GEOTECHNICAL/GEOPHYSICAL INVESTIGATION

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2 GEOTECHNICAL/GEOPHYSICAL INVESTIGATION at PROPOSED GLASS RESIDENCE HOUSTON, TEXAS Prepared for Mr. Joe Glass 9215 Hilldale Houston, TX by BRYANT CONSULTANTS, INC. GEOTECHNICAL AND FORENSIC ENGINEERING CONSULTANTS CARROLLTON, TX BCI Report No April 26, 2004

3 TABLE OF CONTENTS PROJECT INFORMATION 1 SCOPE OF INVESTIGATION 1 FIELD OPERATIONS 1 LABORATORY TESTING 2 EVALUATION OF SITE INFORMATION 3 SUBSURFACE CONDITIONS 5 ELECTRICAL RESISTIVETY PROFILES 9 ANALYSIS AND RECOMMENDATIONS 12 EARTHWORK GUIDELINES 22 LIMITATIONS AND REPRODUCTIONS 25 FIGURES GMMIR Profile and Boring Location Plan 1 Tree Survey 2 GIS Map of Site 3 Logs of Boring B-1 4 Logs of Boring B-2 5 Moisture Content Profile 6 Hand Penetrometer Profile 7 Total Soil Suction Profile 8 Liquidity Index Profile 9 Swell Test Results 10 GMMIR Profile R1 11 Photographic Survey of Site 12 Rainfall Data for Houston Hobby 13 E Log P Curve 14 Boring Log Legend 15 APPENDIX 1 GUIDELINES FOR THE PLACEMENT OF CONTROLLED EARTHWORK

4 GEOTECHNICAL/GEOPHYSICAL INVESTIGATION for PROPOSED GLASS RESIDENCE HOUSTON, TEXAS A. PROJECT INFORMATION BCI understands the proposed residence will be located at 9221 Elizabeth Road in Houston, Texas. It is our understanding the proposed construction will consist of a multiple story, single family dwelling. Final grades for the proposed residence were unavailable for our review. However, for this report, we assume that the proposed pad will be constructed within 18 inches of the existing grades. If cuts and/or fills exceed this assumption, then BCI should be contacted in order to determine if the recommendations in this report are still valid. No specific warranty program or other standards, except acceptable industry standards, were followed in this investigation. B. SCOPE OF INVESTIGATION The purposes of the study are to: 1) explore the general subsurface conditions at the site, 2) evaluate the pertinent engineering properties of the subsurface materials, 3) perform one Geo-electrical Moisture Material Imaging and Resistivity (GMMIR) profile and two geotechnical borings at this site and 4) provide recommendations and design parameters concerning suitable types of foundation systems. C. FIELD OPERATIONS I. Geotechnical Exploration Two geotechnical borings were performed on March 17, The borings were drilled at the approximate locations shown on Figure 1 GMMIR Profile and Boring Location Plan. A continuous flight auger drilling rig was used to advance the borings to a depth of 25 to 30 feet below grade. Undisturbed specimens of cohesive soils were obtained at intermittent intervals with nominal 3-inch diameter thin-walled, seamless tube samplers. Disturbed

5 Proposed Glass Residence Page 2 samples were also retrieved using augering techniques. These specimens were extruded in the field, logged, sealed and packaged to help protect them from disturbance and to help maintain their in-situ moisture content during transportation to our laboratory. Figures 4 and 5 present descriptions of the soil properties and Figures 6 to 10 present a summary of the laboratory data. II. Geophysical Exploration In conjunction with the geotechnical borings, some additional information regarding the location of moisture and material differences around the perimeter of the structure was obtained using the geo-electrical moisture/material imaging method (GMMIR). Two geo-electrical (electrical resistivity) profiles were originally performed at the location of the proposed residence. However, equipment malfunction result in errant data from one of the profile and therefore will not be included in this report. Profile R1 was taken across the residential lot to characterize the conditions of the soils and the resistivity structure beneath the surface as presented on Figure 1. Measurements of the field resistivity were performed in general accordance with ASTM G-57 with modifications of the electrode configuration. Figure 11 provides a depth profile of GMMIR Profile R1 geo-electrical resistivity model. III. Benchmark Installation After drilling operations were complete in Boring B-1, BCI installed a benchmark. The bearing end of the benchmark was approximately 35 feet below grade. D. LABORATORY TESTING Samples were examined at our laboratory by the project geotechnical engineer. Selected samples were subjected to laboratory tests under the supervision of this engineer. A brief discussion of these results is provided below. The dry unit weights, moisture contents, liquid and plastic limits of the selected soil samples were measured. These tests were used to evaluate the potential

6 Proposed Glass Residence Page 3 volume change of the different strata as an indication of the uniformity of the material and to aid in soil classification. To provide additional information about the swell characteristics and evaluate volume change characteristics of these soils (at their in-situ moisture conditions) total soil suction tests and absorption swell tests were performed on selected samples of the clay soils. Unconfined compression and hand penetrometer tests were also performed on selected undisturbed samples of the clay soils. These tests were performed to evaluate the strength and consistency of these materials. Consolidation properties of one soil sample were obtained by performing onedimensional consolidation tests. A consolidation test was performed on a soil sample retrieved from Boring B-1 at a depth between six to seven feet below grade. The void ratio pressure curve (e log p curve) for this soil sample is located in Figure 14. E. EVALUATION OF SITE INFORMATION Based on information received from Mr. Ron Kelm, P.E. with Forensic Engineers, Inc., the residential lot is approximately 115 feet wide and 330 feet long. The residential pad is approximately 80 by 80 feet. The approximate location of the residential pad with respect to the lot is reproduced in Figures 1 and 2. A rather large drainage ditch borders the south perimeter of the residential lot. The proposed foundation system is reportedly to be construction approximately 4 to 5 feet above existing ground level. I. General Soil/Geologic Conditions The property is located at 9221 Elizabeth Road in Houston, Texas. Based on the Geologic Atlas of Texas and our experience in the local vicinity, the site is situated within the Beaumont Formation. The Beaumont Formation typically consists of surficial clay and mud of low permeability, high compressibility, high to very high shrink/swell capacity, low shear strength and high plasticity. Based upon the USDA Harris County Soil Survey, this site is situated on the Addicks-Urban land complex. The following information is based upon the USDA

7 Proposed Glass Residence Page 4 Harris County soil survey, and should be considered generally indicative of the type of soils and the range of engineering properties noted for this area and at this site, and should be used only as an indicator of the soil properties at this site. The surface of the Addicks-Urban land complex is plane to slightly convex with 0 to 1 percent slopes. This surface layer of the Addicks soil is friable, black loam about 11 inches thick. The next layer is friable, dark gray loam approximately 12 inches thick. Friable, dark gray loam with calcium carbonate and yellow to yellowish brown mottles is typically encountered at depth. This soil is poorly drained. Surface runoff is slow and permeability is moderate. The available water capacity is high. It is saturated with water for short periods during the year. The liquid limits and plasticity indices for this soil group ranges between 20-45% and 5-27%, respectively; the shrink-swell potential for the soil group, therefore, is low to moderate. II. Site Grading and Drainage Based upon visual observations and geotechnical exploration, no significant amounts of cut or fill were detected at this site at the time of our investigation. Boring B-2 encountered approximately 6 inches of fill sand. Figure 12 provides two photographs of general site information. As shown in Figure 12, the residential property is currently flat with no significant change in topography. For a more detailed description of the site grades, please refer to a limited topography map of the site performed by Godinich Surveyor s, LLC. III. Tree Survey Numerous mature trees are present within the residential lot. Figure 12 pictures the approximate size of these trees. Figure 2 Tree Survey provides the approximate location of the documented tree trunks within the residential lot. As shown in Figure 2, a few trees may be removed during construction of the residential structure. Figure 3 GIS Map of Site also provides an aerial view of the residential lot and house pad. As shown in Figure 3, the tree canopies generally cover the majority of the residential lot. Also, a pre-existing structure may have been present during this aerial photograph; however, the structure was not present during our investigation.

8 Proposed Glass Residence Page 5 IV. Rainfall Data Figure 13 plots the monthly rainfall totals since 1998 at the National Weather Service (NWS) Houston/Galveston station located at the Hobby Airport. Monthly rainfall averages include observation recordings at the Hobby Airport, which is south of this residential structure. Rainfall totals and averages are based on the NOAA, NWS Web Site for the Hobby Airport area. Based on Figure 13, monthly rainfall totals during 1999 and 2001 are most likely considered rainfall extremes. As shown in Figure 13, yearly rainfall totals in 1999 and 2000 were comparatively below the yearly average. The majority of 1999 was considerably dry, particularly during the late summer and fall months, as indicated in Figure 13. A considerable amount of rainfall was recorded during June 2001 and August The year 2001 recorded approximately 30 inches of rainfall above the yearly average. Monthly rainfall totals were below average in January and February However, the monthly rainfall totals of 2002 were also well above the average, particularly for the months of July, August and October. The year 2002 recorded approximately 8 inches of rainfall above the yearly average. The year 2003 recorded approximately 5 inches of rainfall below the yearly average. However, during our site investigation, the months of January and February 2004 have been above the monthly average. Therefore, BCI concludes that our geotechnical/geophysical investigation in March 2004 was conducted during a relatively wet climatic period. F. SUBSURFACE CONDITIONS The subsurface conditions encountered in the borings are presented in Figures 4 and 5. Descriptions of the various strata and their approximate depths and thickness are shown in the Logs of Borings. A brief summary of the general stratigraphy indicated by the borings is given below. Depth refers to depth from the ground surface existing at the time of this investigation. References to depth should be made from this datum. I. Soil Stratigraphy Based upon site observations and the geotechnical borings, BCI is of the opinion that observed soil conditions are similar to those identified in the published geologic and soil information mentioned previously. In addition, Boring B-1

9 Proposed Glass Residence Page 6 encountered sandy fill soils in the upper six inches. The following paragraph provides a brief summary of the soils encountered within the geotechnical borings. For a more detailed description of the soils encountered, refer to the attached boring logs. The geotechnical borings generally encountered olive black, dark yellowish brown, to brownish black sandy lean clay to clayey sand. Light olive gray, dark yellowish brown to brownish gray lean clay with sand to sandy lean clay typically followed. A grayish orange, pale yellowish brown to yellowish gray lean clay with sand stratum was encountered next. At approximately 13 feet below grade, yellowish gray, light gray to grayish orange sandy lean clay was encountered in both borings. Boring B-2 encountered moderate yellowish brown, yellowish gray to grayish orange sandy lean clay beginning approximately 21 feet below grade. II. Water Observations The borings were advanced using a continuous flight auger. These drilling procedures allow groundwater seepage to be observed during and after drilling. Water seepage was observed at approximately 17 and 22 feet below grade during drilling operations for Borings B-1 and B-2, respectively. The water level remained constant in Boring B-2 after drilling operations. The bore hole caved in at 17 feet after drilling operations ceased in Boring B-1. The driller s log for Boring B-1 described the soil conditions below 20 feet as flowing sands. The water levels may fluctuate at this site due to perennial rainfall totals and/or perched water seepage. III. Analysis of Geotechnical Borings a. Moisture Content Moisture content is defined as the ratio of the weight of water to the weight of dry soil in a given sample volume. Moisture content values are continuously recorded for every foot of soil. Figure 6 plots the moisture content profile for each geotechnical boring. As shown in Figure 6, the moisture contents ranged between 11 and 26 percent.

10 Proposed Glass Residence Page 7 b. Consistency and Strength Tests BCI performed two test methods to further evaluate the strength and consistency of the retrieved soil samples. Hand penetrometers are used to measure the resistance to penetration of a soil. Typical hand penetrometer values range between 1.0 tons per square foot (tsf) and 4.5 tsf, with 4.5 tsf being the largest value able to be recorded on instrument. Figure 7 plots the hand penetrometer values for each geotechnical boring. The other test method is the unconfined compression test. This test is a special type of unconsolidated-undrained test commonly used for clayey type soils. Unconfined compressive strength tests provide a more accurate determination of the soil strength and consistency in comparison to the hand penetrometer values. The results of both these tests are located in the boring logs. The unconfined compressive strength values ranged between 1008 pounds per square foot (psf) and 4889 psf, indicative of moderate to very stiff soils. The lowest unconfined compressive strength value (1008 psf) was recorded in Boring B-1 in the upper one foot. As shown in Figure 4, this soil stratum is classified as clayey sand. Unconfined compressive strength testing indicates the cohesive properties of soils; it does not account for the shear strength characteristics of coarse-grained soils. Therefore, unconfined compressive strength values are typically lower for soils intermixed with fine-grained (clay, silt) and course-grained (sand, gravel) particles. c. Atterberg Limit Atterberg limits describe the consistency of soils (typically fine-grained soils) with varying moisture contents. Depending on the moisture content of a particular soil, the behavior of the soil can be divided into four basic states solid, semisolid, plastic and liquid. Atterberg limits can also be important for the classification of a soil sample. Atterberg limits generally comprise of two tests called the plastic limit and liquid limit; however, a third test named the shrinkage limit can also be performed. The moisture content at the point of transition from a semisolid to plastic state is defined as the plastic limit. The moisture content at the point of transition from a plastic state to liquid state is defined as the liquid limit.

11 Proposed Glass Residence Page 8 There are several indices that are derived from the Atterberg limits and/or moisture contents. Two of the more important indices are the plasticity index (PI) and liquidity index (LI). The plasticity index is the difference between the liquid and plastic limits. The plasticity index (PI) is the range over which a soil acts in a plastic state. Geotechnical studies have shown that the more plastic a soil (i.e., possessing a higher plasticity), the more compressive and expansive it will act. The PI values recorded at this site ranged from 9 to 19 percent indicative of low to moderate plastic soils. However, the moisture content of the soils relative to their plastic limits also play an important role in determining the volume change potential at various moisture states. The liquidity index scales the moisture content of a given soil relative to the Atterberg limits. If the liquidity index is negative, the soil will behave as a brittle material (solid to semisolid state) and is generally indicative of drier soil moisture conditions. If the liquidity index is between 0 and 1, the soil will behave as a plastic material and is generally indicative of wetter soil moisture conditions. If the liquidity index is greater than 1, the soil will behave as a liquid. Generally, as the liquidity index increases, the soil moisture conditions become increasingly wetter. Figure 9 plots the liquidity index (LI) for each geotechnical boring. Based on Figure 9, higher LI values were encountered in the upper three feet indicative of wetter soil moisture conditions in the upper strata. However, drier soil conditions were encountered between 3 to 7 feet based on lower LI values of -0.2 or lower. Boring B-2 encountered comparatively the highest LI values at deeper depths approaching 1.0, which corresponds to the documented water seepage at deeper depths. d. Total Soil Suction Total soil suction refers to the measurement of the free energy state of the porewater exerted on the pore-water by the soil matrix. Where moisture content values describe how much moisture is in the soil, total soil suction describes where the moisture is going. In unsaturated soil conditions, soil moisture moves from a location of low suction to areas of high suction, otherwise stated, from a higher energy location to a lower energy location. Soil suction becomes the dominant force for soil moisture flow in unsaturated soil conditions and the gravity force component becomes comparably small.

12 Proposed Glass Residence Page 9 The total soil suction values recorded at this site ranged from 3.36 to 3.68 pf, which are qualitatively described as low to near equilibrium total soil suction values. Figure 8 plots the total soil suction values for each geotechnical boring. Soil moisture tends to migrate from wets soils to dry soils, or from low total soil suction to areas of high to soil suction. Based on Figure 8, the total soil suction values are near equal within the upper 15 feet. e. Free Swell Tests Absorption free swell tests were also performed on 6 selected samples to evaluate the swell potential of these soils at their in-situ moisture and suction states. The swell tests performed on the soil samples at their respective overburden pressures indicate ranges of swells of -0.29% to 0.30%. The complete results of these tests are presented in Figure 10. The average swell value was approximately percent, which indicates the lack of soil heave with the addition of free water. G. ELECTRICAL RESISTIVITY PROFILES Methods used to analyze and collect the field data, as well as interpretation of these geo-electrical moisture/material imaging resistivity (GMMIR) profiles is based upon a patented process, US Patent S/N 6,295,512. All rights reserved. Resistivity profiling is used throughout the mining, engineering and environmental fields to evaluate the moisture and material properties of rock materials. I. Geoelectrical Imaging Assumptions Two-dimensional subsurface objects are assumed in the inversion process which implies that the resistivity structure modeled is parallel to the profile and has some two-dimensional effects perpendicular to the profile. The resistivity technique allows for some limited "sight" or three-dimensional effects away from the exact profile line. The resolution of electrical resistivity methods decreases exponentially with depth. However, in the shallow subsurface, i.e., in the upper 100 feet of the earth, the resolution power of the resistivity method is good. Use of resistivity imaging

13 Proposed Glass Residence Page 10 coupled with control information from borings including true resistivity measurements of the soil samples and the identification of stratigraphic boundaries and subsurface water seepage from site-specific soil borings greatly enhance the electrical resistivity tool. Electrical resistivity methods do not provide information regarding the density of the soil materials. Instead, they provide indications of the relative ease or difficulty with which electrical current passes through the soil and rock materials providing information regarding the moisture and material differences and resistivity contrasts at a site with depth. The purpose of the electrical resistivity profiling is to evaluate the variation of the subsurface and surficial expansive clay soils encountered at this site. II. Geoelectrical Computer Data Modeling Two-dimensional computer inversions were performed using a least-squares approximation to provide the "best fit" between the apparent resistivity field data and the assumed computer resistivity structure model. The electrical resistivity scale shown on the profile was truncated at 500 ohm-m to provide a uniform scale of resistivity values for comparison purposes. Actual resistivity values of the soils and/or materials in the red areas may be slightly greater than 500 ohm-m. III. Geophysical Exploration As shown on Figure 11, the color scales of Profile R1 range from ice blue to brown. The ice blue color represents the lowest resistivity values on the order of 1.5 ohm-m or less while the brown color represents the highest measured resistivity value on the order of 500 ohm-m. For discussion purposes of this report, BCI has outlined its terminology regarding the classification of the color scale shown on the resistivity profile:

14 Proposed Glass Residence Page 11 0 to 3.0 ohm-m: extremely low 3.0 to 7.5 ohm-m: low 7.5 to 15 ohm-m: moderately low 15 to 30 ohm-m: moderate 30 to 50 ohm-m: moderately high 50 to 500 ohm-m: high to very high The following paragraphs summarize the relationship between these resistivity values (and the subsequent colors) and their respective soil types and moisture states. Resistivity values on the order of 3.0 ohm-m or less as shown by ice blue colors are usually indicative of wet to very wet soils with some possible associated water seepage. Based on the GMMIR profile, no extremely low resistivity values were encountered at this site. Relatively low resistivity soils (3.0 to 7.5 ohm-m) were recorded in each of the GMMIR profiles. Typically, these resistivity values are indicative of high PI clays and/or a soil regime having high moisture contents in relation to their corresponding plastic limits. Based on the soil conditions encountered, we are of the opinion that these low resistivity values are indicative of soils with their moisture contents above their respective plastic limit values. Moderately low resistivity values (7.5 to 15 ohm-m) are represented by green colors. Typically, these values represent a drier clayey soil regime having moisture contents at or lower than their corresponding plastic limits and/or lower PI clay materials with concentrations of sand, silt and/or gravel. Based on existing soil conditions encountered in Borings B-1 and B-2, moderately low resistivity values represent lower PI clay soils with sand and silt identified as sandy lean clay in the boring logs. Moderate resistivity values on the order of 15 to 24 ohm-m are represented by the yellow and orange colors. Considering the soil conditions at this site, resistivity values of this magnitude are indicative of more granular-type soils such as clayey sands.

15 Proposed Glass Residence Page 12 Based on Profile R1, low resistivity values were encountered between moderately low to moderate resistivity values. These conditions were reflected in the geotechnical borings. No anomalous subsurface condition(s) are readily apparent in Profile R1. The moisture and material properties of the soil samples retrieved from the geotechnical borings does not appear to significantly deviate from the house pad based on Profile R1. H. ANALYSIS AND RECOMMENDATIONS I. Foundation System Options The active clays encountered at this site are subject to moisture related volume changes. The soils at this site were relatively dry to moist within the active zone based upon the March 17, 2004 geotechnical study. The dry state of the underlying clays could cause some upward movement with the absorption of free water. Various types of foundation systems currently are used for support of residential structures. The three most common types of foundation systems used in the Houston area are the following: Type 1. Pier-and-beam foundations with deep drilled shafts founded below the zone of seasonal moisture variation and the with the floor system suspended above grade. Type 2. Slab-on-grade foundation systems supported on drilled shaft extending below the zone of seasonal moisture variation. Type 3. Slab-on-grade foundation systems that are supported in the shallow surface soils. Further, two perspectives of foundation design are inherent in these foundation systems. The first perspective, Mode A, is the design of the slab-on-grade foundations from a soil-structure interaction standpoint to withstand excessive deflections, shear and bending moments. The second perspective, Mode B, is the design of the interior floor systems and deep pier foundation systems in the

16 Proposed Glass Residence Page 13 case for Type 1 or Type 2 to withstand these shears, moments and deflections. In each of these designs, compatibility between the interior and exterior cosmetic finishes and the foundation rigidity or flexibility must be considered. Obviously, some level of risk is associated with all types of foundation systems and a zero-risk foundation system does not exist. Further, post-construction homeowner maintenance of the foundations including, but not limited to maintenance of positive drainage around the house on all sides and the planting of vegetation no closer than its mature height to the foundation are essential for performance of all types of foundations and especially Type 2 and Type 3 foundations in Mode A design and in Type 1 foundations in Mode B design. This achievement of site equilibrium is the cornerstone of the PTI design, which assumes that the slab-on-grade foundation is affected only by climatic changes in the moisture addition and moisture subtraction in the soil and that the soils have achieved an equilibrium state with their surrounding climatic conditions. Each of above referenced systems is considered viable for various site conditions. In sites with potential near surface ground water or surface water seepage and/or sites with dry or highly expansive clays and deep fills, the surficial soils must be treated by replacement with more inert soils, injection with chemicals or water, and/or possible other drainage considerations before a Type 3 foundation system would be recommended. If these site conditions are not corrected prior to construction, then the Type 1 design is considered to be the most positive foundation option. Further, even with treatment of the soils, the Type 2 and Type 3 foundations must still be designed to withstand climatic fluctuations in moisture around the foundation and some movements are to be expected in these systems. In these situations, a Type 1 foundation will be the most positive foundation type from a geo-structural soil-structure interaction perspective (Mode A ), and the other systems will inherently have more risk of differential movements due to soilstructure interactions. In situations were inert or low expansive soils or fills are present and concerns regarding downward movements or settlements exist, then the use of a Type 2 foundation may be most appropriate.

17 Proposed Glass Residence Page 14 In BCI's opinion, the selection of the most appropriate foundation system for a given site is a function of many factors including, but not limited to: 1) the soil and rock conditions, 2) the climate, 3) the presence of vegetation, 4) the drainage and site topography, 5) the economics of the market, 6) customer requirements, 7) city or government requirements, 8) warranty company and mortgage company requirements and 9) the level of risk acceptable to the owners and developers for the project. II. Type 1 Foundation System BCI understands that a Type 1 design is currently being considered for this site. In addition, BCI understands that the finish foundation floor will be approximately 4 to 5 feet above current grade elevation to improve drainage conditions and lower the risk of flooding. All depths documented hereinto in this report are in reference to the ground elevation at the time of our investigation in March From a purely geotechnical soil-structure interaction perspective or Mode A design, Type 1 is the least risky foundation system. However, the Type 1 foundation system is subject to post-construction movement if the drilled piers are not stable and the wood elements are subject to moisture effects, which can lead to structural floor support issues unless proper drainage is provided in and around the crawl space of this system (Mode B ). The active soils encountered at this site are subject to some moisture related volume changes. Any shallow or near-surface type of foundation system could be subject to some differential movements. Foundations for the proposed structures that are founded below the zone of seasonal moisture variations would be the most positive means of supporting the proposed structures. The pier-and-beam foundation system provides a structurally suspended floor slab supported above grade on drilled shafts extending below the zone of seasonal moisture variation. Based upon review of the total soil suction laboratory test results and the soil suction profile (Figure 8), we are of the opinion that a constant total soil suction value of 3.5 pf at a depth of 12 feet is reasonable for this site. The depth to constant suction will terminate within a lean clay with sand stratum as described in Figures 4 and 5.

18 Proposed Glass Residence Page 15 a. Static Pier Analysis For a Type 1 foundation system, the following information is provided for general consideration and is accurate for the total boring depth of 35 feet which was scheduled for this site. The design parameters for proprietary piering systems and for depths below 35 feet should be further estimated and evaluated by the design structural engineer. In general, the total allowable resistance for a cast-in-place piling system is comprised of both end bearing and side resistance components. Depending upon the layering and soils present at depth, it is difficult to estimate at what pile deformation the individual components of end or side resistance will be mobilized. However, the rule is that some components of both the end bearing and the side resistance will be mobilized immediately upon loading and deformation. However, Vesic (1977) reports that it takes substantially less strain or deformation (on the order of 0.25 to 0.5 inches) to mobilize the side resistance component for piles regardless of pile size and length in contrast to the end bearing component mobilization of ultimate point resistance of a pile which requires a displacement on the order of approximately 10 percent of the pile tip diameter for driven piles and as much as 30 percent of the pile tip diameter for bored piles. Coyle and Reese (1966) indicate that in determining the load capacity of a pile, consideration should be given to the relative deformations between the soil and the pile as well as the compressibility of the soil pile system. The ultimate skin friction increments along the pile are not necessarily directly additive, nor is the ultimate end bearing additive to the ultimate skin friction or side resistance. Therefore, as a general rule, it is difficult to predict the soil-structure interaction for drilled piers or piles and a conservative approach should be taken by the design engineer with end bearing considered as a factor of safety. Based on the presence of water seepage at depths of approximately 17 to 22 feet below grade, cast-in-place piers should bear above the documented water table. Based upon the allowable bearing pressure equation for deep foundations, an allowable end bearing resistance of 3,500 pounds per square foot (psf) is calculated for piers bearing in the sandy lean clay stratum between 13 to 21 feet below grade using a factor of safety of 3.

19 Proposed Glass Residence Page 16 Assuming the piers are bearing approximately 15 feet below grade with an end bearing pressure of 3,500 psf, based on the consolidation test, the primary consolidation settlement for these piers would be less than 1-inch. However, if the water table rises near the surface due to climatic conditions, the estimated primary consolidation settlement would be on the order of 1-1/4 inches. Based on soil types and loading conditions, BCI is of the opinion that some of the estimated consolidation settlement will occur during construction, or shortly thereafter. Based upon the allowable bearing pressure equation for deep foundations, an allowable side resistance of 450 psf is recommended for compressive loading and 325 psf is recommended to resist tensile uplift forces (using a factor of safety of 2) for piers bearing in the yellowish gray sandy lean clay stratum. These side resistance values should be used below the moisture and movement active zone, which in this case is estimated at 12 feet below existing grade. Depth of embedment will be reduced when considering the amount of dead load on the pier. Some caution should be used in application of dead load to reduce pier length and we recommend that the structural design engineer provide accurate estimates and bases for the dead load values used. Uplift resistance may also be derived from using an underreamed bell, which should be between 2.5 and 3 times the shaft diameter founded below the zone of seasonal moisture variation. The pier should be continuously reinforced to resist the soil-induced uplift loads and any other structural loads influencing the structure as dictated by the structural design engineer. The actual uplift resistance of the bell due to cohesive and friction modes of shear failure should be analyzed by the project structural engineer. Additional construction and design recommendations should be provided by the proprietary piering system manufacturer and the design structural engineer. b. Estimated Soil Induced Uplift Pressures The active clay soils encountered at this site will induce some upward forces on piers/piles placed at this site. Based upon our soil property correlations, assuming that the upper 12 feet of the soils are within the moisture and movement

20 Proposed Glass Residence Page 17 active zone, we estimate that the uplift forces for piers/piles placed at this site will be approximately 800 psf acting uniformly around the shaft perimeter. c. Construction Considerations Concrete used for the shafts should have a slump of six (6) inches plus or minus one (1) inch and be placed in a manner to avoid striking the reinforcing steel and walls of the shaft during placement. Complete installation of individual shafts should be accomplished with an 8-hour period in order to help prevent deterioration of bearing surfaces. The drilling of individual shafts should be excavated in a continuous operation and concrete placed as soon as practical after completion of the drilling. No shaft should be left open for more than eight hours or overnight. Water seepage was encountered at approximately 17 to 22 feet below grade. The bore hole caved in at 17 and 21 feet below grade after drilling operations ceased. BCI recommends that the end bearing of the underreamed piers should be installed above these depths, if seepage does not allow construction, but not less than 15 feet. Due to the presence of water seepage, casing of the pier hole should be anticipated. If pier depths are less than 15 feet from existing grade, then BCI should be contacted to evaluate this effect on bearing and settlement. We recommend that the project structural design engineer be retained to observe and document the drilled shaft construction. The engineer, or his representative, should document the shaft diameter, depth, cleanliness, and plumbness of the shaft and the type of bearing material immediately prior to placement of the concrete. Significant deviations from the specified or anticipated conditions should be reported to the owner s representative and to the foundation designer. The drilled shaft excavations should be observed after the bottom of the hole is leveled, cleared of any mud or extraneous material, and dewatered, if necessary and immediately before placement of concrete. The pier excavations should be free of loose soil, ponded water or debris. If the structural engineer deems necessary, a void box may be installed underneath the grade beams. Based on the PVM values calculated at this site, the void box should have a minimum depth of 4 inches.

21 Proposed Glass Residence Page 18 III. Type 2 Foundation System In situations were inert or low expansive soils or fills are present and concerns regarding downward movements or settlements exist, then the use of a Type 2 foundation may be most appropriate. Based on the soil conditions encountered at this site, BCI is of the opinion that a Type 2 foundation system would be a viable alternative to a Type 1 system. Type 2 foundation systems will allow upward movement but will help mitigate downward movement if the piers are designed and founded properly. Applicable design parameters for a Type 2 foundation system may be found in the sections labeled Type 1 Foundation System and Type 3 Foundation System. Inherent risks for slab-on-grade foundation systems are further discussed in the Foundation System Options section of the report. IV. Type 3 Foundation System The performance of these various systems is a function of the materials supporting them. Obviously, slab-on-grade foundations supported in the moisture active zone of the soil profile will potentially move differentially and behave differently than a completely suspend floor slab in Type 1 or by a pier supported slab as described by Type 2. Type 3 foundations are inherently subjected to more differential foundation movement; however, proper site preparation and appropriate structural design of slab-on-grade foundation systems allows their use in most circumstances. The owner should realize that a greater risk of movement is associated with a slab-on-grade foundation system, and some differential movements will occur through time. Control of these movements is a function of the maintenance of uniform moisture beneath and around the slab and proper placement of fill materials. The slab-on-grade design parameters provided in this report are based upon climatic effects only, and do not include the adverse affects of ponded water, previous or future trees, fill settlement, and utility line leaks or extreme moisture fluctuations due to capillary action of subterranean groundwater. Some differential movement of the slab should be anticipated during the life of the slab due to equilibration of moisture contents beneath the slab which prevents evapotranspiration of moisture from the ground.

22 Proposed Glass Residence Page 19 The effects of the trees or ponding water near the foundation may be modeled, if they are considered as higher risk possible conditions. Every effort should be made by the structural design engineer and homeowner to discuss these issues and develop appropriate remedial schemes to address them prior to construction. If these adverse effects are considered to be likely based upon the final house placement location, grading issues and tree/vegetation issues, then BCI can help model their effects, if any. Please notify us in writing if these adverse effects are to be considered in our analysis and recommendations. If the differential movements and total movements outlined in this report are not acceptable, or if concerns over external environmental effects from trees, utility line leaks, fill settlement or groundwater fluctuations are considered a large concern, then we recommend using a Type 1 or Type 2 foundation system. a. Estimated Potential Vertical Movements The soils present at this site consist predominantly of lean clays with low to moderate movement potential. In general, the clays were dry to moist at the time of the field investigation and will possibly experience volume changes with fluctuations in their moisture content. The lightly loaded interior floor slab placed on-grade will be subject to potential movement as a result of moisture induced volume changes in the surficial clays. Potential Vertical Movement (PVM) calculations for various soil profiles at the site were performed using the Texas Highway Department's Method (TxDOT) TEX 124-E, soil suction testing and our engineering judgment and are summarized in Table 1. The PVM values presented below do not include the effects of differential movements from uncontrolled water sources such as poor drainage, utility line leaks or migration of subsurface water from off site locations. These movements are total vertical movements and do not consider differential swell between any two points on the ground surface. The potential vertical movement (PVM) values provided above are based upon the soil stratigraphy found in the boring logs. If final grades are changed ± 18 inches, then BCI should be notified in writing so

23 Proposed Glass Residence Page 20 that we can review the effects of these grading changes upon the PVM values and other geotechnical issues. A reinforced (conventional rebar or post-tensioned) monolithic, slab-on-grade foundation system will need proper design and construction to resist and/or tolerate the moisture induced movements of the clays without inducing unacceptable distress in the foundation or superstructure. On the basis of laboratory tests and estimates of PVM, we recommend that the potential vertical movements (PVM) as outlined in Table 1 are used for slab design calculations at this site without any soil modification considering the cut and fill operations do not differ more than ± 18 inches from the available preliminary grading plans. These movements are total vertical movements and do not consider differential swell between any two points on the ground surface. If fills of more than 18 inches are contemplated with imported fills or with fills of higher plasticity indices than on-site soils samples in Borings B-1 and B-2, then BCI should be notified in writing so we can evaluate the impact of these fills, if any. b. Post-Tensioning Slab Design Parameters Design criteria for a slab designed in accordance with the Post-Tensioning Institute s (PTI) slab-on-grade design method have been developed. The PTI computer program (VOLFLO) was used to derive the PTI differential movements (y m ). We recommend that the structural engineer consider the limitations of the VOLFLO program by noting that the PTI VOLFLO algorithm provides minimum design parameters for slab-on-grade foundation system design. The structural engineer s judgment and experience should also be used to design the slab-ongrade system to account for variations in conditions affecting y m and e m values including review of the final grading plans to allow for construction over deep cut and fill sections where some settlements may occur. The edge moisture variation distances (e m ) for center lift and edge lift conditions were derived based on an Thornthwaite Index of +15 for the project site using the criteria provided in the PTI manual and other, more conservative methodologies.

24 Proposed Glass Residence Page 21 The edge moisture variation distances provided below in Table 1 are based upon the PTI manual minimum guidelines. The PTI design parameters provided below are applicable if adverse site conditions have been corrected and soil moisture conditions are controlled by the climate alone (i.e., not improper drainage, unforeseen subsurface seepage, placement of uncontrolled or deep fills, vegetation influence or water leaks). The performance of slab and movement magnitudes can be significantly influenced by landscaping maintenance, water line leaks, and trees present before and after construction. The Post-Tensioning Institute (PTI) method incorporates numerous design assumptions associated with the derivation of required variables needed to determine the soil design criteria. The PTI design also assumes that the site possesses positive drainage directed away from the structure and that the slab perimeter moisture regime will be uniformly maintained during the useful life-cycle of the post-tensioned slab. Table 1. Recommended PVM and PTI Slab Design Parameters Boring Center Lift Condition Edge Lift Condition PVM from TxDOT Dry Edge Moisture Variation Distance e m, ft Estimated Differential Movement y m, in Edge Moisture Variation Distance e m, ft Estimated Differential Movement y m, in B-1 and B-2 1-1/2* * on the order of Exterior grade and interior stiffener beams may be proportioned using an allowable soil bearing pressure of 2,000 pounds per square foot (psf) for beams placed in undisturbed natural soils. Exterior grade and interior stiffener beams may be proportioned using an allowable soil bearing pressure of 1,500 pounds per square foot (psf) for beams placed in properly compacted and monitored fill. We recommend that a field quality assurance soil testing laboratory/inspector observe the grade beam excavations prior to placing concrete. The foundation

25 Proposed Glass Residence Page 22 bearing area should be level or suitably benched. It should be free of loose soil, ponded water and debris prior to the inspection. The PTI design parameters provided in Table 1 are based upon climatic fluctuations in the moisture conditions around the slab. More severe conditions such as ponded water standing around the slab and/or the presence of vegetation planted near the perimeter of the foundation are not considered in the above design parameters. Movement magnitudes approaching the PVM values in Table 1 are possible if severe drainage conditions, ponded water, or plumbing leaks are occur. As a result, the above PTI design parameters are contingent upon positive drainage and vegetation planted at least the mature height of the vegetation away from the slab perimeter and properly compacted fills placed beneath and around the slab perimeter. I. EARTHWORK GUIDELINES I. Site Grading Any future cut and fill operations should be supervised by a qualified testing laboratory. A set of general guidelines for additional earthwork required at this site are provided in Appendix 1 Guidelines for the Placement of Controlled Earthwork of this report. Deep fill sections, other than minor fills produced during slab leveling of less than 6 inches, that will support the grade beams, should extend a minimum of 3 feet beyond the building line and then slope to natural grade on as flat a slope as practical or the fill section should be retained by a properly designed retaining wall. Generally, a maximum slope of 4 horizontal to 1 vertical is recommended. BCI should be contacted to provide additional recommendations if any slopes greater than 4 horizontal to 1 vertical or over 4 feet are planned within the project site so that slope stability analyses can be performed, if deemed necessary based upon the project specifics and upon written notification of the project structural engineer after final grading and design have been performed. If soft or compressible zones are identified during site grading and construction, or if obvious uncontrolled fill materials are noted between the boring locations within

26 Proposed Glass Residence Page 23 the building pad areas, then these areas should be over-excavated and replaced with properly compacted on-site fill or select fill. II. Surface Drainage Proper consideration to surface drainage is essential to the performance of a monolithic slab-on-grade. The overall grading must provide for positive drainage away from the structure. All grades must be adjusted to provide positive drainage away from the structure. As a minimum, all grades and swales shall be constructed to meet FHA minimum standards. It is recommended that slopes of about 2 to 3 percent be maintained a reasonable distance away from the perimeter of the structures to ensure that positive drainage is provided around the structures. The drainage swales and grades should be maintained for the life of the structure by the homeowner. Water permitted to pond next to the structures can result in soil movements that exceed those indicated in this report. Roof drains should divert water well away from the structure. Sidewalks and other concrete flatwork may also be subject to movement. Flat grades should be avoided particularly adjacent to the slab-on-grade foundation. Areas around sidewalks or drives should be graded to prevent trapping and holding water adjacent to these facilities or the residential foundation systems. III. Compaction Recommendations Compaction requirements for the various material types may be summarized in Table 2.

27 Proposed Glass Residence Page 24 Table 2. Compaction Recommendations for Various Materials Material Type Areas for Use Compaction to ASTM D698 at (x) of Optimum Moisture Recommended Thickness (in) Imported Fill Building Pad 95% at (0 to +5)%* as required for grade modification On-site Fill Outside Building Pad 95% at (-2 to +3)% as required for grade modification In-situ Soil Subgrade Beneath all fill and pavements 95% at (0 to +5)% 6 inches minimum *If fill depths exceeds three feet in depth underneath the building pad, BCI recommends a minimum compaction effort of 98% of the maximum dry density according to ASTM D-698.

28 Proposed Glass Residence Page 25 J. LIMITATIONS AND REPRODUCTIONS This geotechnical/geophysical Report is based on information supplied by the owner and/or others, and a visual survey of the elements exposed to Bryant Consultants, Inc. at the time of the field investigation. Bryant Consultants, Inc. will not be responsible for 1) knowledge of subsurface conditions substantially away from the borings and profiles 2) knowledge of cracks, or differential displacements that have occurred in a floor slab or flatwork without removing the floor covering and 3) any other element such as joists or beams and other structural members that are not readily visible by us. The boring and GMMIR profile locations were approximately determined by tape measurements from existing physical features. The locations and elevations of the borings should be considered accurate only to the degree implied by the methods used. Geophysical inverse methods are subject to errors and interpretation away from the profile line. Environmental errors may result in in-exact data which will provide some variation in the theoretical resistivity models after inversions of the same data sets. Non-uniqueness of the inverted data also may produce similar resistivity structure models using different raw data sets. Use of resistivity coupled with control information from borings including true resistivity measurements of the soil samples, identification of stratigraphic boundaries and the presence of groundwater greatly enhance the electrical resistivity tool. The conclusions and visual observations of this report are based in part upon the data obtained in the borings and upon the assumption that the soil conditions do not deviate from those observed. Any latent distress in areas not exposed cannot be anticipated without further destructive and/or intrusive testing. Unanticipated soil conditions are commonly encountered and cannot be fully determined by soil samples, test borings, or test pits. BCI further assumes that the conclusions drawn from this information are based in part on information gathered by others. Fluctuations in the level of the groundwater may occur due to variations in rainfall, temperatures, and other factors not present at the time the measurements were made. Samples obtained during the field operations will be retained 30 days after the issue date on the report. After this period, we will discard the samples unless otherwise notified by the owner in writing before the end of this period. The observations, discussions, recommendations and conclusions in this report are based solely on the geotechnical and geophysical explorations. If any additional information becomes available, then BCI reserves the right to evaluate the impact of this information on our opinions and conclusions and to revise our opinions and conclusions if necessary and warranted after review of the new information. The observed conditions are subject to change with the passage of time. This report does not constitute a guarantee or warranty as to future life, performance, need for repair or suitability for any other purpose at this site but as an evaluation only and that design and implementation of any repairs are responsibilities of others. Silence in this report regarding any environmental issues should not be a tacit assumption that the potential for environmental issues does not exist. Any environmental evaluation or investigation was beyond the scope of this report and should be performed by others, if warranted. This investigation was performed by Bryant Consultants, Inc. and the engineer in a manner consistent with that level of care and skill ordinarily exercised by members of the profession currently practicing in the same locality under similar conditions. Unless otherwise indicated, this geotechnical report was prepared exclusively for Mr. Steve Glass. and expressly for purposes indicated by for Mr. Steve Glass. Permission for use by any other persons for any purpose, or by Mr. Steve Glass for a different purpose must be provided by Bryant Consultants, Inc. in writing. Any use made of this investigation and/or the conclusions and recommendations contained herein and any reliance thereon shall be specifically subject to the following limitation of liability: In recognition of the relative risk and benefits of the project to user and BCI, the risks have been allocated such that user agrees, to the fullest extent permitted by law, to limit the liability of BCI to user for any and all claims, losses, costs, damages of any nature whatsoever or claims expenses from any cause or causes, including attorney s fees and costs and expert witness fees and costs, so that the total aggregate liability of the BCI to user shall not exceed five thousand dollars ($2,500.00) unless otherwise specifically agreed in writing. It is intended that this limitation apply to any and all liability or causes of action however alleged or arising, unless otherwise prohibited by law. For the purpose of this provision, BCI shall include the officers, directors, shareholders, partners, agents, servants and employees of BCI. This limitation is applicable to BCI s negligence or other fault in whole or in part. The reproduction of this report, or any part thereof, supplied to persons other than the owner, should indicate that this study was made for foundation design purposes only and that verification of the subsurface conditions for purposes of determining difficulty of excavation, traffic ability, etc., are responsibilities of others. Slope stability analyses are beyond

29 Proposed Glass Residence Page 26 the scope of this project. These services may be performed at an additional cost upon your written request. Should you have any questions pertaining to any aspect of this report, or if we can be of further assistance to you, please do not hesitate to call on us.

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32 Ak Feet Legend Harris County Soil Survey Ak - Addicks-Urban land complex Figure 3 - GIS Map of Site

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34

35 Figure 6. Moisture Content Profiles B-1 B-2 Moisture Content, % Depth, ft

36 Figure 7. Hand Penetrometer Profiles B-1 B-2 Hand Penetrometer, tsf Depth, ft

37 Figure 8. Total Soil Suction Profiles B-1 B Total Soil Suction, pf Depth, ft

38 Figure 9. Liquidity Index Profiles B-1 B-2 Liquidity Index WETTER DRIER Depth, ft

39 FIGURE 10. SWELL TEST RESULTS BCI Project Number PRE-SWELL FINAL PERCENT BORING DEPTH ATTERBERG LIMITS MOISTURE MOISTURE LOAD VERTICAL NUMBER (ft) LL PL PI CONTENT CONTENT (psf) SWELL B B B B B B Average Min Max 0.30 Std. Dev PROCEDURE 1. SAMPLE PLACED IN CONFINING RING, DESIGN LOAD (INCLUDING OVERBURDEN) APPLIED, FREE WATER WITH SURFACTANT MADE AVAILABLE, AND SAMPLE ALLOWED TO SWELL COMPLETELY. 2. LOAD REMOVED AND FINAL MOISTURE CONTENT DETERMINED.

40 Figure 11. GMMIR Profiles, Proposed Glass Residence BCI Project Survey Date: 3/17/04 Depth (m) B Profile R1. East to West direction across the Lot Electrical Resistivity (ohm-m) Notes: 1. Data at lower corners is interpolated. 2. Structure, Boring and Vegetation positions are approximate. 3. Patent Process, All Rights Reserved. US Patent S/N 6,295,512.

41 View of residential lot viewing towards the N direction. View of the approximate location of the residential house pad. Figure 12: Photographic Survey of Proposed Glass Residence