Fieldcrest Pedestrian Bridge Fieldcrest Road Green Oak Township, Michigan

Transcription

1 Report on Geotechnical Investigation Fieldcrest Pedestrian Bridge Fieldcrest Road Green Oak Township, Michigan Latitude N Longitude W Prepared for: Civil Engineering Solutions, Inc. P.O. Box # Grand River Avenue New Hudson, Michigan 815 September 2, 2015

2 September 2, 2015 Mr. Fadi Khalil, P.E. Civil Engineering Solutions, Inc. P.O. Box # Grand River Avenue New Hudson, Michigan 815 Re: Report on Geotechnical Investigation Fieldcrest Pedestrian Bridge Fieldcrest Road Green Oak Township, Michigan Dear Mr. Khalil: We have completed the geotechnical investigation for the proposed Fieldcrest Pedestrian Bridge located in Green Oak Township, Michigan. This report presents the results of our field investigation, observations, and analyses, and our recommendations for subgrade preparation, foundation design, and construction considerations as they relate to the geotechnical conditions at the site. We appreciate the opportunity to be of service to Civil Engineering Solutions, Inc. and look forward to discussing the recommendations presented herein. In the meantime, if you have any questions regarding this report or any other matter pertaining to the project, please call us. Sincerely, G2 Consulting Group, LLC Amy L. Schneider, P.E. Project Manager Noel J. Hargrave-Thomas, P.E. Principal ALS/NJHT/ljv Enclosures

3 September 2, 2015 Page 1 EXECUTIVE SUMMARY We understand current plans include construction of a new pedestrian bridge spanning the Huron River along the west side of Fieldcrest Road in Green Oak Township, Michigan. The bridge is prefabricated by Continental Bridge and will be 8 feet wide by 175 feet in length. Approximately inches of sand fill are present at the boring locations. An approximately 12 inch layer of topsoil is present in boring B-1 below the sand fill. Loose to medium compact gravelly sand fill and silty sand fill underlie the topsoil in boring B-1 extending to an approximate depth of feet and the upper sand fill in boring B-2 extending to an approximate depth of 12 feet. Native very loose silty sand underlies the fill in boring B-2 and extends to an approximate depth of 1 feet. In general, native loose to medium compact silty sand and sand are present below the fill in boring B-1 and the loose silty sand in boring B-2 and extend to the explored depth of 0 feet with the exception of a layer of medium silty clay in boring B-1 extending from an approximate depth of 8 to 11 feet and medium clayey silt in boring B-2 from an approximate depth of 22 to 2 feet. Groundwater was encountered during drilling operations at an approximate depth of 12 feet in boring B-1 and -1/2 feet in boring B-2. Upon completion of drilling and following removal of the augers, a wet cave of the boreholes was measured at approximate depths of 10 and 7-1/2 feet in borings B-1 and B-2, respectively. We understand the proposed pedestrian bridge was designed to be supported on concrete abutment foundations bearing at an approximate elevation of 81-1/2 feet with a design bearing capacity of 2,900 pounds per square foot (psf); however, this bearing capacity is not achievable on the existing soils. Therefore, based on the encountered soil conditions, we recommend the bridge be designed to be supported on straight shaft drilled piers or helical anchors. Drilled pier foundations should be designed per the recommended parameters in the Foundation Recommendations section of this report. Based on the bridge loading and subsurface conditions, we anticipate the drilled piers will be on the order of - 1/2 to foot in diameter and bear at an approximate depths ranging from 17 to 2 feet below abutment bearing elevation of approximately 81-1/2 feet. Following construction of the drilled piers, the concrete abutment can be constructed, with the piers embedded, for support of the bridge structure. Alternatively, the bridge can be supported on helical piers. Helical piers consist of metal plates formed into the shape of a helix attached to a long metal shaft. Installation is completed by applying a torque to the anchor until it is screwed into the underlying bearing soils. The concrete abutment will then be constructed to support the bridge structure and provide any lateral or uplift loads, as designed. The helical piers, once embedded in the concrete abutment, will transfer the structure loads into the deeper underlying soils. The helical piers can be designed utilizing the bearing capacities presented in the Foundation Recommendation section of this report. The helixes should be placed in descending diameter order. The nominal vertical spacing between the helix plates should be three times the diameter of the next lower helix. The tops of the helical piers should be embedded a minimum of inches into the bottoms of the concrete grade beams. Abutments should extend a minimum of -1/2 feet below finished grade for protection against frost heave. Caving and sloughing of the granular soils will occur during drilled pier excavation operations. In addition, groundwater will be encountered at approximate elevations ranging from 85 to 80-1/2 feet. Therefore, the contractor should come to the site prepared to use temporary steel casing, drilling mud, and water, as necessary, to maintain a stable excavation during construction operations. A minimum drilling mud head of feet above the static groundwater level should be maintained to insure a stable excavation. Caving and sloughing of the native and fill granular soils should be anticipated during excavation for bridge abutments. The contractor should be prepared to over excavate and form the abutments. The sides of the foundations should be constructed straight and vertical to reduce the risk of frozen soil adhering to the concrete and raising the foundation. Do not consider this summary separate from the entire text of this report, with all the conclusions and qualifications mentioned herein. Details of our analysis and recommendations are discussed in the following sections and in the Appendix of this report.

4 September 2, 2015 Page 2 PROJECT DESCRIPTION We understand current plans include construction of a new pedestrian bridge spanning the Huron River along the west side of Fieldcrest Road in Green Oak Township, Michigan. The bridge is prefabricated by Continental Bridge and will be 8 feet wide by 175 feet in length. The bridge is currently designed to bear on concrete abutments designed for a bearing capacity of 2,900 psf. In addition, a pedestrian asphalt path will be constructed leading to the bridge. No design information regarding the path is discussed in this report. The proposed bottom of bridge elevation at the abutment location is feet. The existing elevation at the abutment location is approximately 8-1/2 feet on the south side and 85 feet on the north side. Based on the Continental Bridge drawings, Sheet C., dated July 2, 2015 (Revision 2), the bridge has the following vertical loads at each base plate - a dead load of kips, a uniform live load of kips, and a vehicle load of kips. If proposed grades are different from our assumptions, G2 must be notified so we can review the recommendations presented in this report. SCOPE OF SERVICES Field operations, laboratory testing, and engineering report preparation were performed under the direction and supervision of a licensed professional engineer. Our services were performed according to generally accepted standards and procedures in the practice of geotechnical engineering in this area. Our scope of services for this project is as follows: 1. We drilled two soil borings for the proposed bridge extending to a depth of 0 feet each. 2. We performed laboratory testing on representative samples obtained from the soil borings. Laboratory testing included visual engineering classification, natural moisture content, organicmatter content (loss-on-ignition/loi), dry density, and unconfined compressive strength determinations.. We prepared this engineering report. Our report includes recommendations regarding the allowable soil bearing capacity, foundation design parameters, estimated settlement, and construction considerations related to the foundation construction. FIELD OPERATIONS G2, in conjunction with Civil Engineering Solutions, Inc. (CEC), selected the number, depth, and location of the soil borings. The soil borings were staked in the field by the drillers prior to our drilling operations. The borings were offset from the proposed abutment locations due to access issues associated with the steep grades to the river and vegetation limiting access. The approximate soil boring locations are shown on the Soil Boring Location Plan, Plate No. 1. Ground surface elevations at the soil boring locations were interpolated from the Fieldcrest Pedestrian Bridge Profile prepare by CES, dated July 1, 2015 (Revision 2). The soil borings were drilled using a truck-mounted rotary drilling rig. Continuous-flight, 2-1/ inch inside diameter hollow-stem augers were used to advance the boreholes. Soil samples were obtained at intervals of 2-1/2 feet within the upper 10 feet and at 5 foot intervals below that depth. These samples were obtained by the Standard Penetration Test Method (ASTM D 158), which involves driving a 2-inch diameter split-spoon sampler into the soil with a 10-pound weight falling 0 inches. The sampler is generally driven three successive -inch increments, with the number of blows for each increment recorded. The number of blows required to advance the sampler the last 12 inches is termed the Standard Penetration Resistance (N). Blow counts for each six-inch increment and resulting N-values are presented on the individual soil boring logs.

5 September 2, 2015 Page The soil samples were placed in sealed containers in the field and brought to our laboratory for testing and classification. During field operations, drilling representatives maintained soil boring logs of the subsurface conditions, including changes in stratigraphy and observed groundwater levels. The final boring logs are based on the field logs supplemented by laboratory soil classification and test results. The soil borings were backfilled with auger cuttings upon completion of drilling operations. LABORATORY TESTING Representative soil samples were subjected to laboratory testing to determine soil parameters pertinent to foundation design and site preparation. An experienced geotechnical engineer classified the samples in general conformance with the Unified Soil Classification System. Laboratory testing included natural moisture content, dry density, organic matter content, and unconfined compressive strength determinations. The organic matter content (loss-on-ignition/loi) of representative samples was determined in accordance with ASTM Test Method D 297, Standard Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. The unconfined compressive strengths were determined by ASTM Test Method D 21 and a spring loaded hand penetrometer. Per ASTM Test Method D 21 Standard Test Method for Unconfined Compressive Strength of Cohesive Soil, the unconfined compressive strength of cohesive soils is determined by axially loading a small cylindrical soil sample under a slow rate of strain. The unconfined compressive strength is defined as the maximum stress applied to the soil sample before shear failure. If shear failure does not occur prior to a total strain of 15 percent, the unconfined compressive strength is defined as the stress at a total strain of 15 percent. The hand penetrometer estimates the unconfined compressive strength to a maximum of -1/2 tons per square foot (tsf) by measuring the resistance of the soil sample to the penetration of a calibrated spring loaded cylinder. The results of the laboratory tests are indicated on the boring logs at the depths the samples were obtained. The unconfined compressive strengths are also presented on the Unconfined Compressive Strength Test Sheet, Figure No.. We will hold the soil samples for 0 days from the date of this report, after which time they will be discarded. If you would like to retain the samples beyond that date, please let us know. SITE CONDITIONS The proposed bridge will be constructed over the Huron River between U-2 and Fieldcrest Road in Green Oak Township, Michigan. The area is currently covered with grass and small trees. A metal guardrail and chain link fence extends along the west side of Fieldcrest Road. The grades slope downward from the ends of the guardrail to the river, with elevations ranging from approximately 88 feet at the top to 81 feet at the waters edge. SOIL CONDITIONS Approximately inches of sand fill are present at the boring locations. An approximately 12 inch layer of topsoil is present in boring B-1 below the sand fill. Gravelly sand fill and silty sand fill underlie the topsoil in boring B-1 extending to an approximate depth of feet and the upper sand fill in boring B-2 extending to an approximate depth of 12 feet. In general, native silty sand and sand are present below the fill and extend to the explored depth of 0 feet with the exception of a layer of silty clay in boring B-1 extending from an approximate depth of 8 to 11 feet and clayey silt in boring B-2 from an approximate depth of 22 to 2 feet. The gravelly sand fill and silty sand fill are loose to medium compact with Standard Penetration Test N- values ranging between 8 to 15 blows per foot. The native silty sand in boring B-2 is very loose in compactness from an approximate depth of 12 to 1 feet with an N-value of blows per foot. The remainder of the native granular soils are loose to medium compact with N-values ranging from to 28

6 September 2, 2015 Page blows per foot. The silty clay and clayey silt are medium in consistency with natural moisture contents of 21 and 2 percent, a dry density of 102 pcf, and unconfined compressive strengths of 1,000 and 1,10 psf. The stratification depths shown on the soil boring logs represent the soil conditions at the boring locations. Variations may occur away from the boring locations. Additionally, the stratigraphic lines represent the approximate boundary between soil types. The transition may be more gradual than what is shown. We have prepared the boring logs on the basis of the field logs of soils encountered supplemented by laboratory classification and testing. The Soil Boring Location Plan, Plate No. 1, Soil Boring Logs, Figure Nos. 1 and 2, and Unconfined Compressive Strength Test, Figure No., are presented in the Appendix. The soil profiles described above are generalized descriptions of the conditions encountered at the boring locations. General Notes Terminology defining the nomenclature used on the soil boring logs and elsewhere in this report is presented on Figure No.. GROUNDWATER CONDITIONS Groundwater was encountered during drilling operations at an approximate depth of 12 feet in boring B-1 and -1/2 feet in boring B-2. Upon completion of drilling and following removal of the augers, a wet cave of the boreholes was measured at approximate depths of 10 and 7-1/2 feet in borings B-1 and B-2, respectively. Fluctuations in perched and long term groundwater levels should be anticipated due to seasonal variations and following periods of prolonged precipitation. SITE PREPARATION On the basis of available data, it appears a moderate amount of earthwork will be required to achieve final design grades and construct the bridge. Earthwork operations are anticipated to consist of removing vegetation, topsoil, and trees, excavating for the structure foundations, and preparing the subgrade soils for pavement slab support. We recommend all earthwork operations be performed under adequate specifications and properly monitored in the field. At the start of earthwork operations, the existing vegetation, topsoil, and trees should be removed in their entirety from the proposed structure and pavement areas. We recommend the subgrade soil be thoroughly proof compacted for support of the proposed pathway with a 10-ton vibratory roller making a minimum of 10 passes in each of two perpendicular directions. Any unstable or unsuitable areas noted during proof compacting operations should be undercut and replaced with engineered fill. Engineered fill should be free of organic matter, frozen soil, clods, or other harmful material. The fill should be placed in uniform horizontal layers that are not more than 9 inches in loose thickness. The engineered fill should be compacted to achieve a density of at least 95 percent of the maximum dry density as determined by the Modified Proctor compaction test (ASTM D 1557). All engineered fill material should be placed and compacted at approximately the optimum moisture content. Frozen material should not be used as fill, nor should fill be placed on a frozen subgrade. We recommend using granular engineered fill within confined areas such as adjacent to foundation walls. Granular engineered fill is generally more easily compacted than cohesive soils within these confined areas. Additionally, the proper placement and compaction of backfill within these areas is imperative to provide adequate support for overlying pavements. FOUNDATION RECOMMENDATIONS We understand the proposed pedestrian bridge was designed to be supported on concrete abutment foundations bearing at an approximate elevation of 81-1/2 feet with a design bearing capacity of 2,900

7 September 2, 2015 Page 5 psf; however, this bearing capacity is not achievable on the existing soils. Therefore, based on the encountered soil conditions, we recommend the bridge be designed to be supported on straight shaft drilled piers or helical anchors. Following completion of the drilled pier foundations for bearing support, the abutment can be constructed for support of the bridge structure. Drilled pier foundations should be designed per the recommended parameters in the Foundation Recommendations section of this report. Based on the bridge loading and subsurface conditions, we anticipate the drilled piers will be on the order of -1/2 to foot in diameter and bear at an approximate depths ranging from 17 to 2 feet below abutment bearing elevation of approximately 81-1/2 feet. We recommend the following design parameters be utilized. The allowable skin friction and bearing capacity parameters are based on a factor of safety of. Soil Boring B-1 (South Drilled Piers) Depth (Elevation) Allowable Skin Friction (psf) Allowable Bearing Pressure (psf) 88 to to to , to ,500 *Neglect top feet below finished grade for frost penetration Soil Boring B-2 (North Drilled Piers) Depth (Elevation) Allowable Skin Friction (psf) Allowable Bearing Pressure (psf) 87 to to to to to , to ,500 *Neglect top feet below finished grade for frost penetration Alternatively, the bridge can be supported on helical piers. Helical piers consist of metal plates formed into the shape of a helix attached to a long metal shaft. Installation is completed by applying a torque to the anchor until it is screwed into the underlying bearing soils. The concrete abutment will then be constructed to support the bridge structure and provide any lateral or uplift loads, as designed. The helical piers, once embedded in the concrete abutment, will transfer the structure loads into the deeper underlying soils. The helical piers can be designed utilizing the above stated bearing capacities. The helixes should be placed in descending diameter order. The nominal vertical spacing between the helix plates should be three times the diameter of the next lower helix. The tops of the helical piers should be embedded a minimum of inches into the bottoms of the concrete grade beams. Abutments should extend a minimum of -1/2 feet below finished grade for protection against frost heave. If requested, helix sizes and capacities can be provided for an additional fee. G2 can provide a list of vendors that specialize in helical anchor pier installation upon request. If the recommendations outlined in this report are adhered to, total and differential settlements for the completed structure should be within 1 inch and 1/2 inch, respectively. We expect settlements of these magnitudes are within tolerable limits for the type of structure proposed.

8 September 2, 2015 Page CONSTRUCTION CONSIDERATIONS Drilled Piers Caving and sloughing of the granular soils will occur during drilled pier excavation operations. In addition, groundwater was encountered at approximate elevations ranging from 85-1/2 to 80 feet; however, it should be noted the borings were performed approximately 1-1/2 feet higher in elevation than the grade at the proposed abutment. Therefore, groundwater may be encountered at shallower depths. Due to the groundwater and granular soil, the contractor should come to the site prepared to use temporary telescoped casing, drilling mud, and water, as necessary, to maintain a stable excavation. A minimum drilling mud head of feet should be maintained above the static groundwater level to maintain a stable excavation during construction operations. When drilling is completed to the design depth, reinforcing steel should be set and concrete placed by tremie method until a positive head of concrete has been established within the casing. This positive concrete head must be maintained while pulling the casing to prevent the infiltration of loose soil and groundwater into the fresh concrete. After concrete has been placed to an appropriate grade, the casing may be removed and concrete placement operations completed. To reduce lateral movement of the drilled piers, the contractor must place the concrete for the piers in intimate contact with undisturbed soil. Fill any voids or enlargements in the drilled pier shaft excavations with concrete at the time of drilled pier concrete placement. We recommend using a concrete mix design with a slump of 7 to 9 inches for tremie placement to reduce the potential for concrete arching and provide a workable material. We recommend using temporary form, such as Sonotube, to form the top portion of the drilled piers. The use of these top forms is a very beneficial aid to current placement and orientation of the anchor bolts. Concrete Abutments Caving and sloughing of the native and fill granular soils should be anticipated during excavation for bridge abutments. The contractor should be prepared to over excavate and form the abutments. The sides of the foundations should be constructed straight and vertical to reduce the risk of frozen soil adhering to the concrete and raising the foundation. Groundwater may be encountered at the base of the north abutment excavation while we anticipate the southern excavation to be dry. We anticipate groundwater accumulation may be controlled by properly constructed sumps and pumps installed and pumped dry prior to excavating the proposed abutment. The sumps should remain in use during the remainder of excavation operations. All excavations should be safely sheeted, shored, sloped, or braced in accordance with MI-OSHA requirements. If material is stored or equipment is operated near an excavation, stronger shoring must be used to resist the extra pressure due to the superimposed loads. Care should always be exercised when excavating near existing roadways or utilities to avoid undermining. GENERAL COMMENTS We have formulated the evaluations and recommendations presented in this report relative to site preparation and foundations on the basis of data provided to us relating to the location, type, and grade for the proposed site. Any significant change in this data should be brought to our attention for review and evaluation with respect to the prevailing subsurface conditions. Furthermore, if changes occur in the design, location, or concept of the project, the conclusions and recommendations contained in this report

9 September 2, 2015 Page 7 are not valid unless G2 Consulting Group, LLC reviews the changes. G2 Consulting Group, LLC will then confirm the recommendations presented herein or make changes in writing. The scope of the present investigation was limited to evaluation of subsurface conditions for the support of proposed bridge structure and other related aspects of the development. No chemical, environmental or hydrogeological testing or analyses were included in the scope of this investigation. We base the analyses and recommendations submitted in this report upon the data from the soil borings performed at the approximate locations shown on the Soil Boring Location Plan, Plate No. 1. This report does not reflect variations that may occur away from the actual boring locations. The nature and extent of any such variations may not become clear until the time of construction. If significant variations then become evident, it may be necessary for us to re-evaluate our report recommendations. Accordingly, we recommend G2 Consulting Group, LLC observe all geotechnical related work, including foundation construction, subgrade preparation, and engineered fill placement. G2 Consulting Group, LLC will perform the appropriate testing to confirm the geotechnical conditions given in the report are found during construction.

10 APPENDIX Soil Boring Location Plan Plate No. 1 Soil Boring Logs Figure Nos. 1 and 2 Unconfined Compressive Strength Test Figure No. General Notes Terminology Figure No.

11 Soil Borings Drilled by Strata Drilling, Inc. on September 8, 2015 Fieldcrest Pedestrian Bridge Fieldcrest Road Green Oak Township, Michigan Project No Drawn By: ALS Date: 9/21/15 Scale: NTS Plate No. 1

12 Project Name: Fieldcrest Pedestrian Bridge Soil Boring No. B-1 Project Location: Fieldcrest Road Green Oak Township, Michigan Latitude: Longitude: SUBSURFACE PROFILE SOIL SAMPLE DATA ELEV. ( ft) 8.0 PRO- FILE GROUND SURFACE ELEVATION: 88.0 ft ± Fill: Brown Sand Topsoil: Dark Brown Silty Sand Fill: Medium Compact Brown Gravelly Sand with trace silt and concrete pieces Medium Compact Brown Silty Sand with trace gravel DEPTH ( ft) 5 SAMPLE TYPE-NO. S-1 S-2 BLOWS/ -INCHES STD. PEN. RESISTANCE (N) 1 28 MOISTURE CONTENT (%) DRY DENSITY (PCF) UNCONF. COMP. STR. (PSF) Medium Compact Brown Sand with trace silt and gravel Medium Gray Silty Clay with trace sand and gravel S- S Loose Brown Silty Sand with trace gravel 15 S Medium Compact Brown Silty Sand with trace gravel S SOIL / PAVEMENT BORING GPJ G2 CONSULTING DATA TEMPLATE.GDT 9/2/ Total Depth: Drilling Date: Inspector: Contractor: Driller: Medium Compact Gray Silty Sand with trace gravel Medium Compact Gray Silty Sand with trace gravel, occasional medium clayey silt layers End of 0 ft 0 ft September 8, 2015 Strata Drilling, Inc. B. Sienkiewicz Drilling Method: 2-1/ inch inside diameter hollow stem augers S-7 S Water Level Observation: 12 feet during drilling; wet cave at 10 feet following auger refusal 1 1 Notes: * Calibrated Hand Penetrometer Excavation Backfilling Procedure: Borehole backfilled with auger cuttings Figure No. 1

13 Project Name: Fieldcrest Pedestrian Bridge Soil Boring No. B-2 Project Location: Fieldcrest Road Green Oak Township, Michigan Latitude: N/A Longitude: N/A SUBSURFACE PROFILE SOIL SAMPLE DATA ELEV. ( ft) 82.0 PRO- FILE GROUND SURFACE ELEVATION: 87.0 ft ± Fill: Brown Sand Fill: Loose Brown Silty Sand with trace gravel 0. DEPTH ( ft) 5 SAMPLE TYPE-NO. S-1 S-2 BLOWS/ -INCHES 5 STD. PEN. RESISTANCE (N) 9 8 MOISTURE CONTENT (%) DRY DENSITY (PCF) UNCONF. COMP. STR. (PSF) Fill: Medium Compact Brown Gravelly Sand with trace silt Fill: Medium Compact Grayish Brown Silty Sand with little gravel and trace organic matter S- S Very Loose Dark Gray Silty Sand with trace gravel and organic matter (Organic Content = 1.1%) 15 S Loose Brown Sand with trace silt and gravel 20 S SOIL / PAVEMENT BORING GPJ G2 CONSULTING DATA TEMPLATE.GDT 9/2/ Total Depth: Drilling Date: Inspector: Contractor: Driller: Medium Gray Clayey Silt with trace sand Medium Compact Gray Silty Sand with trace gravel End of 0 ft 0 ft September 8, 2015 Strata Drilling, Inc. B. Sienkiewicz Drilling Method: 2-1/ inch inside diameter hollow stem augers S-7 S * Water Level Observation: -1/2 feet during drilling; wet cave at 7-1/2 feet following auger refusal Notes: * Calibrated Hand Penetrometer Excavation Backfilling Procedure: Borehole backfilled with auger cuttings Figure No. 2

14 1,800 1,00 1,00 1,200 STRESS, psf 1, US_UNCONFINED GPJ G2 CONSULTING DATA TEMPLATE.GDT 9/2/ Specimen STRAIN, % B-1 S- Gray Silty Clay Classification MC% UC UNCONFINED COMPRESSIVE STRENGTH TEST Project Name: Project Location: G2 Project No.: Fieldcrest Pedestrian Bridge Fieldcrest Road Green Oak Township, Michigan Figure No.

15 GENERAL NOTES TERMINOLOGY Unless otherwise noted, all terms herein refer to the Standard Definitions presented in ASTM 5. PARTICLE SIZE Boulders - greater than 12 inches Cobbles - inches to 12 inches Gravel - Coarse - / inches to inches - Fine - No. to / inches Sand - Coarse - No. 10 to No. - Medium - No. 0 to No Fine - No. 200 to No. 0 Silt mm to 0.07mm Clay - Less than 0.005mm CLASSIFICATION The major soil constituent is the principal noun, i.e. clay, silt, sand, gravel. The second major soil constituent and other minor constituents are reported as follows: Second Major Constituent (percent by weight) Minor Constituent (percent by weight) Trace - 1 to 12% Trace - 1 to 12% Adjective - 12 to 5% Little - 12 to 2% And - over 5% Some - 2 to % COHESIVE SOILS If clay content is sufficient so that clay dominates soil properties, clay becomes the principal noun with the other major soil constituent as modifier, i.e. sandy clay. Other minor soil constituents may be included in accordance with the classification breakdown for cohesionless soils, i.e. silty clay, trace sand, little gravel. Consistency Unconfined Compressive Strength (psf) Approximate Range of (N) Very Soft Below Soft 500-1,000 - Medium 1,000-2, Stiff 2,000 -, Very Stiff,000-8, Hard 8,000-1, Very Hard Over 1,000 Over 50 Consistency of cohesive soils is based upon an evaluation of the observed resistance to deformation under load and not upon the Standard Penetration Resistance (N). COHESIONLESS SOILS Density Classification Relative Density % Approximate Range of (N) Very Loose Loose Medium Compact Compact Very Compact Over 50 Relative Density of cohesionless soils is based upon the evaluation of the Standard Penetration Resistance (N), modified as required for depth effects, sampling effects, etc. SAMPLE DESIGNATIONS AS - Auger Sample Cuttings directly from auger flight BS - Bottle or Bag Samples S - Split Spoon Sample - ASTM D 158 LS - Liner Sample with liner insert inches in length ST - Shelby Tube sample - inch diameter unless otherwise noted PS - Piston Sample - inch diameter unless otherwise noted RC - Rock Core - NX core unless otherwise noted STANDARD PENETRATION TEST (ASTM D 158) - A 2.0 inch outside-diameter, 1-/8 inch inside-diameter split barrel sampler is driven into undisturbed soil by means of a 10-pound weight falling freely through a vertical distance of 0 inches. The sampler is normally driven three successive -inch increments. The total number of blows required for the final 12 inches of penetration is the Standard Penetration Resistance (N). Figure No.