainder of the paragraph or drawings affected shall remain in force. 2. The conditions and terms of the basic specifications shall govern work described in this Addendum. Whenever performance and the quality of quantity of materials, or workmanship are not fully described in this Addendum, the PERFORMANCE REQUIREMENTS of the Specifications shall apply to the work described in this Addendum. Page 1 of 2 3. If no similar items of work are included in the basic specifications, the best quality of material and workmanship standards shall apply and all work shall be subject to the written approval of the Architect. GENERAL INFORMATION ITEM NO. 2-001 Attached: Plan Holders List date 11-30-15. PROJECT DRAWINGS Civil: ITEM NO. 2-002 Refer to the attached Civil Addendum No.2 dated - 11-24-30 for Revisions and Clarifications. Architectural: ITEM NO. 2-003 SHEET - A1.0, DETAIL 1 – BUS CANOPY PLAN & DETAIL 10 - TRECH DRAIN DETAIL: Change reference to Downspout detail from 4/A4.10 to 5/A4.10. ITEM NO. 2-004 SHEET - A1.0, DETAIL 3 – CANOPY ROOF PLAN: Change reference to Roofing Control Joint detail from 5/A4.10 to 3/A4.10. END OF ITEMS Attachments included in this Addendum 02 are: (1 – 8 ½ x 11) Plan Holders List dated 11-30-15 (1 – 8 ½ x 11) M.W. Cude – Addendum No. 2 dated 11-24-15 Page 2 of 2 1512 South Flores Street San Antonio, Texas 78204 210.227.2612 November 30, 2015 210.227.9457 fax NISD Zachry MS Bus Canopy Renovation San Antonio, Texas Alamo Architects Job No. 2015-33 Company Name Contact Person Phone & Fax area code (210) unless otherwise noted RL Rohde GC Alfonso Sanin Marksmen GC Mandy Baublit Suburban Construction Gaylon Loontjer Baron Long Construction John Long WR Griggs Construction Troy Griggs 649-3130 649-3110 379-5353 346-6026 349-5812 377-1586 377-0397 830.931.2121 830.931.2111 General or Sub Date Set Rcv’d G 11/11/15 G 11/13/15 G 11/19/15 G 11/19/15 G 11/20/15 2015-33 Bidder's List