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Denton Tap L2R BA-LR 970702 GEOTECHNICAL EXPLORATION on GYM N_~".STICS CENTER Denton Tap Road N at Sandy Lake Road Coppell, Texas ALPHA Report No. 97445 Prepared for SUPERIOR STRUCTURAL SYSTEMS 449 Harris, Suite N 103 Coppell, Texas July 2, 1997 PREPARED BY: Alpha Testing, Inc. 2209 Wisconsin Road Suite 100 Dallas, Texas 75229 July 2, 1997 SUPERIOR STRUCTURAL SYSTEMS 449 Harris, Suite N 103 Coppell, Texas 75019 Attention: Mr. Ross R. Rains Re: Geotechnical Exploration GYMNASTICS CENTER Denton Tsp Road N at Sandy Lake Road Coppell, Texas ALPHA Report No. 97445 Attached is the report of the geotechnical exploration performed for the project referenced above. This study has been authorized by Mr. Ross R. Rains on June 23, 1997 and performed in accordance with ALPHA Proposal No. GT 4101 dated June 19, 1997. This report contains results of field explorations and laboratory testing and an engineering interpretation of these with respect to available project characteristics. The results and analyses have been used to develop recommendations to aid design and construction of foundations and pavement. ALPHA TESTING, INC. appreciates the opportunity to be of service on this project. If we can be of further assistance, such as providing materials testing services during construction, please contact our office. Sincerely yours, ALPHA TESTING, INC. David A. Lewis, P.E. Manager of Engineering Services Jim L. Hillhouse, P.E. President DALiJLH!pc Copies: (3) Client GEOTECHNICAL EXPLORATION on GYMNASTICS CENTER Denton Tap Road N at Sandy Lake Road Coppell, Texas ALPHA Repod No. 97445 TABLE OF CONTENTS 1.0 PURPOSE AND SCOPE ...................................... 1 2.0 PROJECT CHARACTERISTICS ................................ 2 3.0 FIELD EXPLORATION ....................................... 2 4.0 LABORATORY TESTS ..................................... 3 5.0 GENERAL SUBSURFACE CONDITIONS ......................... 3 6.0 DESIGN RECOMMENDATIONS ............................... 4 6.1 Slab-on-Grade ....................................... 6 6.2 Piers (Alternate) ....................................... 7 6.3 Floor Slab - Pier Supported Building ......................... 8 6.4 Pavement ........................................... 9 6.4.1 Asphaltic Concrete Pavement ............................. 9 6.4.2 Portland Cement Pavement .............................. 10 6.4.3 Pavement Specifications ................................ 11 6.5 DRAINAGE .............................................. 1 1 7.0 GENERAL CONSTRUCTION PROCEDURES AND RECOMMENDATIONS .................................. 12 7.1 Site Preparation and Grading ............................ 13 7.2 Foundation Excavations ................................ 13 7.3 Fill Compaction ...................................... 15 7.4 Groundwater ........................................ 16 RECOMMENDED SPECIFICATIONS FOR CONTROLLED EARTHWORK ON HOUSING AND URBAN DEVELOPMENT PROJECTS ............ 12 Table of Contents (cont'd) APPENDIX A-1 METHODS OF FIELD EXPLORATION BORING LOCATION PLAN - Figure - 1 B-1 METHODS OF LABORATORY TESTING RECORD OF SUBSURFACE EXPLORATION KEY TO SOIL SYMBOLS AND CLASSIFICATIONS ALPHA Report No. 97445 1.0 PURPOSE AND SCOPE The purpose of this geotechnical exploration is to evaluate some of the physical and engineering properties of subsurface materials at the subject site with respect to formulation of appropriate geotechnical design parameters for the proposed construction. The field exploration has been accomplished by securing subsurface soil and rock (shale) samples from widely spaced test borings performed across the expanse of the site. Engineering analyses have been ,, performed from results of the field exploration and results of laboratory tests performed on representative samples. The analyses have been used to develop ~ geotechnical engineering design parameters for foundations and pavement to be ii constructed on the project. ' Also included is an evaluation of the site with respect to potential construction problems and recommendations concerning earthwork and quality control testing ': during construction. This information can be used to verify subsurface conditions i! and to aid in ascertaining all construction phases meet project specifications. i I Recommendations provided in this report have been developed from information obtained in test borings which depict subsurface conditions only at the specific boring locations and at the particular time designated on the logs. Subsurface conditions at other locations may differ from those observed at the boring '. locations. The scope of work is not intended to fully define the variability of ' subsurface materials which may be present on the site. The nature and extent of variations between borings may not become evident until construction. If significant variations then appear evident, our office should be contacted to re-evaluate our recommendations after performing on-site observations and tests. Professional services provided in this geotechnical exploration have been performed, findings obtained and recommendations prepared in accordance with generally accepted geotechnical engineering principles and practices. The scope of services provided herein does not include an environmental assessment of the site or investigation for the presence or absence of hazardous materials in the soil. surface water or groundwater. ALPHA TESTING, INC. is not responsible for conclusions, opinions or recommendations made by others based on this data. Information contained in this report is intended for exclusive use of the Client (and their design " representatives) and design of specific structures outlined in Section 2.0. Recommendations presented in this report should not be used for design of any other structures except those specifically described in this report. Further. 1 ALPHA Report No. 97445 subsurface conditions can change with passage of time. Recommendations contained herein are not considered applicable for an extended period of time after the completion date of this report. It is recommended our office be contacted for a review of the contents of this report for construction commencing more than one (1) year after completion of this report. Recommendations provided in this report are based on our understanding of information provided by the Client about characteristics of the project. If the Client notes any deviation from the facts about project characteristics, our office should be contacted immediately since this may materially alter the recommendations. Further, ALPHA TESTING, INC. is not responsible for damages resulting from workmanship of designers or contractors and it is recommended that qualified personnel be retained by the owner to verify work is performed in accordance with plans and specifications. 2.0 PROJECT CHARACTERISTICS It is proposed to construct a new gymnastics building on a site located generally northwest of the existing Albertson's retail store located at Denton Tap Road N and Sandy Lake Road in Coppell, Texas. A site plan illustrating the general outline of the property is provided as Figure 1, the Boring Location Plan, in the Appendix of this report. At the time the field exploration was performed, most of the site was relatively open and free of any heavy vegetation. Cursory visual observations indicate the proposed construction site is relatively level. Present plans provide for the construction of a new gymnastics center. The new structure is anticipated to be a single story structure and is anticipated to create light loads to be carried by the foundations. It is anticipated the new structure will be supported using either a slab-on-grade or drilled pier foundations. Pavement will consist of either asphaltic concrete or portland-cement concrete pavement. No other information, including site grading, was provided during this study. 3.0 FIELD EXPLORATION Subsurface conditions on the site have been explored by drilling three (3) test borings in general accordance with ASTM D 420 to a depth of up to 25 ft using standard rotary drilling equipment. The approximate location of each test boring is shown on the Boring Location Plan, Figure 1, enclosed in the Appendix of this report. Details of drilling and sampling operations are briefly summarized in " Methods of Field Exploration, Section A-1 of the Appendix. Soil and rock (shale) types encountered during the field exploration are presented :1 on Record of Subsurface Exploration sheets included in the Appendix of this report. The boring logs contain our Field Technician's and Engineer's 2 ALPHA Report No. 97445 interpretation of conditions believed to exist between actual samples retrieved. Therefore, these boring logs contain both factual and interpretive information. Lines delineating subsurface strata on the boring logs are approximate and the actual transition between strata may be gradual. Apparent, or possible, fill materials have been encountered at some boring locations as will De discussed in Section 5.0. There may be fill in other borings or at other locations, but could not be readily identified. Composition of the fill has been evaluated based on samples retrieved from 6-inch maximum diameter holes. Since no records are known to exist of fill placement, compaction or uniformity, subsurface conditions immediately adjacent to test borings can be substantially different than conditions observed in test borings. Fill placed ut;der non-controlled engineering conditions can contain other materials (deleterious or non-deleterious) not discovered in the borings and can be subject to unpredictable movements. 4.0 LABORATORY TESTS Selected samples of the subsurface materials have been tested in the laboratory to evaluate their engineering properties as a basis in providing recommendations for foundation design and earthwork construction. A brief description of testing procedures used in the laboratory can be found in Methods of Laboratory Testing, Section B-1 of the Appendix. Individual test results are presented either on Record of Subsurface Exploration sheets or on summary data sheets also enclosed in the Appendix. 5.0 GENERAL SUBSURFACE CONDITIONS Within the 25-ft maximum depth explored on the site, subsurface materials consist generally of sandy clay (CL) underlain by sand (SP) and deeper shale. The letters in parenthesis represent the soils' classification according to the Unified Soil Classification System (ASTM D 2488). Following is a brief summary of the more predominant strata encountered and some engineering properties of the subsurface stratigraphy. More detailed stratigraphic information is presented on the Record of Subsurface Exploration Sheets attached to this report. 1. The surface layer of soil encountered consists generally of sandy clay and varies in thickness from about 4 to 15 ft. The upper 4 ft of sandy clay in Borings 1 and 2 appears to be fill, or possible fill. Results of Atterberg- limit tests indicate the sandy clay (fill and natural) is slightly to moderately plastic and can be expected to swell and shrink with corresponding 3 ALPHA Report No. 97445 variations in moisture content. The sandy clay (fill and natural) is generally firm to hard in consistency. 2. Below the surficial sandy clay soil, generally sand was noted and varies in thickness from about 3 to 12.5 ft. Results of standard penetration tests performed in the field indicate the sand is in a compact to very dense condition. 3. Shale was encountered at depths of about 16.5 to 18 ft below the existing ground surface. Results of Texas Cone Penetration tests performed in the field indicate the shale is competent. The subsurface clayey materials are relatively impermeable and are anticipated to have a slow response to water movement. However, the sand is relatively permeable and would have a more rapid response to water movement. Therefore, several days of observation will be required to evaluate actual groundwater levels within the depths explored. Also, the groundwater level at the site is anticipated to fluctuate seasonally dependin9 on the amount of rainfall, prevailing weather conditions and subsurface drainage characteristics. During field explorations, free groundwater has been' noted on drilling tools and in open boreholes upon completion at depths of about 10 to 11 ft. In our opinion, the current groundwater level on the site may be located at a depth of about 10- 11 ft. It is not uncommon to detect seasonal groundwater either from natural fractures within the clayey or granular matrix, near the soil/rock interface or from fractures in the rock, particularly after a wet season. If more detailed groundwater information is required, monitorin9 wells or piezometers can be installed. Further details concerning subsurface materials and conditions encountered can be obtained from the Record of Subsurface Exploration sheets provided in the Appendix of this report. 6.0 DESIGN RECOMMENDATIONS The following design recommendations have been developed on the basis of the previously described Project Characteristics (Section 2.0) and Subsurface Conditions (Section 5.0). If project criteria change, including project location on the site, our office should conduct a review to determine if modifications to the recommendations are required. Further, it is recommended our office be provided with a copy of the final plans and specifications for review prior to construction. As stated in Section 5.0, about 4 ft of fill (or possible fill) is present in the vicinity of Borings 1 and 2. There may be fill in other areas but could not be readily :1 I 4 " I ALPHA Report No. 97445 identified during our investigation. If the existing fill was not placed under engineering supervision and with field density tests performed routinely on each lift of fill, the following recommendations are provided in descending order of preference: 1. The most positive method of utilizing the existing fill is to totally excavate the existing fill in the building pad area and then re-place the fill under engineering supervision as outlined in Section 7.3 of this report. 2. Another method of utilizing the existing fill is to perform density tests in a series of test pits to evaluate the condition, composition and compaction of the existing fill. !t should be recognized ALPHA was not present when the subject fill was placed and can make no definitive statement about areas not tested. We can only provide generalized opinions about the fill based on the condition of the fill tested at the test pit locations. Fill conditions at other locations could be different than in the specific areas tested. Assuming the fill tested meets the minimum acceptable compaction guidelines, we could provide a statement indicating that based on results of field density tests and visual observations of the fill, it is our opinion the present strength and condition of the fill tested is suitable for direct support of slab-on-grade foundations. If the fill tested is not satisfactory for support of slab-on-grade foundations, recommendations will be provided for improving the fill. If more specific details are desired describing , procedures to evaluate fill using test pits, our office should be contacted. 3. An alternate method is to over-excavate the existing fill to a depth of at least 2 ft below the bottom of the fboor slab in the building pad area. The :1 exposed surface should then be scarified to a depth of at least 6 inches and re-compacted to at least 98 percent of standard Proctor maximum dry density (ASTM D 698) and within the range of 0 to 4 percentage points above the material's optimum moisture content. Finally, the exposed surface should be proof-rolled with heavy equipment (10 ton minimum total weight) and further tested by probing as necessary. After re-compaction. proof-rolling and testing the exposed surface, any weak or highly organic soils noted should be removed. Upon completion ofthe above proof-rolling and monitoring, soils previously over-excavated can be re-placed provided they are free of any deleterious !1 materials and are compacted to at least 98 percent of standard Proctor maximum dry density (ASTM D 698) and within the range of 0 to 4 percentage points above the material's optimum moisture. 5 ALPHA Report No. 97445 If compaction records are obtained later and verify the entire depth of fill was placed under engineering supervision, the exposed surface of the fill should be proof-rolled with a heavy roller to detect any possible weak areas. Any weak soils identified as part of the proof-rolling process should be removed and replaced with well-compacted soil as outlined in Section 7.3 of this report. The exact lateral extent of existing fill cannot be determined from the spacing of test borings and from visual observations on the site. In lieu of performing additional borings to identify the extent of fill, the above inspection and improvement procedures can commence at the location of borings with fill " (Borings 1 and 2) and extend outward in building areas (plus 2-ft) until natural subgrade materials are encountered, or until the bu.ld ng limits (plus 2-ft) are reached. It is recommended the lateral extent of fill be confirmed by a Professional Engineer, or his representative. 6.1 Slab-on-Grade Our findings indicate a slab-on-grade foundation could experience soil-related potential movements of up to about 1.5 inches (Potential Vertical Rise, PVR) if constructed within 1.5 ft of existing grade. This potential movement has been estimated using methods outlined by Texas Highway Department Test Method Tex-124-E and engineering judgement and experience. Estimated movements have been calculated assuming the moisture content of the in-situ soil within the normal zone of seasonal moisture content change varies from a "dry" condition to a "wet" condition as defined by Tex-124-E. Movements exceeding those predicted above could occur if positive drainage of surface water is not maintained or if soils are subject to an outside water source, such as leakage from a utility line or subsurface moisture migration from off-site locations. If the above estimated potential movement (1.5 inches) is considered excessive, movement of the slab foundation could be reduced to about 1 inch by providing at least 1 ft of select, non-expansive soil between the bottom of the floor slab and the top surface of the underlying materials. 1. All non-expansive fill or replacement soils should consist of a select material having a liquid limit less than 35 and a plasticity index (PI) not less ,. ii than about 4 nor greater than 15. 2. Select fill should be compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698) and within the range of 1 !i percent below to 3 percentage points above the material's optimum '! moisture content. ALPHA Report No. 97445 3. A slab foundation constructed on at least 1 ft of select, non-expansive fill could experience potential movements of up to about 1 inch (Potential Vertical Rise, PVR). 4. In major entrance areas, the select fill should extend at least 10 ft beyond the perimeter of the building. However, select fill extending beyond buildin9 lines should be capped with a 1-ft thick layer of clayey type soil (plasticity index of at least 30) compacted as recommended in Section 7.3 to inhibit infiltration of surface water into the select fill and below the building. In all other areas, the select fill should preferably not extend beyond the building limits. The slab should be designed with exterior and interior grade beams adequate to provide sufficient rigidity to the foundation system. A net allowable soil bearing pressure of 2.5 kips per sq ft may be used for design of all grade beams bearing on either improved existing fill or new fill soils as recommended in Section 7.3. Grade beams should bear a minimum depth of 12 inches below final grade and should have a minimum width of 10 inches. To reduce cracking as normal movements occur in foundation soils, all grade beams and floor slabs should be adequately reinforced with steel. Also, a moisture barrier of polyethylene sheeting or similar material should be placed between the slab and subgrade soils to retard moisture migration through the slab. Further, a thin layer of clean sand can be placed over the moisture barrier to improve concrete curing and reduce the potential for surface cracking. The above design criteria given in this report have been developed assumin9 the slab is constructed within 1.5 ft of existing grade. Substantial cutting and filling on the site (more than 1.5 ft) can alter the recommended foundation design parameters. Therefore, it is recommended our office be contacted following completion of any substantial amount of cutting and filling on 'site to verify the appropriate design parameters are utilized for final foundation design. 6.2 Piers (Alternate) Alternately, our findings indicate the structural frame and walls for the proposed building can be supported by a system of drilled, straight-shaft piers. These piers should be brought to bear at least 2 ft into the underlyin9 gray shale. Information obtained from the test borings indicates the minimum depth of the piers will vary from about 18.5 to 20 ft below the existing ground surface. It should be noted, water bearin9 sand was encountered above the shale at about 10-11 ft. Therefore, casing of piers will be required to control water seepa9e and sloughing of soils. 7 ALPHA Report No. 97445 Piers can be dimensioned based on a net allowable end-bearing pressure of 15 kips per sq ft and skin friction (in compression) of 2 kips per sq ft. The skin friction component should be applied only to the portion of the shaft located in the gray shale (neglecting the upper 2 ft of 9ray shale). However, no more than 60 percent of the load carrying capacity of the pier should be attributed to skin friction. Further, the minimum clear spacing between piers should be at least two pier shaft diameters to develop the full load carrying capacity from skin friction. The above bearing capacity contains a factor of safety of at least 3 considerin9 a general bearing capacity failure and the skin friction value has a factor of safety of at least 2. Normal elastic settlement of piers under loading is estimated at less than about 0.75 inches. Each pier should be designed to resist the uplift pressure (soil-to-pier adhesion) due to potential soil swell along the shaft from post construction heave and other uplift forces applied by structural loadings. The magnitude of uplift adhesion due to soil swell along the pier shaft cannot be defined accurately and can vary according to the actual in-place moisture content of the soils during construction. It is estimated this uplift adhesion will not exceed about 0.75 kips per sq ft. This soil adhesion is approximated to act uniformly over the upper 10 ft of the pier shaft. The uplift adhesion due to soil swell can be neglected over the portion of the shaft in contact with any select, non-expansive soil. The uplift resistance of each pier can be computed using an allowable skin friction value of 1.5 kips per sq ft acting uniformly over the portion of the shaft bearing in the gray shale. The top 2 ft of gray shale should be neglected in computing the uplift resistance of each pier. This uplift resistance value has a factor of safety of at least 2. All grade beams should be formed with a nominal 4-inch void at the bottom. " Commercially available cardboard box forms (cartons) are made for this purpose. The cardboard cartons should extend the full length and width of the grade ' beams. Prior to concrete placement, cartons should be inspected to verify they are firm, properly placed, and capable of supporting wet concrete. Some type of permanent soil retainer, such as pre-cast concrete panels, must be provided to i prevent soils adjacent to grade beams from sloughing into the void space at the bottom of the grade beams. Additionally, backfill soils placed adjacent to grade beams must be compacted as outlined in Section 7.3 of this report. 6.3 Floor Slab - Pier Supported Building A floor slab supported on grade could experience potential movements of up to about 1.5 inches (Potential Vertical Rise, PVR). If these movements are considered excessive, the most positive floor system for the building supported 8 ALPHA Report No. 97445 on piers is a slab suspended completely above the existing expansive soils. At least 4 inches of void space should be provided between the bottom of the floor slab and top surface of the underlying expansive clays. Provisions should be made for (a) adequate drainage of the under-floor space and (b) differential movement of utility lines. An alternate solution for the floor system of the building consists of a concrete slab designed to bear uniformly on select, non-expansive fill. Movement of the floor slab can be reduced to about 1 inch by improving subsurface conditions beneath the slab as previously discussed in Section 6.1 of this report. If a soil-supported floor slab is utilized, a "floating" (fully ground supported, and not structurally connected to walls or foundations) floor slab is recommended. This reduces the possibility of cracking and displacement of the floor slab due to differential movements between the slab and foundation. These movements can be detrimental to a slab that is rigidly connected to the foundation. Floor slab dowelled into perimeter grade beams can develop a plastic hinge (crack) parallel to and approximately 5 to 10 ft inside the building perimeter. Formation of this plastic hinge may be controlled by constructing a joint in the floor slab in the area of the anticipated hinge location. In certain areas, construction of a "floating" slab may be difficult or impractical. In these areas, increasing reinforcement and slab thickness may be necessary to prevent the potential movements from cracking the slab. A moisture barrier of polyethylene sheeting or similar material should be placed between the slab and subgrade soils to retard moisture migration through the slab. Further, a thin layer of clean sand can be placed over the moisture barrier to improve concrete curing and reduce the potential for surface cracking. 6.4 Pavement Sandy clay soils encountered near the existing ground surface will probably constitute the subgrade for most parking and drive areas. Therefore. it is recommended these soils be improved prior to construction of pavement. To permit correlation between information from test borings and actual subgrade conditions exposed during construction, a qualified Geotechnical Engineer should be retained to provide subgrade monitoring and testing during construction. If there is any change in project criteria, the recommendations contained in this report should be reviewed by our office. 6.4.1 Asphaltic Concrete Pavement After final subgrade elevation in parking and drive areas is achieved, the exposed surface of the pavement subgrade soils should be scarified to a depth of at least 9 ALPHA Report No. 97445 6 inches. Then, the scarified soils should be compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698) and within the range of 1 percent below to 2 percentage points above the material's optimum moisture content. California Bearing Ratio (CBR) tests have not been performed for this specific project, but previous experience with similar soils indicates the CBR value for the existing sandy clay will be in the range of 8 to 10. Using the above CBR values and assuming normal traffic for a 15-year project life, the following pavement sections are recommended: ~ 1. The pavement section in parking areas can consist of at least 5 inches '1 of asphaltic concrete composed of 3.5 inches of binder under 1.5 inches ! of surface course overlying a scarified and compacted subgrade. 2. In drive areas, 6 inches of asphaltic concrete (4.5 inches of binder under 1.5 inches of surface course) overlying a scarified and compacted subgrade should be adequate. 3. The coarse aggregate in the surface course should be composed of angular crushed limestone rather than smooth gravel. 6.4.2 Portland Cement Pavement If concrete pavement is utilized, the above-recommended procedure for scarification and compaction of the subgrade would also be required. Pavement can then consist of at least 5 inches of adequately reinforced concrete in both parking and drive areas. Theoretically, a thinner pavement section is possible in parking areas; however, to provide adequate concrete cover for reinforcing steel. a 5-inch thick pavement section is required. Concrete pavement joining buildings should be constructed with a curb and the joint between the building and curb should be sealed. Joints in concrete paving should not exceed 15 ft. Calculations used to determine the required pavement thickness are based only on the physical and engineering properties of the materials and conventional thickness determination procedures. Related civil design factors such as , subgrade drainage, shoulder support, cross-sectional configurations, surface .. elevations, reinforcing steel, joint design and environmental factors will significantly affect the service life and must be included in preparation of the construction drawings and specifications, but were not included in the scope of .. this study. Normal periodic maintenance will be required for all pavement to ~ achieve the design life of the pavement system. i . ;, :i I. I ALPHA Report No. 97445 6.4.3 Pavement Specifications Pavement should be specified, constructed and tested to meet the following requirements: 1. Hot Mix Asphaltic Concrete: Texas SDHPT Item 340, Type B Base Course (binder), Type D Surface Course. 2. Portland Cement Concrete: Texas SDHPT Item 360. Specify a minimum compressive strength of 3,000 lbs per sq inch at 28 days. Concrete should be designed with 5 +_ 1 percent entrained air. 3. Re-compacted Subgrada: On-site materials should be scari;:ied to a depth of at least 6 inches and re-compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698) and within the range of 1 percent below to 2 percentage points above the material's optimum moisture content. The moisture content of the subgrade should be maintained until the pavement surface is placed. Density tests should be performed at a frequency of 1 test :, per 5000 sq ft of pavement. 6.5 Drainage Adequate drainage should be provided to reduce seasonal variations in moisture content of foundation soils. All pavement and sidewalks within 10 ft of the " structure should be sloped away from the new building to prevent ponding of water around the foundations. Final grades within 10 ft of the structure should be.. adjusted to slope away from the structure at a minimum slope of 2 percent. Maintaining positive surface drainage throughout the life of the structure is ,, essential. In areas with pavement or sidewalks adjacent to the new structure, a positive seal !i must be maintained between the structure and the pavement or sidewalk to minimize seepage of water into the underlying supporting soils. Post-construction movement of pavement and flat-work is not uncommon. Normal maintenance should include inspection of all joints in paving and sidewalks, etc. as well as re- sealing where necessary. Several factors relate to civil and architectural design and/or maintenance which can significantly affect future movements of the foundation and floor slab system: (1) Where positive surface drainage cannot be achieved by sloping the ground surface adjacent to the building, a complete system of gutters and 11 ALPHA Report No. 97445 downspouts should carry runoff water a minimum of 10 feet from the " completed structure. (2) Large trees and shrubs should not be allowed closer to the foundation than a horizontal distance equal to roughly one-half of their mature height due to their significant moisture demand upon maturing. (3) Moisture conditions should be maintained "constant" around the edge of the slab. Ponding of water in planters, in unpaved areas, and around joints in paving and sidewalks can cause slab movements beyond those predicted in this report. (4) Planter box structures placed adjacent to the building should be provided with a means to assure concentrations of water are not available to the subsoil stratigraphy. i ! (5) Finally, architectural design of the floor slab should avoid additional features such as wing walls as extensions of the slab. Trench backfill for utilities should be properly placed and compacted as outlined in Section 7.3 of this report and in accordance with requirements of local City standards. Since granular bedding backfill is used for most utility lines, the i'i backfilled trench should be prevented from becoming a conduit and allowing an '1 access for surface or subsurface water to travel toward the new structure. Concrete cut-off collars or clay plugs should be provided where utility lines cross building lines to prevent water from travelling in the trench backfill and entering beneath the structure. ,, 7.0 GENERAL CONSTRUCTION PROCEDURES AND RECOMMENDATIONS " Variations in subsurface conditions could be encountered during construction. To permit correlation between test boring data and actual subsurface conditions encountered during construction, it is recommended a registered Geotechnical " Engineer be retained to observe construction procedures and materials. Some construction problems, particularly degree or magnitude, cannot be ,,. anticipated until the course of construction. The recommendations offered in the following paragraphs are intended, not to limit or preclude other conceivable solutions, but rather to provide our observations based on our experience and understanding of the project characteristics and subsurface conditions encountered in the borings. 12 ALPHA Report No. 97445 7.1 Site Preparation and Grading All areas supporting the floor slab and pavement should be properly prepared. After completion of the necessary stripping, clearing, and excavating and prior to placing any required fill, the exposed subgrade should be carefully inspected by probing and testing. Any undesirable material (organic material, wet, soft, or loose soil) still in place should be removed. The exposed subgrade should be further inspected by proof-rolling with either a heavy pneumatic tired roller, loaded dump truck or similar equipment weighing approximately 10 tons to check for pockets of soft or loose material h~dden beneath a thin crust of possibly better soil. Proof-rolling procedures should be observed by the project geotechnical engineer or his representative. Any unsuitable materials exposed should be removed and replaced with well-compacted material as outlined in Section 7.3. Slope stability analysis of embankments (natural or constructed) was not within the scope of this study. Trench excavations should be braced or cut at stable slopes in accordance with Occupational Safety and Health Administration (OSHA) requirements, Title 29, Items 1926.650-1926.653 and other applicable building codes. Due to clayey soils found near the surface, traffic of heavy equipment (including heavy compaction equipment) may create pumping and general deterioration of shallow soils. Therefore, some construction difficulties should be anticipated during periods when these soils are saturated. 7.2 Foundation Excavations All foundation excavations should be monitored to verify foundations' bear on material identified earlier in this report. The bearing stratum exposed in the base of all foundation excavations should be protected against any detrimental change in conditions. Surface runoff water should be drained away from excavations and not allowed to collect. All concrete for foundations should be placed as soon as practical after the excavation is made. Prolonged exposure of the bearing surface to air or water will result in changes in strength and compressibility of the bearing stratum. Therefore, if delays occur, :1 '.i i 13 I ALPHA Report No. 97445 excavations should be slightly deepened and cleaned, in order to provide a fresh bearing surface. All pier shafts should be at least 1.5 ft in diameter to facilitate clean-out of the base and proper monitoring. Concrete placed in pier holes should be directed through a tremie, hopper, or equivalent. Placement of concrete should be vedical through the center of the shaft without hitting the sides of the pier or reinforcement to reduce the possibility of segregation of aggregates. Concrete placed in piers should have a minimum slump of 5 inches to avoid potential honey-combing. Consolidation of concrete with a vibrator should be implemented for concrete with a slump less than 5 inches. Observations during pier drilling should include, but not necessarily be limited to, the following items: Verification of proper bearing strata and consistency of subsurface stratification with regard to boring logs, Confirmation the minimum required penetration into the bearing strata is achieved, Complete removal of cuttings from bottom of pier holes, Proper handling of any observed water seepage and sloughing of subsurface materials, No more than 2 inches of standing water should be permitted in the bottom of pier holes prior to placing concrete, and Verification of pier diameter and steel reinforcement. As shown on the Record of Subsurface Exploration Sheets (re: Borings 1 to 3), highly permeable sand is present at depths between about 4 to 15 ft. Further, groundwater was observed at depths of about 10 to 11 ft. Hence, casing of piers will be required. As casing is extracted, care should be taken to maintain a positive head of plastic concrete and minimize the potential for intrusion of water seepage and sloughing of sand soils. It is recommended a separate bid item be provided for casing on the contractors' bid schedule. 14 ·.-ALPHAReportNo. 97445 7.3 Fill Compaction Materials used as select, non-expansive fill should have a liquid limit less than 35, a plasticity index (PI) not less than about 4 nor greater than 15 and contain no more than 0.5 percent fibrous organic materials, by weight. All select fill should contain no deleterious material and should be compacted to a dry density of at least 95 percent standard Proctor maximum dry density (ASTM D 698) and within the range of 1 percent below to 3 percentage points above the material's optimum moisture content. (Note: The plasticity index and liquid Limit of material used as select, non-expansive fill should be routinely verified during fill placement using laboratory tests. Visual observation and classification should not be relied upon to confirm the material to be used as select, non-expansive fill satisfies the above Atteri.)erg-limit criteria.) Sandy materials with a plasticity index below 25 should be compacted to a dry density of at least 95 percent of standard Proctor maximum dry density (ASTM D 698) and within the range of I percent below to 3 percentage points above the material's optimum moisture content. !i Clay soils with a plasticity index equal to or greater than 25 should be compacted to a dry density between 95 and 100 percent of standard Proctor maximum dry density (ASTM D 698). The compacted moisture content of the clays during should be within the range of 0 to 4 percentage points above optimum. placement 6ClaYinchesfill shoUldprior tobecompaction.Pr°cessed and the largest particle or clod should be less than Limestone or other rock-like materials used as fill should be compacted to at least ,~ 95 percent of standard Proctor maximum dry density. The compacted moisture content of limestone or other rock-like materials is not considered crucial to proper performance. However, if the material's moisture content during placement is within 3 percentage points of optimum, the compactive effort required to achieve the minimum compaction criteria may be minimized. Individual rock pieces larger than 6 inches in dimension should not be used as fill. However, if rock fill is i utilized within 1 ft below the bottom of floor slabs, the maximum allowable size of i individual rock pieces should be reduced to 3 inches. l; In cases where either mass fills or utility lines are more than 10 ft deep, the fill..,' backfill below 10 ft should be compacted to at least 100 percent of standard Proctor maximum dry density (ASTM D-698) and within 2 percentage points of the material's optimum moisture content. The portion of the fill/backfill shallower than 10 ft should be compacted as outlined above. ALPHA Report No. 97445 Compaction should be accomplished by placing fill in about 8-inch thick loose lifts and compacting each lift to at least the specified minimum dry density. Field density and moisture content tests should be performed on each lift as necessary to assure adequate compaction is achieved. As a guide, one test per 2,500 sq ft per lift is recommended in building areas. In larger site areas, a test frequency of one test per 5000 sq ft or greater per lift may be used. Utility trench backfill should be tested at a rate of one test per lift per each 300 lineal feet of trench. 7.4 Groundwater Casing will be required during installation of piers in order to control sloughing of sand soils and water seepage into pier excavations, particularly below about 10 ft. Any other water seepage encountered at shallower depths can be effectively handled by pumping from excavations with pumps or other conventional de- watering equipment. In any areas where significant cuts (2 ft or more) are made to establish final grades for the building pad, attention should be given to possible seasonal water seepage that could occur through natural cracks and fissures in the newly exposed stratigraphy. Subsurface drains may be required to intercept seasonal groundwater seepage. The need for these or other dewatering devices on the building pad should be carefully addressed during construction. Our office could be contacted to visually inspect final pads to evaluate the need such drains. APPENDIX ALPHA Report No. 97445 Ii' A-1 METHODS OF FIELD EXPLORATION Using standard rotary drilling equipment, a total of three (3) test borings have been performed for this geotechnical exploration at the approximate locations shown on the Boring Location Plan, Figure 1. The test boring locations have been staked by the Client. Relatively undisturbed samples of the cohesive subsurface materials have been obtained by hydraulically pressing 3-inch O.D. thin-wall sampling tubes into the underlying soils at selected depths (ASTM D 1587). These samples have been removed from the sampling tubes in the field and examined visually. One representative portion of each sample has been sealed in a plastic bag for use in future visual examinations and possible testing in the laboratory. In addition, representative samples of the subsurface materials have been obtained employing split-spoon sampling procedures in accordance with ASTM Standard D 1586. Disturbed samples have been obtained at selected depths in the borings by driving a standard 2-inch O.D. split-spoon sampler 18 inches into the subsurface material using a 140-pound hammer falling 30 inches. The number of blows required to drive the split-spoon sampler the final 12 inches of penetration (N-value) is recorded in the appropriate column on the Record of Subsurface Exploration sheets. Modified Texas Cone Penetration (TCP) tests have also been completed in the field to determine the apparent in-place strength characteristics of the rock type materials. A 3-inch diameter steel cone driven by a 170-pound hammer dropped 24 inches is the basis for Texas State Department of Highways and Public Transportation strength correlations. In this case, ALPHA TESTING, INC. has modified the procedure allowing the use of a 140-pound hammer dropping 30- inches for completion of the field test. Depending on the resistance (strength) of ,,. the materials, either the number of blows of the hammer required to provide 12 ', inches of penetration, or the inches of penetration of the cone due to 100 blows of the hammer are recorded on the field logs and are shown on the Record of ,.~ Subsurface Exploration sheets as TCP (reference: Texas State Department of Highways and Public Transportation, Bridge Design Manual), using the modified procedure. !i i'. .I ALPHA Report No. 97445 Logs of all borings have been included in the Appendix of this report. The logs show visual descriptions of all soil and rock (shale) strata encountered using the Unified Soil Classification System. Sampling information, pertinent field data, and field observations are also included. Soil and rock (shale) samples not consumed by testing will be retained in our laboratory for at least 30 days and then discarded unless the Client requests otherwise. 18 B-3 · ~ / / /// // ////// -//// / ~ //// / / ,, / / EXISTING A¥~RRTSONS / / / ! BORING LOCATION PLAN SUP~3IIOR SR~{UCI'oqlAL SYST~b~ COPP~.r., TEXAS FIGURE 1 GYMNASTICS ~{ COPPE~.L, TEXAS 97445 6-30-97 ALPHA Report No. 97445 B-1 METHODS OF LABORATORY TESTING Representative samples are inspected and classified by a qualified member of the Geotechnical Division and the boring logs are edited as necessary. To aid in classifying the subsurface materials and to determine the general engineering characteristics, natural moisture content tests (ASTM D 2216), Atterberg-limit tests (ASTM D 4318) and dry unit weight determinations are performed on selected samples. In addition, unconfined compression (ASTM D 2166) and pocket- penetrometer tests are conducted on selected soil samples to evaluate the soil shear strength. Results of all laboratory tests described above are provided on the accompanying Record of Subsurface Exploration sheets or on summary data sheets as noted. ,rc '{ue 'qd. qECORD OF 2209 Wisconsin St ire 100 Dallas, Texas 75229 (972) 620-8911 SUBSURFACE EXPLORATION Chent SUPERIOR STRUCTURAL SYSTEMS Bcr,ng No. B-1 Arch:tect..'Engineer ........................ Jo:; No .......... 97445 Project Name GYMNASTICS CENTER ........ D'a',',,r, 8y . ......... .~A~.. Project Location COPPELL, T__E_X_A.~ ........ Approved B\.- _ ................ __D_A__L_._ DRILLING AND SAMPLING INFORMATION TEST DATA Date Started 6-25-97 Hammer Wt. 140 IDS. Date Compleled 6-25-97 Hammer Drop 30 Dr,il Foreman EDT Spoor] Samp!e OD 2 inspector Rock Core Dia. ~:'.. Bor,ng Methoo CFA Shelby Tobe OD 3 ,n. ,- 2c .---. SOIL CLASSIFICATION ~.~ =~ 'S ~ .... SURFACE ELEVATION ~ ~-,~ ~ ~. ~ ~7-_: ~ ~ ~ ;::~- , ,, Tannish Brown hard S~2~DY CLAY 0 ~ 'CL% zntermixed wisk clay, san~ _- 1 ST 0.6 i6 - and gra-.'el FiLL ........ · 2 i ST 4.5+ 11 LL=22 __ firm wmtk Lncrease in clay -i' - _._ _te ~ ,_ ......................, _ ...... I -.- Tannish Brown rompact S~'.ID (SP) 5 .... , Pi=8 '- wiEh cia'F seams -- 3 , SS 2.6 7 ..... - 5 SS 22 ~ i ]' ' · - wL~h ~ '-race o~ g~ave] below _. i 'J . 5 ' - - - ]E.5' - - Gray SHALE with clay and si]z]' ; ; s~nd seams - I -' '.-' S - BCTTOM CF ?ES7 BOF. Z~,TG :~ ZO' -- ..... 25'--- '- 30 SAMPLER TYPE GROUNDWATER OBSERVATIONS BORING ~ETHOD SS - STANDARD PENETRATION TEST HSA - HOLLO%~ STEM AUGERS ST - SHELBY TUBE AT COMPLETION 10 PT CFA - CONTINUOUS FLIGHT AUGERS CA - CONTINUOUS PLIGHT AUGER AFTER HRS FT. DC - DRIVEN CASINGS HC - ROCK CORE WATER ON RODS !0 FT. MD - MUD DRILLING .c u,t 'rce'ruue ',e. ECORD OF 2209 Wisconsin St., ,',e 100 Dallas, Texas 75229 1972) 620-8911 SUBSURFACE EXPLORATION Ci~ent SUPERIOR STRU_.C__T_URAL SYSTEMS __ B:mng No. . ................. $_-.._2_. Arcnitect/Eng,neer ............................................... Job No. . ........ 97_4._4_5 .......... Project Name GYMNASTICS CENTER Draw" B,,. AM Project Locat~o'- COPPELL, TEXAS Ap::}rs. ve.~ By DAL DRILLING AND SAMPLING INFORMATION TEST DATA Date Started . . ._6-25-97 Hammer Wt. __ _1_~_0 I,.'.'.s Date Comnete,J 6-25-97 Hammer Drop 30 ,r- - DrF,! Foremar' EDI Spoon S~]n]pie OD :::. :: :. ' Inspector Rock Core D a. .,q. Boring Method CFA _ Shelby Tube OD 3 ,n. 5~ - ~ :.:. SOIL CLASSIFICATION -' -- -c ~'5 .................. SURFACE ELEVATION -z ..rd -~ - ~ ~:~ ~f-: u --- .... - ~ ~ ~ ~ ~ ~ ..... ~ ~ ~ ,: Tannish Srown very stiff S~,~DY 2 ~ CLAY 'f]L) intermixe~ with clay, _- ST 2.2 :15 LL=38 - sand and gravel FILL ~ ~PL=15 ..... ~ ' PI=23 · -, . 2 ST 2.0 ~16'. - Tan and Gray very [~f S 'iDY . i ~ CLAY ~CL) , S-- ~ ST 2.5 20iLL=4Z ~ .~ ......... ~ PL=!7 -- Taxnish Nrown very sziff SA2.~DY ..... I - SLAY {r21.; with sanri seams and a -- - ~race oz ~ra',re._ - 5 1'~ - st:_f!f '.-;i~k ::~sr.2ase ---. gravel ~3elsw 13' - 6 Si' . i:_'.: _.3 115 22 I~L=&C .................... ~5 ..... i P~=17 - T~n sc.?.c-acl SZ~,]D ,'S~: wi.~h sor. e :P1:23 _ gr~ve, _ -- ~8' -- Gray SHALE wilh c-av shale -- 2,2. -- - S 'J'Ci6 ' :-- '- -- 25 ........... ~ · ?'~" - BOTTO>{ C,F i'~ST ?2RING :- 25' --- 30 SAMPLER TYPE GROUNDWATER OBSERVATIONS BORING ~ETHOD SS - STANDARD PENETRATION TEST HSA - HOLLOW STEM AUGERS ST - SHELBY TUBE AT COMPLETION 10 FT. CFA - CONTINUOUS FLIGHT AUGERS CA - CONTINUOUS FLIGHT AUGER ACTER HRS. F'I-. DC - DRIVEN CASINGS RC - ROCK CORE WATER ON RODS ~ KT r',.-~D - MUD DRILLING ~_Ptt~ TF_~TINO. lNG. RECORD OF 2209 Wisconsin St. ~:te 100 Dallas, Texas 75225 19721 620-89 SUBSURFACE EXPLORATION Che':: SUPERIOR STRUCTURAL SYSTEMS Bor,n9 No. B-3 Arch,tect.'Engineer __ __ Job No. _ .......... _97445 Prolect Name GYMNASTICS CENTER Drawn By AM Pro;ect Location COPPELL, TEXAS Approved By DAL DRILLING AND SAMPLING INFORMATION TEST DATA Date Started 6-25- 97 Hammer Wt. 140 lbs. Date Completed 6-25-97 Hammer Drop 30 in. -ur_ Drii, Foreman EDI Spoon Sample OD 2 in. Inspector Rock Core Dia. in. Bo-:ng Method CFA Shelby Tube OD 3 __ in. SOIL CLASSIFICATION SURFACE ELEVATION ~: ~ ~ ~ --- Tannish Brown stiff S.~.]D'Z CLAY 0 ~ ~3;L) wish silty sand seams .anl _ - 1 ST 12 - a trace of gravel : -----i _ cla?ey sand ~, 3-4' : 4' - 2 SS - '. - lan and gray kard below 4' .' - - /an dense S~3~ (SP) with cemensed sand seams _ .... 4 SS 3i - - 5 SS 32 - with a trace of gravel ;~e~c;,' - -'- 6 SS 39 seams SAMPLER TYPE GROUNDWATER OBSERVATIONS BORING METHOD SS - STANDARD PENETRAT'.ON TEST HSA - HOLLOW STEM AUGERS AT COMPLETION 10 FT. ST - SHELBY TUBE CFA - CONTINUOUS FLIGHT AUGE.;~S CA - CONI'INUOUS FLIGHI AUGER AFTER HRS.. FT. DC - DRIVEN CASINGS RC - ROCK CORE WATER ON ~ODS 10 FT. MD - MUD DRILLING ALPHA TEE .NG, INC. 2209 Wisconsin SL. Suite 100 Dallas. Texas 75229 (214) 620-8911 KEY TO SOIL SYMBOLS AND CLASSIFICATIONS THE ABBREVIATIONS COMMONLY EMPLOYED ON EACH "RECORD OF SUBSURFACE EXPLORATION", ON THE FIGURES AND IN THE TEXT OF THE REPORT, ARE RS FOLLOWS: SOIL OR ROCK TYPES (SHOWN IN SYMBOLS COLUMN) CLAY S I LT SRND I_ I MESTONE SHALE ASPHALT/CONCRETE I. SOIL DESCRIPTION III RELATIVE PROPORTIONS (A) COHESIONLESS SOILS DESCRIPTIVE TERM PERCENT RELATIUE DENSITY N, BLOWS/FT TRACE 1 - 10 LITTLE 11 - 20 VERY LOOSE 0 TO 4 SOME 21 - 35 LOOSE 5 TO 10 AMD 35 - 50 COMPACT 11 TO 30 DEHSE 31 TO 50 VERY DENSE OUER 50 IU PARTICLE SIZE IDENTIFICATION (B) COHESIUE SOILS BOULDERS: -8 INCH DIAMETER OR MORE CONSISTENCY Ou, TSF COBBLES -3 TO 8 INCH DIAMETER GRAUEL -COARSE - 3/4 TO 3 INCH UERV SOFT LESS THAN 25 -FINE - 5.0 MM TO 3/4 INCH SOFT .25 TO 50 SAND -COARSE - 2.0 MM TO 5.0 MM FIRM .50 TO 1 O0 -MEDIUM - 0.4 MM TO 2.0 MM STIFF 1.00 TO 2 O0 -FINE - 0.07 MM TO 0.4 MM VERY STIFF 2.00 TO 4 O0 SILT -0.002 MM TO 0.07 MM HARD OUER 4 O0 CLAY -0.002 MM II. PLASTICITY U DRILLING AHD SRMPLIHG SYMBOLS DEGREE OF PLASTICITY AU: AUGER SAMPLE PLASTICITY INDEX AC: ROCK CORE TCP: TEXAS COHE PENETRATION TEST NONE TO SLIGHT 0 - 4 SS: SPLIT-SPOON I 3/8" I.D. 2" O.D. SLIGHT 5 - 10 EXCEPT WHERE NOTED MEDIUM 11 - 30 ST: SHELBY TUBE = 3" O.D. EXCEPT HIGH TO VERY HIGH OVER 30 WHERE NOTED WS: WASHED SAMPLE HSR: HOLLOW STEM AUGERS CFR: CONTINUOUS FLIGHT AUGERS HD: MUD DRILLING NOTE: ALL SOILS CLASSIFIED ACCORDING TO THE UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D-2487> CG01083-75