GEOTECHNICAL STUDY NEW CONSTRUCTION AT THE WESTFALL APARTMENTS VISTA DEL SOL DRIVE EL PASO, EL PASO COUNTY, TEXAS

Transcription

1 GEOTECHNICAL STUDY NEW CONSTRUCTION AT THE WESTFALL APARTMENTS VISTA DEL SOL DRIVE EL PASO, EL PASO COUNTY, TEXAS Amec Foster Wheeler Project No Submitted To: 101. S. Jennings Avenue, Suite 100 Fort Worth, Texas Submitted By: Amec Foster Wheeler Environment & Infrastructure, Inc. 125 Montoya Road El Paso, Texas June 6, 2016

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3 TABLE OF CONTENTS REPORT Page Introduction... 1 Proposed Construction... 1 Soil Study... 1 Site Conditions and Geotechnical Profile... 2 Discussion and Recommendations... 4 APPENDIX A Test Drilling Equipment and Procedures... A-1 Unified Soil Classification... A-2 Terminology Used to Describe the Relative Density, Consistency or Firmness of Soil... A-3 Soil Moisture Classification... A-4 Figure 1 Approximate Test Boring Locations... A-5 Logs of Test Borings... A-8 APPENDIX B Classification Test Data... B-1 APPENDIX C Specifications for Earthwork... C-1 Amec Foster Wheeler Project No

4 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (1) 1.0 INTRODUCTION This report is submitted pursuant to a geotechnical study completed by Amec Foster Wheeler Environment & Infrastructure, Inc. (Amec Foster Wheeler) at the Westfall Apartments located at Vista Del Sol Drive in east El Paso, Texas. The objective of this study was to provide recommendations for foundation and pavement design, slab support and related earthwork. 2.0 PROPOSED CONSTRUCTION Mr. Dustin Higgins of RPGA Design Group, Inc. provided details of the project to Amec Foster Wheeler. Mr. Ed Gill of the Housing Authority of the City of El Paso provided the permission to utilize the Preliminary Geotechnical Study for this facility prepared by AMEC Environment & Infrastructure, Inc. (Project No ) dated February 19, 2014 for use on this project. It is our understanding that improvements are planned for the Westfall Apartments located at Vista Del Sol Drive in east El Paso, Texas. We understand that the proposed development will consist of about thirteen (13) one and two story structures totaling about 96 units. We understand that a post-tensioned slab foundation system will be used for the proposed structures. Maximum structural design loads, as conveyed by Ms. Nancy L. Geihl, P.E. with R.L. Woods & Associates, LLC are understood to be 4-kips per linear foot for load bearing walls and 100-kips for column loads. Should final design details vary significantly from those outlined above, this firm should be notified for review and possible modification of recommendations. 3.0 SOIL STUDY 3.1 SUBSURFACE EXPLORATION Two (2) exploratory borings were advanced at the site to a depth of 15 feet below existing grades. Four additional boring drilled to a depth of 20 feet below existing grades were conducted in February 2014 during the previous preliminary study. The test borings were completed using a CME 75 truck-mounted drill rig equipped with 3¼ inch I.D. hollow stem augers. Standard penetration testing was completed at selected intervals in the borings. During the field study, the soils encountered were examined, visually classified and logged. Results of the field study are presented in Appendix A, which includes a brief description of drilling and sampling equipment and procedures, site plans showing the boring locations and logs of the borings. The boring logs and related information included in this report are indicators of subsurface conditions only at the specific locations and times noted. Subsurface conditions at other locations

5 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (2) of the subject site, including groundwater levels, may differ from conditions that were encountered at the locations sampled. 3.2 LABORATORY ANALYSIS To aid in soil classification and evaluate the engineering properties of the soils, selected samples were tested for moisture content, Atterberg Limits and particle size distribution. Laboratory tests were performed in accordance with test standards ASTM D2216, ASTM D4318 and ASTM D422. The results of the moisture testing and Atterberg Limits are shown on the boring logs presented in Appendix A. Atterberg Limits and particle size distributions are presented in Appendix B. Selected samples were also tested with the pocket penetrometer and torvane as a general indication of the undrained shear strength The soils encountered during the field study were classified in general accordance with the Unified Soil Classification System. The soil classification symbols appear on the boring logs and are briefly described in Appendix A. 4.0 SITE CONDITIONS & GEOTECHNICAL PROFILE 4.1 SITE CONDITIONS At present, the subject property is improved with twenty-three two-story apartments, administration building and community center, asphalt paved parking and driving areas, utilities and concrete flatwork. Open areas within the complex consist of landscaping areas with several medium size trees, and playground and basketball court south of the office/community center building. 4.2 GEOTECHNICAL PROFILE The general subsurface conditions encountered during the field exploration conducted May 26, 2016, are shown on the soil boring logs which are included hereafter. The lines of stratification shown on the logs are based upon examination of the recovered soil samples and interpretation of the field boring logs and represent the approximate boundaries between the soil types; the actual transitions may be gradual. As the exploratory borings indicate, the soils underlying the project site generally consists of a nonplastic silty sand that extends from the ground surface to the full depth of the borings. In addition, a slight calcareous induration is present within the soil profile. A poorly graded sand with silt was also encountered at boring B-1 from about 13 feet to 15 feet below the ground surface. Based on standard penetration testing, the soils have a relative density ranging from loose to medium dense.

6 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (3) Soils encountered during this phase of study were observed to be generally similar to conditions encountered during the previous study at the site. The descriptions for relative density and firmness are based on grain size and standard penetration tests as detailed in Terminology Used to Describe the Relative Density, Consistency or Firmness of Soil in Appendix A of this report. 4.3 SOIL MOISTURE AND GROUNDWATER CONDITIONS At the time of our field study, no groundwater was encountered at the boring locations within the explored depths. Soil moisture contents were dry to damp, with values ranging from 2.1 to 11.6 percent. 5.0 DISCUSSION AND RECOMMENDATIONS 5.1 ANALYSIS OF RESULTS Based on the results of our field and laboratory study, the soils encountered at the project site should provide reliable support of the proposed structures following some soil improvements. Following treatment of the soils, the proposed structures may be supported on a post-tensioned flat slab foundation system bearing on structural fill or improved native soils. Recommendations presented in Section 5.4 concerning site drainage and moisture protection are considered critical for the satisfactory performance of the proposed structures. It should be noted that a degree of risk is involved with the use of shallow foundations. Should a broken water line or other source of moisture occur, some movement of foundations is possible. 5.2 POST-TENSIONED SLAB FOUNDATIONS A post-tensioned flat slab foundation system may be used to support the structures provided the site preparation and moisture protection recommendations in this report are followed. The soil conditions encountered at the site do not possess excessive expansion or compressibility properties and a Type II foundation may be utilized. The site has Non-Active Ground Conditions as defined in PTI s Design of Post-Tensioned Slabson-Ground, 3 rd Edition with 2008 Supplement (2008), and bearing capacity for footing design is appropriate. Following the demolition of the existing structures, the recommended site preparation consists of scarifying the native soils to a depth of 12 inches below the base of all foundation elements and floor slabs. The scarified soils should then be brought to within plus or minus 2 percent of the

7 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (4) optimum moisture content and compacted. Structural fill should then be placed, as required, in compacted lifts to final grade. Compaction of the native soils and fill materials should be accomplished by mechanical means to obtain a density of not less than 95 percent of maximum dry density. Optimum moisture content and maximum dry density should be determined in accordance with ASTM D1557. A net allowable bearing pressure ranging from 2,000 pounds per square foot is recommended for the design of foundations bearing on structural fill or improved native soils. The net allowable bearing pressure recommended for each structure applies to full dead plus realistic live loads and can be safely increased by one-third for temporary loads including wind or seismic forces. In order to minimize the sensitivity of the structures to differential movements, slabs should be post-tensioned to allow for a degree of load redistribution should a localized zone of supporting soil become saturated. 5.3 SITE GRADING AND SLAB SUPPORT The recommendations presented above will result in a subgrade preparation that will provide adequate support for a lightly loaded slab-on-grade floor. Thus, the use of granular base for structural support of lightly loaded slabs is not considered necessary. However, a 4-inch course can be placed below the slab to provide a working surface. Heavily loaded slabs cast directly on prepared subgrade should be designed using a modulus of subgrade reaction value of 200 pounds per cubic inch. Where granular base is used, it should meet the following grading requirements as determined by ASTM D422: Sieve Size (Square Openings) 1 inch ¾ inch No. 4 No. 200 Percent Passing by Dry Weight The granular base should have a plasticity index of no greater than 12 when tested in accordance with ASTM D4318. The coarse aggregate should have a percent of wear, when subjected to the Los Angeles abrasion test (ASTM C131), of no greater than 50. Granular base should be compacted to at least 95 percent of ASTM D1557 maximum dry density. Granular base will tend to act as a capillary barrier to moisture but does not provide a positive barrier against the rise of moisture to the slab. If the moisture sensitivity of floor coverings is considered critical, an impervious membrane vapor barrier should be placed beneath the floor slab.

8 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (5) 5.4 SITE DRAINAGE AND MOISTURE PROTECTION Moisture increases in the soils supporting foundations would reduce their support value and increase movements. Therefore, positive site drainage should be provided during construction and carefully maintained for the life of the structures. Where slabs or pavements do not immediately adjoin the structures, the ground surface should be sloped away from the perimeter in a manner to allow flow along the drainage lines at a minimum grade of 5 percent to points at least 15 feet away. Positive drainage should be provided from these points to streets, natural water courses or proposed ponding areas. Long-term ponding of water should never be allowed around the perimeter of the planned structures. Landscaped areas should not be allowed immediately adjacent to the planned structures unless contained in water tight boxes or constructed with a controlled outlet. All landscaping near the structures should consist of short rooted, desert type plants requiring little or no watering. Irrigation drip systems near the structures, particularly in areas underlain by impervious membrane, should be avoided. Roof drains should be designed and constructed to discharge storm water directly onto paved areas that will carry the water rapidly away from the buildings. No storm water from roof drains should be allowed to discharge onto or accumulate in unpaved areas close to the structures. The possibility of moisture infiltration beneath the structures, in case of plumbing leaks, should be considered in the design and inspection of underground water and sewer conduits. All backfill behind footings and stem walls, as well as utility trench backfill within 15 feet of the structures, should be compacted as recommended for structural fill in Appendix C. 5.5 LATERAL LOADS The pressure exerted on retaining walls will depend on their degree of restraint. Rigid, restrained walls with horizontal backfill meeting structural fill requirements as presented in Appendix C of the geotechnical report, should be designed using an "at rest" equivalent fluid pressure of 60 pounds per cubic foot (pcf). Walls allowed to rotate around their bases at a distance of times their height or more, at the top, should be designed using an "active" equivalent fluid pressure of 40 pcf. The passive soil resistance against the edges of footings, stem walls, etc. with properly compacted backfill, should be considered as being equal to forces exerted by a fluid of 350 pounds per cubic foot unit weight. A coefficient of friction (f) of may be used in calculations for sliding purposes between the base of the footing and soil. The equivalent fluid pressures do not include any lateral component due to either hydrostatic or surcharge loads. The retaining walls at this site should be designed with a drainage system to prevent the buildup of hydrostatic forces behind the wall. If a drain system is not provided, then an additional 62.4 pcf must be added to the lateral forces acting on the wall. Special care should

9 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (6) be taken not to over compact the backfill material to reduce the potential for the buildup of residual compaction pressures against the retaining walls. The equivalent fluid pressures provided above do not include a factor of safety, however, we recommend that a minimum factor of safety of 1.5 be used for the design of retaining walls against overturning and sliding. Surcharge loads, such as vehicular wheel loads, to the area adjacent to the retaining wall can add additional horizontal components of lateral earth pressures to this wall. The magnitude of these components will depend on the loads and locations of these loads relative to the retaining wall. 5.6 PAVEMENT RECOMMENDATIONS FLEXIBLE PAVEMENT The soils encountered correlate to an A-2-4 classification in accordance with the American Association for State Highway and Transportation Officials (AASHTO) Standard M-145, and are considered good for use as subgrade support. The majority of the improvement is understood to be primarily for light passenger vehicle parking; the recommended section for such areas is a Light-Duty Flexible Section. Drive Lanes that are to be subjected to usage by heavier vehicles, such as delivery trucks and fire lanes, are recommended to be constructed with a Medium Duty Flexible Section. A rigid pavement section is recommended in areas of waste disposal receptacles and the pavement section for the accommodation of such should extend out a sufficient distance to accommodate the entire length of the waste disposal vehicle itself. Following the proper treatment of the subgrade, the following flexible pavement sections are recommended:

10 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (7) Flexible Pavement Component Pavement Component Thickness (inches) Light-Duty Medium-Duty Hot-Mix Asphaltic-Concrete (HMAC), Grade C (Surface Course) 2 3 Aggregate Base Course (ABC) 5 6 Existing Subgrade The recommended subgrade preparation should consist of scarifying the native soil to a depth of 12 inches. The scarified soil should then be brought to within plus or minus 2 percent of optimum moisture content and compacted. The pavement areas should then be brought to final subgrade elevation with properly compacted structural fill as determined by drainage considerations and pavement thickness. Structural fill should be non-expansive and meet specifications as outlined in Appendix C of this geotechnical report. Aggregate base course should conform with the requirements of Type A, Grade 1 or 2 of Item 247 of the Texas Department of Highways and Public Transportation Standard Specifications for Construction of Highways, Streets, and Bridges. Asphaltic concrete materials quality and construction requirements should conform to Division III of the current Texas Department of Highways and Public Transportation Standard Specification for Construction of Highways, Streets, and Bridges. Mineral aggregate should comply with Type C, Item A job mix formula should be established using the Marshall method of mix design which has a minimum stability of 1600 pounds as determined in accordance with ASTM D1559. The bituminous material and aggregate proposed for use in construction by the contractor should be used in the mix design RIGID PAVEMENT For paved areas subjected to heavy truck traffic or service vehicles with regular stopping, starting or turning actions and at dumpster storage areas a rigid pavement section is recommended in lieu of a flexible pavement. Recommendations provided above for subgrade preparation should be followed prior to the construction of the rigid pavement section. These recommendations will result in a subgrade preparation that will provide adequate support for the rigid pavement section. The concrete to be used in construction was assumed to have an elastic modulus of 3.8x10 6 psi and a mean modulus of rupture of 650 psi. This would generally correspond to a 28-day cylinder strength of 4,400 psi as determined in accordance with ASTM C39. A working stress of 60,000 psi (corresponding to Grade 60) was assumed for the reinforcing steel. All materials and methodologies used in construction should conform with guidelines presented in "Item 360-Concrete Pavement" section of the current edition of the Texas Department for Construction of Highways, Streets and Bridges. Based on the above design parameters and

11 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (8) guidelines provided by AASHTO (19 93), a 6-inch concrete pavement overlying 6 inches of aggregate base course is recommended. It is recommended the concrete slab is constructed to allow rapid drainage of surface runoff away from the soil directly underlying the pavement section. 5.7 CONSTRUCTION OBSERVATION AND TESTING Recommendations presented in previous sections of this report are predicated on the assumption that there will be continuous observation and testing by the geotechnical engineer during earthwork operations. Verification of recommended moisture increases, excavations and required degree of compaction should be performed in accordance with "Guide Specifications for Earthwork," Appendix C. The recommendations presented in this report are based upon a limited number of subsurface samples obtained from a total of six sampling locations. The samples may not fully indicate the nature and extent of the variations that actually exist between sampling locations. For that reason, among others, Amec Foster Wheeler recommends that Amec Foster Wheeler be retained to observe earthwork construction. It should be noted if variations or other latent conditions become evident during earthwork construction, it will be necessary for Amec Foster Wheeler to review these conditions and modify its recommendations.

12 APPENDIX A

13 TEST DRILLING EQUIPMENT & PROCEDURES SAMPLING PROCEDURES - Dynamically driven tube samples are usually obtained at selected intervals in the borings by the ASTM D-1586 procedures. In most cases, 2" O.D.samplers are used to obtain the standard penetration resistance. Undisturbed samples of firmer soil are often obtained with 3" O.D. samplers lined with 2.42" I.D. brass rings. The driving energy is generally recorded as the number of blows of a 140 pound, 30-inch free fall drop hammer required to advance the samplers in 6-inch increments. However, in stratified soil, driving resistance is sometimes recorded in 2 or 3-inch increments so that soil changes and the presence of scattered gravel or cemented layers can be readily detected and the realistic penetration values obtained for consideration in design. These values are expressed in blows per foot on the logs. Undisturbed sampling of softer soil is sometimes performed with thin walled Shelby tubes (ASTM D-1587). Where samples of rock are required, they are obtained in NX diamond core drilling (ASTM D-2113). Tube samples are labeled and placed in watertight containers to maintain field moisture contents for testing. When necessary for testing, larger bulk samples are taken from auger cuttings. CONTINUOUS PENETRATION TESTS - Continuous penetration tests are performed by driving a 2" O.D. blunt nosed penetrometer adjacent to or in the bottom of borings. The penetrometer is attached to 1-inch O.D. drill rods to provide clearance to minimize side friction so that penetration values are recorded as the number of blows of a 140 pound, 30-inch free fall drop hammer required to advance the penetrometer in one foot increments or less. BORING RECORDS - Drilling operations are directed by our field engineer or geologist who examines soil recovery and prepares boring logs. Soil is visually classified in accordance with the Unified Soil Classification System (ASTM D-2487), with appropriate group symbols being shown on the logs.

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15 TERMINOLOGY USED TO DESCRIBE THE RELATIVE DENSITY CONSISTENCY, OR FIRMNESS OF SOIL The terminology used on the boring logs to describe the relative density, consistency or firmness of soil relative to the standard penetration resistance is presented below. The standard penetration resistance (N) in blow per foot is obtained by ASTM D-1586 procedure using 2" O.D., 1-inch I.D. samplers. RELATIVE DENSITY: Terms for description of relative density of cohesionless, uncemented sand and sand-gravel mixtures. N RELATIVE DENSITY Very Loose Loose Medium Dense Dense Very Dense RELATIVE CONSISTENCY: Terms for the description of clay which is saturated or near saturation. N RELATIVE CONSISTENCY REMARKS Very Soft Soft Medium Stiff Stiff Very Stiff Hard Easily penetrated several inches with fist. Easily penetrated several inches with thumb. Can be penetrated several inches with thumb moderate effort. Readily indented with thumb but penetrated only with great effort. Readily indented with thumbnail. Indented only with difficulty by thumbnail. RELATIVE FIRMNESS: Terms for the descriptions of partially saturated and/or cemented soil which commonly occurs in the Southwest including clay, cemented granular materials, silt and silty and clayey granular soil: N RELATIVE DENSITY Very Soft Soft Moderately Firm Firm Very Firm Hard

16 SOIL MOISTURE CLASSIFICATION ESTIMATED RANGE OF MOISTURE MOISTURE CONDITION FIELD IDENTIFICATION Group A (%) Group B (%) Dry Absence of moisture, dusty. Dry to the touch Damp Moist Wet Grains appear slightly darkened, but no visible water. Silt/clay may clump. Sand will not bulk. Soils are below plastic limits. Grains appear darkened, but no visible water. Silt/clay will clump. Sand will bulk. Soils are often at or near plastic limits. Visible water on larger grain surfaces. Sand and cohesionless silt exhibit dilatancy. Cohesive silt/clay can be readily remolded. Wet indicates that the soil is much wetter than the optimum moisture content and above the plastic limit (APL) >16 >30 Water Bearing A water-producing formation. N/A N/A Group A - Coarse Grained Soils, nonplastic to plasticity index <7. Includes: SM, SP-SM, SP, SW, GM, GP, and GW. Group B - Fine Grained Soils to clayey sands & gravels with a plasticity index >7. Includes: GC, SC, ML, MH, CL, and CH.

17 PB-1 PB-2 PB-3 B-1 B-2 PB-4 CLIENT: AMEC FOSTER WHEELER Environment & Infrastructure 125 Montoya, El Paso, Texas LEGEND Approximate Boring Location B-1 Boring ID PB-1 Previous Boring ID DWN BY: JT CHK'D BY: MB DATUM: N/A PROJECTION: N/A SCALE: NTS PROJECT: TITLE: REV. NO.: GEOTECHNICAL STUDY 0 Westfall Apartments DATE: El Paso, El Paso County, Texas 5/27/2016 APPROXIMATE BORING LOCATION MAP PROJECT NO: CONTRACT NO: N/A FIGURE NO: 1

18 PROJECT JOB NO. Depth in Feet Continuous Penetration Resistance New Construction at the Westfall Apartments Vista Del Sol Drive El Paso, El Paso County, Texas Graphical Log Sample Sample Type DATE Blows Per Six Inches 5/26/16 SPT N-Value Moisture Content Percent of Dry Weight Percent Fines Liquid Limit Plastic Limit Plasticity Index Unified Soil Classification or Rock Unit LOCATION RIG TYPE BORING TYPE SURFACE ELEV. DATUM REMARKS Environment & Infrastructure, Inc. 125 Montoya Road El Paso, TX Telephone: See Site Plan CME 75 Hollow Stem Auger Method Existing Ground Surface VISUAL CLASSIFICATION 0 S SM Desne PP=1.0 tsf 2" HMAC over 4" Aggregate Base Course Silty Sand - Reddish brown medium and fine SAND, little silt, nonplastic fines, few gravel, subangular to subrounded, dry. S SM Medium Dense PP=0.75 tsf Silty Sand - Reddish brown medium and fine SAND, little silt, nonplastic fines, trace gravel (cemented sands, caliche), damp. 5 S Loose S Loose 10 S Medium Dense 15 S SP-SM Dense Poorly Graded Sand with Silt - Reddish brown medium and fine SAND, few silt, nonplastic fines, trace gravel, subrounded to subangular, damp. Auger terminated at 15 feet. Sampler terminated at 16.5 feet. PP - Pocket Penetrometer tsf - tons per square foot GROUNDWATER DEPTH(ft) HOUR DATE NE 5/26/2016 SAMPLE TYPE A - Drill cuttings S - 2" O.D. 1.38" I.D. tube sample U - 3" O.D. 2.42" I.D. tube sample C - 3" O.D. CME tube sample SH - 3" Shelby sample NR - No Recovery NE - Not Encountered LOG OF TEST BORING NO. Page B-1 1 of 1

19 PROJECT JOB NO. Depth in Feet Continuous Penetration Resistance New Construction at the Westfall Apartments Vista Del Sol Drive El Paso, El Paso County, Texas Graphical Log Sample Sample Type DATE Blows Per Six Inches 5/26/16 SPT N-Value Moisture Content Percent of Dry Weight Percent Fines Liquid Limit Plastic Limit Plasticity Index Unified Soil Classification or Rock Unit LOCATION RIG TYPE BORING TYPE SURFACE ELEV. DATUM REMARKS Environment & Infrastructure, Inc. 125 Montoya Road El Paso, TX Telephone: See Site Plan CME 75 Hollow Stem Auger Method Existing Ground Surface VISUAL CLASSIFICATION 0 S SM Medium Dense 2" HMAC over 4" Aggregate Base Course Silty Sand - Reddish brown medium and fine SAND, little silt, nonplastic fines, trace to few gravel, subangular to subrounded, dry to damp. S Loose 5 S NV --- NP SM Loose Silty Sand - Reddish brown medium and fine SAND, some silt, nonplastic fines, trace gravel (cemented sands, caliche), damp. S SM Loose Silty Sand - Brown medium and fine SAND, little silt, nonplastic fines, trace gravel, subrounded to subangular, damp. 10 S Medium Dense 15 S Medium Dense Auger terminated at 15 feet. Sampler terminated at 16.5 feet. 20 S GROUNDWATER DEPTH(ft) HOUR DATE NE 5/26/2016 SAMPLE TYPE A - Drill cuttings S - 2" O.D. 1.38" I.D. tube sample U - 3" O.D. 2.42" I.D. tube sample C - 3" O.D. CME tube sample SH - 3" Shelby sample NR - No Recovery NE - Not Encountered LOG OF TEST BORING NO. Page B-2 1 of 1

20 APPENDIX B

21 TABULATION OF TEST RESULTS DATE: May 2016 Amec Foster Wheeler Job No.: PROJECT: New Construction at the Westfall Apartments Vista Del Sol Drive El Paso, El Paso County, Texas BORING NO. LOCATION DEPTH UNIFIED CLASS. LL PL PI SIEVE ANALYSIS - ACCUM. % PASSING No.200 No.100 No.40 No.10 No.4 ⅜ ½ ¾ 1 1¼ 1½ 3 MOISTURE % B1 See Site Plan 0-1½ SM B1 See Site Plan 15-16½ SP-SM B2 See Site Plan 5-6½ SM NV --- NP NV No Value NP Nonplastic

22 APPENDIX C

23 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (C-1) 1. SCOPE GUIDE SPECIFICATIONS FOR EARTHWORK Includes all clearing and grubbing, removal of obstructions, general excavating, grading and filling and any related items necessary to complete the grading for the entire project in accordance with these specifications. 2. SUBSURFACE SOIL DATA Subsurface soil studies have been made and the results are available for examination by the contractor. The contractor is expected to examine the site and determine for himself the character of materials to be encountered. No additional allowance will be made for rock removal, site clearing and grading, filling, compaction, disposal or removal of any unclassified materials. 3. CLEARING AND GRUBBING A. General: Clearing and grubbing will be required for all areas shown on the plans to be excavated or on which fill is to be constructed. B. Clearing: Clearing shall consist of removal and disposal of vegetation, existing structures, foundation, slab and utilities present on the site. C. Grubbing: Stumps, matted roots and roots larger than 2 inches in diameter shall be removed from within 6 inches of the surface of areas on which fills are to be constructed except in roadways. Materials as described above within 18 inches of finished subgrade in either cut or fill sections shall be removed. Areas disturbed by grubbing will be filled as specified hereinafter for STRUCTURAL FILL. 4. EARTH EXCAVATION A. Earth excavation shall consist of the excavation and removal of suitable soil for use as embankment as well as the satisfactory disposal of all vegetation, debris and deleterious materials encountered within the area to be graded and/or in a borrow area. B. Excavated areas shall be continuously maintained such that the surface shall be smooth and have sufficient slope to allow water to drain from the surface.

24 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (C-2) 5. STRUCTURAL FILL A. General: Structural fill shall consist of a controlled fill constructed in areas indicated on the grading plans. B. Materials: (1) Physical Characteristics: Structural fill material shall consist of soil that conforms to the following physical characteristics: Sieve Size Percent Passing (Square Openings) by Weight 3 inch 100 3/4 inch No No The plasticity index of the material, as determined in accordance with ASTM D4318, shall not exceed 15. The fill material shall be free from roots, grass, other vegetable matter, clay lumps, rocks larger than 3 inches in any dimension, or other deleterious materials. (2) Site Soil: Site soil from cuts may be used for fill, provided they meet the requirements in paragraph 5.B.(1). The results of this soil study indicate that the majority of the soils encountered at the site will meet the requirements for structural fill. (3) Borrow: When the quantity of suitable material required for embankments is not available within the limits of the jobsite, the contractor shall provide sufficient materials to construct the embankments to the lines, elevations and cross sections as shown on the drawings from borrow areas. The contractor shall obtain from owners of said borrow areas the right to excavate material, shall pay all royalties and other charges involved, and shall pay all expenses in developing the source including the cost of right-of-way required for hauling the material. C. Construction: (1) Building Area Treatment: The building pad shall be inspected by a representative of the geotechnical engineer prior to fill placement to verify clearing and grubbing. Site preparation shall consist of scarifying the native soils to a depth of 12 inches. The scarified soils shall then be brought to within plus or minus 2 percent of the optimum moisture content and compacted. Structural fill shall then be placed, as required, in compacted lifts to final grade.

25 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (C-3) (2) Slabs on Grade Treatment: Below slabs on grade, the recommended site preparation consists of scarifying the native soils to a depth of 12 inches. The scarified soils shall then be brought to within plus or minus 2 percent of optimum moisture content and compacted. Structural fill should then be placed, as required, in compacted lifts to final grade. (3) Pavement Section: Prior to construction of a pavement section, the existing subgrade shall be scarified to a depth of 12 inches, brought to within plus or minus 2 percent of optimum moisture content and compacted. The parking and driving areas shall then be brought to final subgrade elevation with properly compacted structural fill as determined by drainage considerations and pavement thickness. (4) Compaction: All fill shall be spread in layers not exceeding 8 inches, watered as necessary, and compacted. Moisture content at the time of compaction shall be within plus or minus 2 percent of the optimum moisture content. Compaction of the fill shall be accomplished by mechanical means only to obtain a density of not less than 95 percent of maximum dry density for the building pad, paved areas, and other structural areas. Embankments outside the building pads shall be compacted to 90 percent of maximum dry density. Optimum moisture content and maximum dry density for each soil type used shall be determined in accordance with ASTM D1557. Where vibratory compaction equipment is used, it shall be the contractor's responsibility to insure that the vibrations do not damage nearby buildings or other adjacent property. (5) Weather Limitations: Controlled fill shall not be constructed when the atmospheric temperature is below 35 degrees F. When the temperature falls below 35 degrees, it shall be the responsibility of the contractor to protect all areas of completed surface against any detrimental effects of ground freezing by methods approved by the geotechnical engineer. Any areas that are damaged by freezing shall be reconditioned, reshaped and compacted by the contractor in conformance with the requirements of this specification without additional cost to the owner. D. Slope Protection & Drainage: The edges of the controlled fill embankments shall be graded to the contours shown on the drawings and compacted to the density required in paragraph 5.C.(4). Slopes steeper than 1 vertical to 3 horizontal shall be protected from erosion. 6. INSPECTION & TESTS A. Field Inspection & Testing: The owner shall employ the services of a registered, licensed geotechnical engineer for consultation during all controlled earthwork operations. The geotechnical engineer shall provide continuous on-site observation and testing services during controlled earthwork activities. The contractor shall notify the engineer at

26 RPGA Design Group, Inc. Geotechnical Study New Construction at Westfall Apartments Amec Foster Wheeler Job No Page (C-4) least two working days in advance of any field operations of the controlled earthwork, or of any resumption of operations after stoppages. Tests of fill materials and embankments will be made at the following suggested minimum rates: (1) One field density test in the building area for each 2,500 square feet of original ground surface prior to placing fill. (2) One field density test in the building area for each 2,500 square feet of fill placed or each layer of fill for each work area, whichever is the greater number of tests. (3) One field density test in pavement areas for each 5,000 square feet of fill placed or each layer of fill for each work area, whichever is the greater number of tests. (4) One moisture-density curve for each type of material used, as indicated by sieve analysis and plasticity index. B. Report of Field Density Tests: The geotechnical engineer shall submit, daily, the results of field density tests required by these specifications. C. Costs of Tests & Inspection: The costs of tests, inspection and engineering, as specified in this section of the specifications, shall be borne by the owner.