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Home My WebLink AboutAMREP New Facility - SW 3180201_ 11761-A Summit Corporate Center - GEO Report REPORT OF SUBSURFACE EXPLORATION SUMMIT CORPORATE CENTER SALISBURY, NORTH CAROLINA ECS PROJECT NO. 08-11761-A JULY 12, 2016 REPORT OF SUBSURFACE EXPLORATION Summit Corporate Center Salisbury, North Carolina Prepared For: Mr. Scott Shelton Project Manager RowanWORKS 204 East Innes Street, Suite 220 Salisbury, North Carolina Prepared By: ECS CAROLINAS, LLP 1812 Center Park Drive Suite D Charlotte, NC 28217 ECS Project No: 08-11761-A Report Date: July 12, 2016 Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 2 July 12, 2016 1. INTRODUCTION 1.1. Project Information The project site is approximately 5 acres in size and is located off of Julian Road in Salisbury, North Carolina. We understand the project will consist of the construction of a 30,000 square- foot (SF) facility with 2,000 SF of office space. Surface parking and drive areas will be constructed around the remainder of the site. Based on our review of Google Earth and our subsequent site visit, the site is undeveloped and moderately to heavily wooded. Based on the topographic map provided, the existing topography at the site generally slopes from a high elevation of approximately 796 feet along the southern portion of the site to a low elevation of approximately 786 feet along the northern portion of the site for a total relief of 10 feet. Final design elevations were not provided to us at the time of this exploration. Therefore, we assume mass grading will consist of cut and fill depth on the order of 5 feet or less. Construction methodology and structural loading conditions have not been provided to us at this time. However, we anticipate the proposed structure will be either wood-framed with brick veneer or concrete masonry unit (CMU) construction with maximum column and wall footing loads on the order of 100 kips and 4 kips per linear foot, respectively. No other information was available at the time of this report. 1.2. Scope of Services Our scope of services included a subsurface exploration with soil test borings, engineering analysis of the foundation support options, and preparation of this report with our recommendations. The subsurface exploration included a total of ten (10) soil test borings (B-1 through B-10) drilled to depths ranging from approximately 19 to 20 feet below existing grades. Approximate boring locations are shown on the Boring Location Diagram (Figure 2) included in the Appendix. The soil borings were performed using a SIMCO 2400 track-mounted drill rig using continuous-flight, hollow-stem augers. 2. FIELD SERVICES 2.1. Test Locations The soil boring locations were selected and located in the field by ECS using a handheld GPS device and existing landmarks as reference. The approximate test locations are shown on the Boring Location Diagram (Figure 2) presented in the Appendix of this report and should be considered accurate only to the degree implied by the method used to obtain them. Ground surface elevations at the boring locations were estimated from the provided topographic survey and should be considered approximate. 2.2. Soil Test Borings Ten (10) soil test borings were drilled to evaluate the stratification and engineering properties of the subsurface soils at the project site. Standard Penetration Tests (SPT’s) were performed at designated intervals in general accordance with ASTM D 1586. The Standard Penetration Test is used to provide an index for estimating soil strength and density. In conjunction with the penetration testing, split-barrel soil samples were recovered for soil classification at each test interval. Boring Logs are included in the Appendix. Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 3 July 12, 2016 The drill crew also maintained a field log of the soils encountered at each of the boring locations. After recovery, each sample was removed from the split-spoon sampler and visually classified. Representative portions of each sample were then sealed and brought to our laboratory in Charlotte, North Carolina for further visual examination and laboratory testing. Groundwater measurements were attempted at the termination of drilling at each boring location. 3. LABORATORY SERVICES Soil samples were collected from the borings and examined in our laboratory to check field classifications and to determine pertinent engineering properties. Data obtained from the borings and our visual/manual examinations are included on the respective boring logs in the Appendix. 3.1. Soil Classification A geotechnical staff professional classified each soil sample on the basis of color, texture, and plasticity characteristics in general accordance with the Unified Soil Classification System (USCS). The soil engineer then grouped the various soil types into the major zones noted on the boring logs. The stratification lines designating the interfaces between earth materials on the boring logs and profiles are approximate; in situ, the transition between strata may be gradual in both the vertical and horizontal directions. The results of the visual classifications are presented on the Boring Logs included in the Appendix. 4. SITE AND SUBSURFACE FINDINGS 4.1. Area Geology The site is located in the Piedmont Physiographic Province of North Carolina. The native soils in the Piedmont Province consist mainly of residuum with underlying saprolites weathered from the parent bedrock, which can be found in both weathered and unweathered states. Although the surficial materials normally retain the structure of the original parent bedrock, they typically have a much lower density and exhibit strengths and other engineering properties typical of soil. In a mature weathering profile of the Piedmont Province, the soils are generally found to be finer grained at the surface where more extensive weathering has occurred. The particle size of the soils generally becomes more granular with increasing depth and gradually changes first to weathered and finally to unweathered parent bedrock. The mineral composition of the parent rock and the environment in which weathering occurs largely control the resulting soil's engineering characteristics. The residual soils are the product of the weathering of the parent bedrock. 4.2. Subsurface Conditions The subsurface conditions at the site, as indicated by the borings, generally consisted of residual soils, partially weathered rock (PWR), and refusal materials to the depths explored. The generalized subsurface conditions are described below. For soil stratification at a particular test location, the respective Boring Log found in the Appendix should be reviewed. A layer of surficial organic laden soil, approximately 2 to 3½ inches thick, was encountered at the existing ground surface at Borings B-1 through B-10. The organic laden soil depths provided in this report and on the individual Boring Logs are based on driller observation and should be considered approximate. Since a bulldozer was used to gain access to the boring locations, some of the surficial organic laden soil may have been removed during clearing. Please note that these reported values should not be used in determining removal quantities. Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 4 July 12, 2016 Residual soils were encountered beneath the surficial materials at Borings B-1 through B-10. Residual soils are formed by the in-place chemical and mechanical weathering of the parent bedrock. The residual soils encountered in the borings generally consisted of Fat CLAY (CH), Sandy CLAY (CL), Clayey SAND (SC), Sandy SILT (ML), and Silty SAND (SM) exhibiting SPT N-values ranging from 4 to 94 blows per foot (bpf), with a majority of the N-values between 10 and 32 bpf. Borings B-1 and B-4 through B-10 were terminated in the residual soils at depths of approximately 20 feet below existing grade. Partially weathered rock (PWR) was encountered beneath the residual soils at Borings B-2 and B-3. The top of PWR was encountered at depths ranging from approximately 8 feet to 17 feet below existing grades. A lens of PWR was encountered at Boring B-2 from approximately 8 to 12 feet and at B-10 from approximately 5½ to 8 feet below existing grades. PWR is defined as residual material exhibiting SPT N-values greater than 100 bpf. The PWR encountered generally consisted of Sandy Silt (ML) and Silty Sand (SM) exhibiting SPT N-values of 50 blows per 5 inches of penetration to 50 blows per 3 inches of penetration. Boring B-3 was terminated in PWR at a depth of approximately 20 feet below existing grades. Auger refusal was encountered at Boring B-2 at a depth of approximately 19 feet below existing grades. Auger refusal indicates the presence of material that permitted no further advancement of the hollow stem auger or split spoon sampler. Rock coring would be required to evaluate the character and continuity of the refusal materials; however, rock coring was beyond the scope of this investigation. 4.3. Groundwater Observations Groundwater measurements were attempted at the termination of drilling at the time of our exploration. Groundwater was encountered at Boring B-1 at a depth of approximately 17 feet below existing ground surface. The remaining borings were dry at the time groundwater was measured. Borehole cave-in depths were observed at each boring location at depths ranging from approximately 15.1 feet to 17.7 feet below the existing ground surface. Cave-in of a soil test boring can be caused by groundwater hydrostatic pressure, weak soil layers, and/or drilling activities (i.e. drilling fluid circulation or advancement of bit). Fluctuations in the groundwater elevation should be expected depending on precipitation, run- off, utility leaks, and other factors not evident at the time of our evaluation. Normally, highest groundwater levels occur in late winter and spring and the lowest levels occur in late summer and fall. Depending on time of construction, groundwater may be encountered at shallower depths and locations not explored during this study. If encountered during construction, engineering personnel from our office should be notified immediately. 5. CONCLUSIONS AND RECOMMENDATIONS The borings performed at this site represent the subsurface conditions at the location of the borings. Due to inconsistencies associated with the prevailing geology, there can be changes in the subsurface conditions over relatively short distances that have not been disclosed by the results of the test location performed. Consequently, there may be undisclosed subsurface conditions that require special treatment or additional preparation once these conditions are revealed during construction. Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 5 July 12, 2016 Our evaluation of foundation support conditions has been based on our understanding of the site, project information, and the data obtained in our exploration. The general subsurface conditions utilized in our foundation evaluation have been based on interpolation of subsurface data between and away from the borings. In evaluating the boring data, we have examined previous correlations between penetration resistance values and foundation bearing pressures observed in soil conditions similar to those at your site. 5.1. Organic Laden Soils A layer of surficial organic laden soil, ranging from approximately 2 to 3½ inches, was encountered at the ground surface. Since a bulldozer was used to gain access to a majority of the boring locations, some of the surficial organic laden soils may have been removed during clearing. Please note that these reported values should not be used in determining topsoil removal quantities. The surficial organic laden soil is typically a dark-colored soil material containing roots, fibrous matter, and/or other organic components, and is generally unsuitable for support of engineering fill, foundations, or slabs-on-grade. ECS has not performed laboratory testing to determine the organic content or other horticultural properties of the observed surficial organic laden soils. Therefore, the phrase “surficial organic laden soil” is not intended to indicate suitability for landscaping and/or other purposes. The surficial organic laden soil depths provided in this report and on the individual Boring Logs are based on driller observations and should be considered approximate. Please note that the transition from surficial organic laden soils to underlying materials may be gradual, and therefore the observation and measurement of the surficial organic laden soil depth is approximate. Actual surficial organic laden soil depths should be expected to vary and generally increases with the amount of vegetation present over the site. 5.2. Moisture Sensitive Soils (CH) Fat CLAY (CH) was encountered at Boring B-3 at depths ranging from approximately 3 to 5½ feet below existing grades. Soils classified as CH are fine-grained and have a Liquid Limit greater than 50 percent. Additionally, CH soils are considered highly moisture sensitive and can shrink and swell with moisture variations. Depending on final design grades, some of the CH soils may be removed during mass grading or excavated during foundation installation. CH soils should not be used for direct support of foundations, slabs-on-grade, or pavement subgrades. CH encountered within proposed structural areas should be undercut and replaced with low plasticity engineered fill to a minimum depth of 2 feet below foundations and 2 feet below subgrade elevations in slab and pavement areas. The quality of the subgrade soils should be evaluated by the geotechnical engineer on a case-by-case basis in order to evaluate the need for remediation. As previously mentioned, some isolated undercutting in the vicinity of Boring B-3 (building pad) should be anticipated. 5.3. Weak Near-Surface Soils Weak near-surface soils, with an N-value of 5 bpf or less, were encountered at Boring B-7 and extended to depths of approximately 3 feet below existing grades. In their present condition, these soils are generally considered marginally suitable to unsuitable for fill placement, foundations, floor slabs and pavement subgrades and should be undercut from beneath structural areas. Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 6 July 12, 2016 Pending a successful proofroll and acceptable dynamic cone penetrometer (DCP) testing, these soils may remain in place. However, if these soils do not pass a proofroll or DCP testing, some undercutting and/or recompaction should be anticipated. The resulting undercut should be backfilled with structural fill placed and compacted in accordance with the recommendations contained in this report. This should be further evaluated by ECS personnel in the field during construction. Depending on final design grades, some of these soils may be removed or filled over during site grading operations. 5.4. Seismic Site Classification The North Carolina Building Code (NCBC) requires that the stiffness of the top 100-ft of soil profile be evaluated in determining a site seismic classification. The method for determining the Site Class is presented in Section 1613 of the NCBC. The seismic Site Class is typically determined by calculating a weighted average of the N-values or shear wave velocities recorded to a depth of 100 feet within the proposed building footprint. The SPT values measured in the soil profile at the site indicate that a seismic site class of “D” is appropriate for this project. 5.5. Structure Foundations Provided the recommendations outlined herein are implemented, the proposed building can be adequately supported on a shallow foundation system consisting of spread footings bearing on low plasticity residual soil or newly-placed engineered fill. A bearing capacity of up to 3,000 psf is recommended for foundations bearing on approved low plasticity residual soil or newly-placed engineered fill. As previously mentioned, CH soils should not be used for direct support of foundations or slabs- on-grade. CH soils encountered should be undercut and replaced with approved engineered fill to a minimum depth of 2 feet below foundations provided that the resulting subgrade is stable. For this project, minimum wall and column footing dimensions of 18 and 24 inches, respectively, should be maintained to reduce the possibility of a localized, “punching” type, shear failure. Exterior foundations and foundations in unheated areas should be embedded deep enough below exterior grades to reduce potential movements from frost action or excessive drying shrinkage. For this region, we recommend footings bear at least 18 inches below finished grade. Total settlement is anticipated to be less than 1 inch, while differential settlement between columns is anticipated to be less than ½ inch for shallow foundations bearing on low plasticity residual soil or newly-placed structural fill. Foundation geometry, loading conditions, and/or bearing strata different than those described in this report may result in magnitudes of settlement inconsistent with the previous estimates. 5.6. Slab-On-Grade Support Slabs-on-grade can be adequately supported on undisturbed low plasticity natural soils or newly-placed engineered fill provided the site preparation and fill recommendations outlined herein are implemented. For a properly prepared site, a modulus of subgrade reaction (ks) for the soil of 90 pounds per cubic inch for the soil can be used. This value is representative of a 1- ft square loaded area and may need to be adjusted depending on the size and shape of the loaded area and depending on the method of structural analysis. Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 7 July 12, 2016 CH soils should not be used for direct support of slabs-on-grade. If these soils are encountered at or near final design grades, they should be undercut and replaced with approved engineered fill to a minimum depth of 2 feet below the slab-on-grade provided that the resulting subgrade is stable. We recommend the slab-on-grade be underlain by a minimum of 4 inches of granular material having a maximum aggregate size of 1½ inches and no more than 2 percent fines. Prior to placing the granular material, the floor subgrade soil should be properly compacted, proofrolled, and free of standing water, mud, and frozen soil. A properly designed and constructed capillary break layer can often eliminate the need for a moisture retarder and can assist in more uniform curing of concrete. If a vapor retarder is considered to provide additional moisture protection, special attention should be given to the surface curing of the slabs to minimize uneven drying of the slabs and associated cracking and/or slab curling. The use of a blotter or cushion layer above the vapor retarder can also be considered for project specific reasons. Please refer to ACI 302.1R04 Guide for Concrete Floor and Slab Construction and ASTM E 1643 Standard Practice for Installation of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs for additional guidance on this issue. ECS recommends that the slab be isolated from the footings so differential settlement of the structure will not induce shear stresses on the floor slab. Also, in order to minimize the crack width of shrinkage cracks that may develop near the surface of the slab, we recommend mesh reinforcement as a minimum be included in the design of the floor slab. For maximum effectiveness, temperature and shrinkage reinforcements in slabs on ground should be positioned in the upper third of the slab thickness. The Wire Reinforcement Institute recommends the mesh reinforcement be placed 2 inches below the slab surface or upper one- third of slab thickness, whichever is closer to the surface. Adequate construction joints, contraction joints and isolation joints should also be provided in the slab to reduce the impacts of cracking and shrinkage. Please refer to ACI 302.1R04 Guide for Concrete Floor and Slab Construction for additional information regarding concrete slab joint design. 5.7. Pavement Considerations Undisturbed low-plasticity residual soils or newly placed engineered fill can provide adequate support for pavement structures and walkways designed for appropriate subgrade strength and traffic characteristics. Based on the soil types encountered in the soil test borings, we recommend a CBR value of 3 be used in design of the project pavements. For the design and construction of exterior pavements, the subgrades should be prepared in accordance with the recommendations in the “Site and Subgrade Preparation” and “Engineered Fill” sections of this report. We emphasize that good base course drainage is essential for successful pavement performance. Water buildup in the base course will result in premature pavement failures. The subgrade and pavement should be graded to provide effective runoff to either the outer limits of the paved area or to catch basins so that standing water will not accumulate on the subgrade or pavement. Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 8 July 12, 2016 The pavement at locations for refuse dumpsters should be properly designed for the high axial loads and twisting movements of the trucks. Consideration should be given to the use of concrete pavement for the dumpster and approach areas. We recommend that the refuse collector be consulted to determine the size and thickness of the concrete pads for dumpsters. At locations where delivery truck, semi-trailers, and/or buses will be turning and maneuvering, the flexible pavement section should be designed to resist the anticipated shear stress on the pavement throughout the required pavement service life. When the traffic volumes, wheel loading conditions, and service life have been estimated, ECS can perform pavement analyses for flexible and rigid pavements for an additional fee. 5.8. Excavation Characteristics We anticipate a majority of the near-surface subgrade soils at the site can be excavated with backhoes, front-end loaders or other similar equipment using conventional means and methods. Partially weathered rock (PWR) was encountered Borings B-2, B-3, and B-10 at various depths ranging from approximately 5½ to 20 feet below existing grades. In addition, auger refusal was encountered at Boring B-2 at a depth of approximately 19 feet below existing grades. Partially weathered rock and auger refusal depths should be taken into consideration by the site civil designer when developing foundation, storm drainage, and utility plans. We would like to point out that our experience indicates rock in a weathered, boulder, and/or massive form varies erratically in location and depth within the Piedmont Geologic Province, of which Rowan County is part. Due to the variability of the Piedmont soils, there is always a potential that these materials could be encountered at shallower depths between the boring locations. The depth to, and thickness of weathered rock, rock lenses or seams, and bedrock, can vary dramatically in short distances and between boring locations; therefore, weathered rock and/or bedrock should be anticipated during construction at locations or depths, between boring locations, not encountered during this exploration. Typically, in mass excavation for general site work, materials with an N-value of 50 blows per 3 to 6 inches of penetration can be excavated with moderate to heavy effort using appropriately sized equipment, such as a large track-hoe (e.g., Caterpillar 330 with rock teeth or a D-8 bulldozer with a single ripping tooth). In confined excavations such as foundations, utility trenches, etc., removal of PWR may require use of heavy duty backhoes, pneumatic spades, or blasting. Material that exhibits less than 3 inches of penetration per 50 blows and material causing auger refusal will likely require jack hammering, blasting or drilling to facilitate removal. Due to the apparent quality of the refusal materials and local geology, we anticipate that blasting will be required in excavations that extend below the elevations indicated as “Auger Refusal” in our boring logs. Rock materials will normally require blasting for removal in all types of excavations. Any blasting in foundation excavations must be done carefully to prevent damage to the bearing materials and nearby buildings or roadways/utilities. The gradation of the material removed by ripping or blasting will likely be erratic. As noted in the Geology section of this report, the weathering process in the Piedmont can be erratic and significant variations of the depths of the more dense materials can occur in relatively short distances. In some cases, isolated boulders or thin rock seams may be present in the soil matrix. We have generally found that material that our soil drilling augers can penetrate can also be excavated with a large backhoe or ripped with a dozer mounted ripper. Weathered rock Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 9 July 12, 2016 or rock that cannot be penetrated by the mechanical auger will normally require blasting to loosen it for removal. 5.9. Cut and Fill Slopes We recommend that permanent cut slopes with less than 10 feet crest height through undisturbed residual soils be constructed at 2:1 (horizontal: vertical) or flatter. Permanent fill slopes may be constructed using engineered fill at a slope of 2.5:1 or flatter. However, a slope of 3:1 (or flatter) may be desirable to permit establishment of vegetation, safe mowing, and maintenance. The surface of cut and fill slopes should be adequately compacted. Permanent slopes should be protected using vegetation or other means to prevent erosion. A slope stability analysis should be performed on cut and fill slopes exceeding 10 feet in height to determine a slope inclination resulting in a factor of safety greater than 1.4. Upon finalization of site civil drawings, ECS should be contacted to perform slope stability analysis and determine if further exploration is necessary. The outside face of building foundations and the edges of pavements placed near slopes should be located an appropriate distance from the slope. Buildings or pavements placed at the top of fill slopes should be placed a distance equal to at least 1/3 of the height of the slope behind the crest of the slope. Buildings or pavements near the bottom of a slope should be located at least ½ of the height of the slope from the toe of the slope. Slopes with structures located closer than these limits or slopes taller than the height limits indicated should be specifically evaluated by the geotechnical engineer and may require approval from the building code official. Temporary slopes in confined or open excavations should perform satisfactorily at inclinations of 2H:1V. Excavations should comply with the requirements of OSHA 29CFR, Part 1926, Subpart P, "Excavations" and its appendices, as well as other applicable codes. This document states that the contractor is solely responsible for the design and construction of stable, temporary excavations. The excavations should not only be in accordance with current OSHA excavation and trench safety standards but also with applicable Local, State and Federal regulations. The contractor should shore, slope or bench the excavation sides when appropriate. Site safety is the sole responsibility of the contractor, who shall also be responsible for the means, methods and sequencing of construction operations. Appropriately sized ditches should run above and parallel to the crest of all permanent slopes to divert surface runoff away from the slope face. To aid in obtaining proper compaction on the slope face, the fill slopes should be overbuilt with properly compacted structural fill and then excavated back to the proposed grades. 6. CONSTRUCTION CONSIDERATIONS 6.1. Site Preparation Prior to construction, the proposed construction area should be stripped of all topsoil, organic material, CH soils as previously discussed, and other soft or unsuitable material. Upon completion of these razing and stripping operations, the exposed subgrade in areas to receive fill should be proofrolled with a loaded dump truck or similar pneumatic-tired vehicle having a loaded weight of approximately 25 tons. After excavation, the exposed subgrades in cut areas should be similarly proofrolled. Proofrolling operations should be performed under the observation of a geotechnical engineer or his authorized representative. The proofrolling should consist of two (2) complete passes of the exposed areas, with each pass being in a direction perpendicular to the preceding one. Any Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 10 July 12, 2016 areas which deflect, rut or pump during the proofrolling, and fail to be remedied with successive passes, should be undercut to suitable soils and backfilled with compacted fill. The ability to dry wet soils, and therefore the ability to use them for fill, will likely be enhanced if earthwork is performed during summer or early fall. If earthwork is performed during winter or after appreciable rainfall then subgrades may be unstable due to wet soil conditions, which could increase the amount of undercutting required. Drying of wet soils, if encountered, may be accomplished by spreading and disking or by other mechanical or chemical means. 6.2. Fill Material and Placement The project fill should be soil that has less than five percent organic content and a liquid limit and plasticity index less than 50 and 30, respectively. Soils with Unified Soil Classification System group symbols of SP, SW, SM, SC, and ML are generally suitable for use as project fill. Soils with USCS group symbol of CL that meet the restrictions for liquid limit and plasticity index are also suitable for use as project fill. Soils with USCS group symbol of MH or CH (high elasticity or plasticity soil) or corrosive soils are generally not suitable for use as project fill. The fill should exhibit a maximum dry density of at least 90 pounds per cubic foot, as determined by a standard Proctor compaction test (ASTM D 698). We recommend that moisture control limits of -3 to +2 percent of the optimum moisture content be used for placement of project fill with the added requirement that fill soils placed wet of optimum remain stable under heavy pneumatic-tired construction traffic. During site grading, some moisture modification (drying and/or wetting) of the onsite soils will likely be required. Project fill should be compacted to at least 95 percent of its standard Proctor maximum dry density except within 24 inches of finished soil subgrade elevation beneath slab-on-grade and pavements. Within the top 24 inches of finished soil subgrade elevation beneath slab on grade and pavements, the approved project fill should be compacted to at least 100 percent of its standard Proctor maximum dry density. Aggregate base course (ABC) stone should be compacted to 95 percent of modified Proctor maximum dry density. However, for isolated excavations around footing locations or within utility excavations, a hand tamper will likely be required. ECS recommends that field density tests be performed on the fill as it is being placed, at a frequency determined by an experienced geotechnical engineer, to verify that proper compaction is achieved. The maximum loose lift thickness depends upon the type of compaction equipment used. The table below provides maximum loose lifts that may be placed based on compaction equipment. LIFT THICKNESS RECOMMENDATIONS Equipment Maximum Loose Lift Thickness, in. Large, Self-Propelled Equipment (CAT 815, etc.) 8 Small, Self-Propelled or Remote Controlled (Rammax, etc.) 6 Hand Operated (Plate Tamps, Jumping Jacks, Wacker- Packers) 4 ECS recommends that fill operations be observed and tested by an engineering technician to determine if compaction requirements are being met. The testing agency should perform a sufficient number of tests to confirm that compaction is being achieved. For mass grading operations we recommend a minimum of one density test per 2,500 SF per lift of fill placed or Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 11 July 12, 2016 per 1 foot of fill thickness, whichever results in more tests. When dry, the majority of the site soil should provide adequate subgrade support for fill placement and construction operations. When wet, the soil may degrade quickly with disturbance from construction traffic. Good site drainage should be maintained during earthwork operations to prevent ponding water on exposed subgrades. We recommend at least one test per 1 foot thickness of fill for every 100 linear ft of utility trench backfill. Where fill will be placed on existing slopes, we recommend that benches be cut in the existing slope to accept the new fill. Fill slopes should be overbuilt and then cut back to expose compacted material on the slope face. While compacting adjacent to below-grade walls, heavy construction equipment should maintain a horizontal distance of 1(H):1(V). If this minimum distance cannot be maintained, the compaction equipment should run perpendicular, not parallel to, the long axis of the wall. 6.3. Foundation Construction & Testing Foundation excavations should be tested to confirm adequate bearing prior to installation of reinforcing steel or placement of concrete. Unsuitable soils should be undercut to firm soils and the undercut excavations should be backfilled with compacted controlled fill. Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a time; therefore, foundation concrete should be placed the same day that foundations are excavated. If the bearing soils are softened by surface water intrusion or exposure, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. If the excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, a 1- to 3-inch thick "mud mat" of "lean" concrete may be placed on the bearing surface to protect the bearing soils. The mud mat should not be placed until the bearing soils have been tested for adequate bearing capacity. Foundations undercut should be backfilled with engineered fill. If lean concrete is placed within the undercut zone, the foundation footprint does not require oversizing. However, if soil or ABC stone is used in lieu of lean concrete, the foundation footprint should be oversized on a 1V:1H scale. We recommend testing shallow foundations to confirm the presence of foundation materials similar to those assumed in the design. We recommend the testing consist of hand auger borings with Dynamic Cone Penetrometer (DCP) testing performed by an engineer or engineering technician. 7. GENERAL COMMENTS The borings performed at this site represent the subsurface conditions at the location of the borings only. Due to the prevailing geology, changes in the subsurface conditions can occur over relatively short distances that have not been disclosed by the results of the borings performed. Consequently, there may be undisclosed subsurface conditions that require special treatment or additional preparation once these conditions are revealed during construction. Our evaluation of foundation support conditions has been based on our understanding of the site and project information and the data obtained in our exploration. The general subsurface conditions utilized in our foundation evaluation have been based on interpolation of subsurface data between and away from the test holes. If the project information is incorrect or if the structure locations (horizontal or vertical) and/or dimensions are changed, please contact us so that our recommendations can be reviewed. The discovery of any site or subsurface conditions during construction which deviate from the data outlined in this exploration should be reported to Report of Subsurface Exploration Mr. Scott Shelton Summit Corporate Center RowanWORKS Salisbury, North Carolina ECS Project No. 08-11761-A Page 12 July 12, 2016 us for our evaluation. The assessment of site environmental conditions for the presence of pollutants in the soil, rock, and groundwater of the site was beyond the scope of this exploration. The recommendations outlined herein should not be construed to address moisture or water intrusion effects after construction is completed. Proper design of landscaping, surface and subsurface water control measures are required to properly address these issues. In addition, proper operation and maintenance of building systems is required to minimize the effects of moisture or water intrusion. The design, construction, operation, and maintenance of waterproofing and dampproofing systems are beyond the scope of services for this project. Site Vicinity Map Boring Location Diagram Borelogs ASFE Documents APPENDIX 0 5 10 15 20 25 30 860 855 850 845 840 835 830 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 14 16 18 16 18 14 Topsoil Depth [3"] (CL) RESIDUUM - SANDY CLAY, Tan, Moist, Medium Stiff (ML) SANDY SILT, Trace Sand, Gray Tan to Orange Tan, Moist, Very Stiff to Stiff (ML) SANDY SILT, Trace Sand, Gray Orange Tan, Moist, Medium Stiff to Stiff END OF BORING @ 20.0' 2 3 4 5 7 10 5 5 8 2 2 3 3 4 6 2 4 7 7 17 13 5 10 11 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-1 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 17.7' WL(SHW)WL(ACR) 17.0 BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT860 1 OF 1 0 5 10 15 20 25 30 845 840 835 830 825 820 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 10 18 8 12 18 18 5 6 4 Topsoil Depth [3"] (SM) RESIDUUM - SILTY FINE TO MEDIUM SAND, Brown, Moist, Medium Dense (ML) SANDY SILT, Red Gray, Moist, Very Hard (SM) SILTY FINE SAND, Gray Orange, Moist, Very Dense (SM PWR) PARTIALLY WEATHERED ROCK SAMPLED AS SILTY MEDIUM TO COARSE SAND, Gray (SM) RESIDUUM SILTY MEDIUM TO COARSE SAND, Orange Gray, Moist, Very Dense (SM PWR) PARTIALLY WEATHERED ROCK SAMPLED AS SILTY MEDIUM TO COARSE SAND, Gray Orange AUGER REFUSAL @ 19.0' 5 5 6 11 26 39 33 44 50 50/5 50/5 34 42 50 50/4 50/4 11 65 94 100+ 92 100+ CLIENT RowanWORKS JOB # 08:11761-A BORING # B-2 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 15.8' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT846 1 OF 1 0 5 10 15 20 25 30 845 840 835 830 825 820 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 16 15 14 8 18 18 9 15 10 Topsoil Depth [3.5"] (SM) RESIDUUM - SILTY FINE TO MEDIUM SAND, Brown, Moist, Medium Dense (CH) PLASTIC CLAY, Gray Orange, Moist, Stiff (CL) SANDY CLAY, Orange Gray, Moist, Very Stiff (SM PWR) PARTIALLY WEATHERED ROCK SAMPLED AS SILTY MEDIUM TO COARSE SAND, Gray Orange to Brown Orange END OF BORING @ 20.0' 5 6 8 4 6 8 6 9 13 36 50/5 50/5 36 44 50/3 28 50/4 50/4 14 14 22 100+ 100+ 100+ CLIENT RowanWORKS JOB # 08:11761-A BORING # B-3 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 16.9' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT847 1 OF 1 0 5 10 15 20 25 30 865 860 855 850 845 840 835 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 16 18 16 8 16 18 Topsoil Depth [2.5"] (SM) RESIDUUM - SILTY FINE SAND, Brown, Moist, Medium Dense (CL) SANDY CLAY, Brown Gray, Moist, Very Stiff (ML) SANDY SILT, Gray Brown, Moist, Very Hard to Hard (SM) SILTY FINE SAND, Brown White, Moist, Medium Dense END OF BORING @ 20.0' 5 8 4 4 10 17 16 26 38 12 21 20 8 11 15 8 10 13 12 27 64 41 26 23 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-4 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 16.9' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT865 1 OF 1 0 5 10 15 20 25 30 870 865 860 855 850 845 840 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 10 14 10 18 16 18 Topsoil Depth [3"] (CL) RESIDUUM - SANDY CLAY, Brown Red, Moist, Very Stiff to Stiff (ML) SANDY SILT, Brown Gray, Moist, Very Stiff (SM) SILTY FINE SAND, Brown Orange, Moist, Medium Dense END OF BORING @ 20.0' 6 9 11 4 6 8 6 10 11 4 6 10 8 11 13 5 12 17 20 14 21 16 24 29 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-5 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 16.5' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT870 1 OF 1 0 5 10 15 20 25 30 800 795 790 785 780 775 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 16 18 16 18 18 18 Topsoil Depth [2.5"] (CL) RESIDUUM - SANDY CLAY, Brown Red, Moist, Very Stiff (ML) SANDY SILT, Gray Red to Tan Gray, Moist, Hard to Very Stiff (ML) SANDY SILT, Tan Orange Gray, Moist, Medium Stiff to Soft (ML) SANDY SILT, Orange Gray, Moist, Stiff END OF BORING @ 20.0' 8 9 13 10 15 16 6 8 11 3 3 5 2 2 2 2 4 5 22 31 19 8 4 9 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-6 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 17.1' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT803 1 OF 1 0 5 10 15 20 25 30 855 850 845 840 835 830 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 12 14 10 16 18 14 Topsoil Depth [3.5"] (CL) RESIDUUM - SANDY CLAY, Gray Brown, Moist, Soft (CL) SANDY CLAY, Orange Brown, Moist, Stiff to Very Stiff (ML) SANDY SILT, Gray Orange Tan, Moist, Stiff END OF BORING @ 20.0' 1 2 2 5 6 9 7 11 15 3 5 7 5 5 8 4 5 5 4 15 26 12 13 10 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-7 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 17.5' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT859 1 OF 1 0 5 10 15 20 25 30 855 850 845 840 835 830 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 6 14 18 18 18 18 Topsoil Depth [2"] (SM) RESIDUUM - SILTY FINE SAND, Brown, Moist, Medium Dense (SM) SILTY FINE SAND, Brown, Moist, Very Dense (SM) SILTY FINE SAND, Brown, Moist, Medium Dense (ML) SANDY SILT, Brown, Moist, Stiff END OF BORING @ 20.0' 5 5 7 17 23 29 14 20 31 7 9 14 4 5 8 3 5 7 12 52 51 23 13 12 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-8 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 17.6' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT859 1 OF 1 0 5 10 15 20 25 30 855 850 845 840 835 830 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 18 18 18 18 2 14 10 18 10 16 Topsoil Depth [2.5"] (SM) RESIDUUM - SILTY FINE SAND, Brown, Moist, Medium Dense (ML) SANDY SILT, Brown, Moist, Very Stiff (SM) SILTY FINE SAND, Brown, Moist, Very Dense (ML) SANDY SILT, Tan, Moist, Stiff (SM) SILTY MEDIUM TO COARSE SAND, Tan, Moist, Medium Dense (ML) SANDY SILT, Orange Brown, Moist, Very Stiff END OF BORING @ 20.0' 6 11 12 6 10 14 16 27 37 4 5 9 11 14 14 5 8 11 23 24 64 14 28 19 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-9 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 17.2' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT858 1 OF 1 0 5 10 15 20 25 30 860 855 850 845 840 835 S-1 S-2 S-3 S-4 S-5 S-6 SS SS SS SS SS SS 18 18 17 18 18 18 2 18 17 18 18 18 Topsoil Depth [2"] (NO RECOVERY), Cuttings - (SC) CLAYEY FINE SAND, Brown, Moist, Medium Dense (SM) RESIDUUM - SILTY FINE SAND, Tan, Moist, Very Dense (ML PWR) PARTIALLY WEATHERED ROCK SAMPLED AS SANDY SILT, Tan (ML) RESIDUUM SANDY SILT, Orange Brown, Moist, Very Stiff (SM) SILTY FINE SAND, Brown White Orange, Moist, Medium Dense to Dense END OF BORING @ 20.0' 8 8 8 10 20 36 20 32 50/5 7 11 15 6 8 11 7 13 19 16 56 100+ 26 19 32 CLIENT RowanWORKS JOB # 08:11761-A BORING # B-10 SHEET PROJECT NAME Summit Corporate Center - GEO ARCHITECT-ENGINEER SITE LOCATION Julian Road, Salisbury, Rowan County, NC NORTHING EASTING STATION THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL. WL GNE WS WD BORING STARTED 06/29/16 CAVE IN DEPTH @ 15.1' WL(SHW)WL(ACR) GNE BORING COMPLETED 06/29/16 HAMMER TYPE Manual WL RIG ATV FOREMAN Cody DRILLING METHOD ATV on TracksDRILLING METHOD ATV on TracksDEPTH (FT)SAMPLE NO.SAMPLE TYPESAMPLE DIST. (IN)RECOVERY (IN)SURFACE ELEVATION DESCRIPTION OF MATERIAL WATER LEVELSELEVATION (FT)BLOWS/6"10 20 30 40 50+ 20%40%60%80%100% 1 2 3 4 5+ ENGLISH UNITS BOTTOM OF CASING LOSS OF CIRCULATION CALIBRATED PENETROMETER TONS/FT2 PLASTIC LIMIT % WATER CONTENT % LIQUID LIMIT % ROCK QUALITY DESIGNATION & RECOVERY RQD%REC.% STANDARD PENETRATION BLOWS/FT863 1 OF 1 Major Divisions Group Symbols Typical Names Laboratory Classification Criteria GW Well graded gravels, gravel- sand mixtures, little or no fines Cu=D60/D10 greater than 4 Cc= (D30)2/(D10 x D60) between 1 and 3 Clean Gravels (Little or no fines) GP Poorly graded gravels, gravel- sand mixtures, little or no fines Not meeting all gradation requirements for GW d GMa u Silty Gravels, gravel-sand-silt mixtures Atterberg limits below “A” line or P.I. less than 4 Gravels (More than half of coarse fraction is larger than No. 4 sieves size) Gravels with fines GC Clayey Gravels, gravel-sand- clay mixtures Atterberg limits above “A” line with P.I. greater than 7 Above “A” line with P.I. between 4 and 7 are borderline cases requiring use of dual symbols SW Well-graded sands, gravelly sands, little or no fines Cu=D60/D10 greater than 6 Cc= (D30)2/(D10 x D60) between 1 and 3 Clean Sands (Little or no fines) SP Poorly graded sands, gravelly sands, little or no fines Not meeting all gradation requirements for SW d SMa u Silty sands, sand-silt mixtures Atterberg limits below “A” line or P.I. less than 4 Coarse-Grained Soils (More than half of the material is larger than No. 200 sieve size) Sands (More than half of coarse fraction is smaller than No. 4 sieve size) Sands with fines SC Clayey sands, sand-clay mixtures Determine percentages of sand and gravel from grain size curve Depending on the percentage of the fines (fraction smaller than No. 200 sieve size), Coarse grained soils are classified as follows: Less than 5% GW, GP, SW, SP More than 12% GM, GC, SM, SC 5 to 12% Borderline cases requiring dual symbolsb Atterberg limits above “A” line with P.I. greater than 7 Limits plotting in hatched zone with P.I. between 4 and 7 are borderline cases requiring use of dual symbols ML Inorganic silts and very fine sands, rock flour, silty or clayey fine sands, or clayey silts with slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays Silts and Clays (Liquid Limit less than 50) OL Organic silts and organic silty clays of low plasticity MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts CH Inorganic clays of high plasticity, fat clays Silts and Clays (Liquid Limit greater than 50) OH Organic clays of medium to high plasticity, organic silts Fine-Grained Soils (More than half of material is smaller than No. 200 sieve) Highly Organic Soils Pt Peat and other highly organic soils Reference: Winterkorn & Fang, 1975 (ASTM D-2487) aDivision of GM and SM groups into subdivision of d and u are for road and airfields only. Subdivision is based on Atterberg limits; suffix d used when L.L. is 28 or less and the P.I. is 6 or less; the suffix u is used when L.L. is greater that 28. bBorderline classifications, used for soils possessing characteristics of two groups, are designated by combinations of group symbols. For example: GW-GC, well-graded gravel-sand mixture with clay binder. UNIFIED SOIL CLASSIFICATION SYSTEM 1812 CENTER PARK DRIVE SUITE D CHARLOTTE, NC 28217 704/525-5152 FAX/704-357-0023 REFERENCE NOTES FOR BORING LOGS I. Drilling Sampling Symbols SS Split Spoon Sampler ST Shelby Tube Sampler RC Rock Core, NX, BX, AX PM Pressuremeter DC Dutch Cone Penetrometer RD Rock Bit Drilling BS Bulk Sample of Cuttings PA Power Auger (no sample) HSA Hollow Stem Auger WS Wash sample REC Rock Sample Recovery % RQD Rock Quality Designation % II. Correlation of Penetration Resistances to Soil Properties Standard Penetration (blows/ft) refers to the blows per foot of a 140 lb. hammer falling 30 inches on a 2-inch OD split-spoon sampler, as specified in ASTM D 1586. The blow count is commonly referred to as the N-value. A. Non-Cohesive Soils (Silt, Sand, Gravel and Combinations) Density Relative Properties Under 4 blows/ft Very Loose Adjective Form 12% to 49% 5 to 10 blows/ft Loose With 5% to 12% 11 to 30 blows/ft Medium Dense 31 to 50 blows/ft Dense Over 51 blows/ft Very Dense Particle Size Identification Boulders 8 inches or larger Cobbles 3 to 8 inches Gravel Coarse 1 to 3 inches Medium ½ to 1 inch Fine ¼ to ½ inch Sand Coarse 2.00 mm to ¼ inch (dia. of lead pencil) Medium 0.42 to 2.00 mm (dia. of broom straw) Fine 0.074 to 0.42 mm (dia. of human hair) Silt and Clay 0.0 to 0.074 mm (particles cannot be seen) B. Cohesive Soils (Clay, Silt, and Combinations) Blows/ft Consistency Unconfined Comp. Strength Qp (tsf) Degree of Plasticity Plasticity Index Under 2 Very Soft Under 0.25 None to slight 0 – 4 3 to 4 Soft 0.25-0.49 Slight 5 – 7 5 to 8 Medium Stiff 0.50-0.99 Medium 8 – 22 9 to 15 Stiff 1.00-1.99 High to Very High Over 22 16 to 30 Very Stiff 2.00-3.00 31 to 50 Hard 4.00–8.00 Over 51 Very Hard Over 8.00 III. Water Level Measurement Symbols WL Water Level BCR Before Casing Removal DCI Dry Cave-In WS While Sampling ACR After Casing Removal WCI Wet Cave-In WD While Drilling Est. Groundwater Level Est. Seasonal High GWT The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering, without adding fluids, in a granular soil. In clay and plastic silts, the accurate determination of water levels may require several days for the water level to stabilize. In such cases, additional methods of measurement are generally applied. Important Information About Your Geotechnical Engineering Report Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes The following information is provided to help you manage your risks. Geotechnical Services Are Performed for Speciﬁ c Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the speciﬁ c needs of their clients. A geotechnical engineering study conducted for a civil engineer may not fulﬁ ll the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geo- technical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineering report without ﬁ rst conferring with the geotechnical engineer who prepared it. And no one - not even you - should apply the report for any purpose or project except the one originally contemplated. Read the Full Report Serious problems have occurred because those relying on a geotechnical engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only. A Geotechnical Engineering Report Is Based on A Unique Set of Project-Speciﬁ c Factors Geotechnical engineers consider a number of unique, project-speciﬁ c factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and conﬁ guration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engi- neer who conducted the study speciﬁ cally indicates otherwise, do not rely on a geotechnical engineering report that was: • not prepared for you, • not prepared for your project, • not prepared for the speciﬁ c site explored, or • completed before important project changes were made. Typical changes that can erode the reliability of an existing geotechnical engineering report include those that affect: • the function of the proposed structure, as when it’s changed from a parking garage to an ofﬁ ce building, or from alight industrial plant to a refrigerated warehouse, • elevation, conﬁ guration, location, orientation, or weight of the proposed structure, • composition of the design team, or • project ownership. As a general rule, always inform your geotechnical engineer of project changes - even minor ones - and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed. Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineering report whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natu- ral events, such as ﬂ oods, earthquakes, or groundwater ﬂ uctuations. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems. Most Geotechnical Findings Are Professional Opinions Site exploration identiﬁ es subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review ﬁ eld and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ-sometimes signiﬁ cantly from those indi- cated in your report. Retaining the geotechnical engineer who developed your report to provide construction observation is the most effective method of managing the risks associated with unanticipated conditions. A Report’s Recommendations Are Not Final Do not overrely on the construction recommendations included in your re- port. Those recommendations are not ﬁ nal, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can ﬁ nalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engi- neer who developed your report cannot assume responsibility or liability for the report’s recommendations if that engineer does not perform construction observation. A Geotechnical Engineering Report Is Subject to Misinterpretation Other design team members’ misinterpretation of geotechnical engineer- ing reports has resulted in costly problems. Lower that risk by having your geotechnical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and speciﬁ cations. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation. Do Not Redraw the Engineer’s Logs Geotechnical engineers prepare ﬁ nal boring and testing logs based upon their interpretation of ﬁ eld logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk. Give Contractors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make contractors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give con- tractors the complete geotechnical engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise contractors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct ad- ditional study to obtain the speciﬁ c types of information they need or prefer. A prebid conference can also be valuable. Be sure contractors have sufﬁ cient time to perform additional study. Only then might you be in a position to give contractors the best information available to you, while requiring them to at least share some of the ﬁ nancial responsibilities stemming from unantici- pated conditions. Read Responsibility Provisions Closely Some clients, design professionals, and contractors do not recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly. Geoenvironmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform a geoenviron- mental study differ signiﬁ cantly from those used to perform a geotechnical study. For that reason, a geotechnical engineering report does not usually re- late any geoenvironmental ﬁ ndings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own geoenvironmental in- formation, ask your geotechnical consultant for risk management guidance. Do not rely on an environmental report prepared for someone else. Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, op- eration, and maintenance to prevent signiﬁ cant amounts of mold from grow- ing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, a number of mold prevention strategies focus on keeping building surfaces dry. While groundwater, wa- ter inﬁ ltration, and similar issues may have been addressed as part of the geotechnical engineering study whose ﬁ ndings are conveyed in-this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufﬁ cient to prevent mold from growing in or on the struc- ture involved. Rely on Your ASFE-Member Geotechnical Engineer For Additional Assistance Membership in ASFE/The Best People on Earth exposes geotechnical engi- neers to a wide array of risk management techniques that can be of genuine beneﬁ t for everyone involved with a construction project. Confer with your ASFE-member geotechnical engineer for more information. 8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone:’ 301/565-2733 Facsimile: 301/589-2017 e-mail: info@asfe.org www.asfe.org Copyright 2004 by ASFE, Inc. Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly prohibited, except with ASFE’s speciﬁ c written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of ASFE, and only for purposes of scholarly research or book review. Only members of ASFE may use this document as a complement to or as an element of a geotechnical engineering report. Any other ﬁ rm, individual, or other entity that so uses this document without being anASFE member could be committing negligent or intentional (fraudulent) misrepresentation. IIGER06045.0M The Best People on Earth