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HomeMy WebLinkAbout20070474.tiff resaN v SOILOGIC September 23, 2005 Mr. Jason Slater 8567 Weld County Road 86 Fort Collins, Colorado 80524 Re: Geotechnical Subsurface Exploration Proposed Slater Residence (8567 Weld County Road 86) Weld County, Colorado Soilogic Project # 05-1023 Mr. Slater: Soilogic, Inc. (Soilogic) personnel have completed the geotechnical subsurface exploration you requested for your proposed residence to be constructed at 8567 County Road 86 in Weld County, Colorado. The results of our subsurface exploration are included with this report. We understand the proposed residence will be a one or two-story wood frame structure constructed over a walkout basement. A detached garage is also anticipated adjacent to the west side of the proposed residence. Foundation loads for the structure are expected to be light with continuous wall loads less than 2.5 kips per lineal foot and individual column loads less than 35 kips. Small grade changes are expected to develop finish site grades in the residence area. The purpose of our investigation was to describe the subsurface conditions encountered in the completed site borings and develop the test data necessary to provide recommendations concerning design and construction of the residence foundations and support of floor slabs and exterior flatwork. The conclusions and recommendations outlined in this report are based on the results of the completed field and laboratory testing and our experience with subsurface conditions in this area. Soilogic, Inc. 2007-0474 1435 Hilltop Circle • Windsor, CO 80550 • (970)674-3430 Slater Residence Soilogic#05-1023 2 r SITE DESCRIPTION The proposed residence will be constructed at 8567 Weld County Road 86 west of Black Hollow Reservoir in Weld County, Colorado. The existing lot encompasses approximately 30 acres and is the site of an existing residence located toward the front of the lot adjacent to Weld County Road 86. The location of the proposed residence is situated toward the back of the lot on a site ridge. At the time of our site exploration, the area of the proposed residence was vegetated and sloping to the south. The maximum difference in ground surface elevation across the residence footprint was estimated to be approximately 5 to 7 feet at that time. EXPLORATION AND TESTING PROCEDURES To develop subsurface information in the area of the proposed residence, two (2) soil borings were extended to depths ranging from approximately 15 to 30 feet below present site grades within the approximate building footprint. The boring locations were established in the field by Mr. and Mrs. Slater and Soilogic personnel by estimating angles and distances from identifiable site references. A diagram indicating the approximate boring locations is included with this report. A graphic log of each of the auger borings is also included. The test holes were advanced using 4-inch diameter continuous flight auger powered by a truck-mounted CME-45 drill rig. Samples of the subsurface materials were obtained at frequent intervals using California barrel and split-barrel sampling procedures in general accordance with ASTM specification D-1586. Penetration resistance measurements were obtained by driving the standard sampling barrels into the substrata using a 140 pound hammer falling a distance of 30 inches. The number of blows required to advance the samplers a distance of 12 inches is recorded and helpful in estimating the consistency, relative density or hardness of the soils or bedrock encountered. In the California barrel sampling procedure, relatively undisturbed samples are obtained in removable brass sleeves. Samples of the subsurface materials obtained in the field were sealed and returned to the laboratory for further evaluation. Slater Residence Soilogic#05-1023 3 The samples collected were tested in the laboratory to measure natural moisture content and visually classified in accordance with the Unified Soil Classification System (USCS). The USCS group symbols are indicated on the attached boring logs. An outline of the USCS classification system is included with this report. Classification of bedrock was completed by visual observation of disturbed samples. Other bedrock types could be revealed through Petrographic analysis. As part of the laboratory testing, a calibrated hand penetrometer (CHP) was used to estimate the unconfined compressive strength of essentially cohesive specimens. The CHP also provides a more consistent estimate of soil consistency than tactual observation alone. Dry density, Atterberg limits, -200 wash and swell/consolidation tests were completed on selected samples to help better define specific sample characteristics. Atterberg limits tests are used to determine soil plasticity. Minus -200 wash tests are used to determine the percentage of fine grained soils (clay and silt) in a sample. Swell/consolidation tests are performed to evaluate soil volume change potential with variation in moisture content. The results of the completed laboratory tests are outlined on the attached boring logs and swell/consolidation summary sheet. SUBSURFACE CONDITIONS The materials encountered in the completed site borings can be summarized as follows. Approximately 2 to 4 inches of topsoil and vegetation was encountered at the surface at the boring locations. The topsoil/vegetation was underlain by brown, medium stiff to stiff, sandy lean clay. The lean clay extended to a depth of approximately 2 feet below ground surface and was underlain by weathered claystone bedrock. The claystone was colored brown/grey/rust, was moderately hard and showed moderate to high swell potential at in-situ moisture and density conditions. The site borings were terminated at depths ranging from approximately 15 to 30 feet below ground surface in the weathered bedrock. The stratigraphy indicated on the included boring logs represents the approximate location of changes in soil and rock types. Actual changes may be more gradual than those indicated. Slater Residence Soilogic#05-1023 4 Groundwater was not encountered in the completed site borings at the time of drilling Groundwater levels will vary seasonally and over time based on weather conditions, site development, irrigation practices and other hydrologic conditions. Perched groundwater conditions may also be encountered at times throughout the year. Perched water is commonly encountered in soils overlying less permeable bedrock. The location and amount of perched water can also vary over time. ANALYSIS AND RECOMMENDATIONS General The claystone bedrock encountered at this site exhibited high plasticity and moderate to high swell potential at current moisture and density conditions. Heaving of site improvements placed directly on or immediately above the expansive bedrock would be expected as the moisture content of the subgrade soils increases subsequent to construction. In order to reduce the potential for movement of the proposed structures in ,r-• the expansive soils environment, we recommend the residence and detached garage be supported on a drilled pier foundation system. Drilled piers would anchor the residence and detached garage into bedrock significantly reducing the potential for total and differential movement of the structures. There will remain some risk associated with building in areas of expansive soils. The risk of some movement and associated distress cannot be eliminated. Drilled Pier Foundations We recommend drilled pier foundations extend a minimum of 12 feet into competent bedrock with a minimum shaft length of 20 feet and be designed using a maximum end bearing pressure of 25 kips per square foot (ksf). The piers should be designed to maintain a minimum dead load pressure of 7 ksf based on the cross-sectional area of the piers. An increase in pier capacity can be developed through credit from skin friction by increasing the minimum length and bedrock penetration requirements outlined above. -. An allowable skin friction of 2,500 psf could be used for that portion of the pier shaft Slater Residence Soilogic#05-1023 5 extended below the recommended minimum depths. If the minimum required dead load pressure cannot be achieved, an uplift skin friction resistance value of 1,700 psf could be used to calculate additional uplift resistance for the increase in pier length only. Piers should be designed with full length steel reinforcement to help transmit any axial tension loads that may develop in the pier shaft. A minimum 6-inch continuous void space should be constructed beneath the grade beams to concentrate dead load on the piers and allow for some movement of the subgrade soils without transmitting stresses to the overlying structure. Voids should be formed using approved methods to prevent soil and debris from entering the void space. Void form material should be collapsible enough such that expansive soil uplift forces cannot be transmitted through the void form to mobilize the grade beams. Based on the materials encountered in the completed site borings, we expect the pier excavations could be completed using conventional augering techniques. Areas of well cemented or very hard bedrock could be encountered requiring specialized rock bit and/or coring equipment. Pier excavations would be expected to remain stable for short periods during construction such that we do not expect temporary casing of the drilled shafts would be required. If groundwater is encountered during drilling, casing of the holes and pump or tremmie pipe concrete placement methods may be required. Pier concrete should have a slump in the range of 5 to 8 inches and be placed in the pier holes immediately after the completion of drilling, cleaning and placement of the reinforcing steel. Care should be taken in forming the upper edges of the pier excavation to avoid "mushrooming" at the top of the drilled pier excavations. The mushroom shape will provide additional area for expansive soil uplift forces. Cylindrical cardboard forms or other approved means may be necessary to maintain a consistent upper shaft diameter. We estimate long term settlement of the drilled caisson foundations designed and constructed as outlined above resulting from the assumed structural loads would be less than % of an inch. Additional movement could occur if water from any source is allowed to infiltrate the foundation soils. Interior Floors Slater Residence Soilogic#05-1023 6 In order to reduce the potential for movement of the residence floor slabs, we recommend all interior living area floor slabs be constructed as structurally supported floors over a void space. A minimum 8-inch void space should be developed beneath the bottom of the floor system. A larger crawl space area has the advantage of allowing maintenance of grade beam void spaces and sub floor utilities. We recommend the subgrades in the void space area be sloped to drain to a perimeter drain system in case of water infiltration. In addition, care should be taken to reduce the potential for development of moist air conditions in the voided area. Garage Floor To reduce the potential for movement of the garage floor slab subsequent to construction, we recommend a zone of reconditioned soil be developed beneath the garage floor slab. The reconditioned mat will provide a zone of material immediately beneath the garage floor slab which will have low potential for volume change subsequent to construction. r-- The low volume change mat and surcharge loads placed on the underlying soils by the reconditioned mat would reduce the potential for total and differential movement of the supported slab. The reconditioned zone would also assist in distributing movement in the event that some swelling of the materials underlying the reconditioned zone occurs. The overexcavation zone should extend at least 3 feet below top of floor slab subgrade level. Overexcavation backfill soils should consist of low volume change and relatively impermeable soils free from organic matter, debris and other objectionable materials. The near surface site lean clay could be used as overexcavation backfill beneath the garage floor slab. Claystone bedrock should not be used as overexcavation backfill or fill in any structural areas of the site. Import soils should have a minimum of 20% fines (material passing the #200 size sieve) in order to reduce the potential of those materials to pond and transmit water. After stripping and completing the overexcavation, the essentially cohesive backfill soils should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted to be within the range of 94 to 98% of the materials standard Proctor maximum dry density. The moisture content of the backfill soils should be adjusted to be within the range of-1 to +3% of standard Proctor optimum moisture content at the time of compaction. When adjusted to the high end of Slater Residence Soilogic#05-1023 7 the recommended moisture range, some "pumping" of the subgrade soils may occur and would be expected. Care should be taken to maintain the proper moisture content of the subgrade soils prior to concrete placement. The prepared structural mat should not be left exposed for extended periods of time. In the event that the reconditioned soils are allowed to dry out or if rain, snowmelt or other water sources are allowed to infiltrate into the reconditioned area, reworking of the subgrade soils or removal/replacement procedures may be required. Inherent risks exist when building in areas of expansive soils. The overexcavation/backfill procedures outlined above will reduce but not eliminate the potential for movement of the garage floor slab. The in-place materials below the moisture conditioned zone can experience volume change with increases in moisture content and create some slab movement. With the expansive nature of the site soils, some movement of the garage floor slab should be expected. Exterior Flatwork Exterior flatwork may be supported on existing site soils or newly placed and compacted fill. All existing topsoil and vegetation should be removed from exterior flatwork areas. After stripping and completing all cuts and prior to placement of any fill or flatwork, we recommend the in-place soils be scarified to a minimum depth of 9 inches, adjusted in moisture content and compacted to be within the range of 94 to 98% of the material's standard Proctor maximum dry density. The moisture content of the scarified soils should be adjusted to be within the range of -1 to +3% of standard Proctor optimum moisture content at the time of compaction. Fill soils required to develop exterior flatwork subgrades should consist of approved low volume change soils free from organic matter, debris or other objectionable materials. Soils similar to those used as overexcavation backfill could be used as fill beneath exterior flatwork. The higher plasticity claystone bedrock should not be used as fill beneath exterior flatwork. We recommend suitable fill materials be placed in loose lifts r Slater Residence Soilogic#05-1023 8 not to exceed 9 inches thick, adjusted in moisture content and compacted as recommended for the scarified soils above. Care should be taken to avoid disturbing exterior flatwork subgrades. Subgrade soils expected to receive flatwork concrete should be evaluated closely prior to concrete placement. If areas of disturbed, wet and softened, or dry subgrade soils develop during construction, those materials should be removed and replaced or reworked in place prior to concrete placement. Exterior flatwork concrete will experience some movement after placement as the subgrade soils increase in moisture content. Overexcavation/backfill procedures could be considered to reduce the potential for post-construction movement of exterior slabs-on- grade. Basement Construction We recommend a perimeter drain system be installed around all below grade areas to help alleviate the potential for development of hydrostatic pressures behind the below grade walls and reduce the potential for water infiltration into the basement area. A perimeter drain system should consist of a perforated drain pipe surrounded by a minimum of six (6) inches of free draining gravel. A filter fabric should be considered around the free draining gravel or perforated pipe to reduce the potential for an influx of fine grained soils into the system. The drain pipe should be placed at approximate bottom of void space level around the exterior perimeter of the structure and run to a sump pit or free outfall with a minimum slope of 1/8 inch per foot to facilitate efficient water removal. If a free outfall will be considered, measures to help reduce the potential for reverse flow and animal access into the system should be considered. Backfill placed adjacent to the below grade walls should consist of low volume change potential and relatively impervious soils which are free from organic matter, debris and other objectionable materials. The site claystone bedrock should not be used as backfill adjacent to basement walls. The backfill soils should be placed in loose lifts not to exceed 9 inches thick, adjusted to be within -1 to +3% of standard Proctor optimum moisture content and compacted to at be within the range of 94 to 98% of the materials Slater Residence Soilogic#05-1023 9 standard Proctor maximum dry density. Excessive lateral stress can be imposed on the below grade walls when using heavier mechanical compaction equipment. We recommend compaction of the basement wall backfill soils be completed using light mechanical or hand compaction equipment. Lateral Earth Pressures For design of below grade walls where preventative measures have been taken to reduce the potential for development of hydrostatic loads on the walls, we recommend using an active equivalent fluid pressure of 50 pounds per cubic foot. Some rotation of the basement wall must occur to develop the active earth pressure state. That rotation can result in cracking of the basement walls typically in between corners and other restrained points. Variables that affect lateral earth pressures include but are not limited to the nature of the backfill soil, backfill compaction and geometry, wetting of the backfill soils, surcharge loads and point loads developed in the backfill materials. The recommended equivalent fluid pressures do not include a factor of safety to accommodate for significant changes to the variables outlined above nor an allowance for hydrostatic loads. Excessive compaction of the wall backfill, surcharge loads placed adjacent to the basement walls and use of expansive soil backfill can add to the lateral pressures causing the design values outlined above to be exceeded. Drainage Positive drainage is imperative for long term performance of the proposed residence and associated site improvements. We recommend positive drainage be developed away from the structure with twelve (12) inches of fall in the first 10 feet away from the building during construction and throughout the life of the site improvements. Shallower slopes could be considered in hardscape areas. In the event that some settlement of the backfill soils occurs adjacent to the residence, the original grade outlined above should be immediately restored. Slater Residence Soilogic#05-1023 10 r Care should be taken in the planning of landscaping to avoid features which could result in the fluctuation of the moisture content of the foundation bearing and/or flatwork subgrade soils. We recommend watering systems be placed a minimum of 5 feet away from the perimeter of the site structure and be designed to discharge away from all site improvements. Gutter systems should be considered to help reduce the potential for water ponding adjacent to the structure with the gutter downspouts, roof drains or scuppers extended to discharge a minimum of 5 feet away from structural, flatwork and pavement elements. Water which is allowed to pond adjacent to the site improvements can result in unacceptable performance of those improvements over time. GENERAL COMMENTS This report was prepared based upon the data obtained from the completed site exploration, laboratory testing, engineering analysis and any other information discussed. The completed borings provide an indication of subsurface conditions at the boring locations only. Variations in subsurface conditions can occur in relatively short distanced away from the borings. This report does not reflect any variations which may occur across the site or away from the borings. If variations in the subsurface conditions anticipated become evident, the geotechnical engineer should be notified immediately so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any biological or environmental assessment of the site or identification or prevention of pollutants or hazardous materials or conditions. Other studies should be completed if concerns over the potential of such contamination or pollution exist. The geotechnical engineer should be retained to review the plans and specifications so that comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. The geotechnical engineer should also be retained to provide testing and observation services during �.. construction to help determine that the design requirements are fulfilled. eTh Slater Residence Soilogic#05-1023 I] This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with the generally accepted standard of care for the profession. No warranties express or implied, are made. The conclusions and recommendations contained in this report should not be considered valid in the event that any changes in the nature, design or location of the project as outlined in this report are planned, unless those changes are reviewed and the conclusions of this report modified and verified in writing by the geotechnical engineer. We appreciate the opportunity to be of service to you on this project. If we can be of further service to in any way or if you have any questions concerning the enclosed information, please do not hesitate to contact us. Very Truly Yours, Soilogic, Inc. "P00 REO/ • S'•. i ' 6 6 LL . ' . : J S/ONAL Wolf von Carlowit..P.E. Principal Engineer 7NSEPTEMBER 2005 BORING LOCATION DIAGRAM SO1LOGIC PROJECT # 05-1023 Approximate Detached Garage Location Approximate Residence Location 8-1 8-2 ii NOT TO SCALE Existing Residence Weld County Road 86 SLATER RESIDENCE WELD COUNTY, COLORADO SLATER RESIDENCE LOG OF BORING B-1 WELD COUNTY, COLORADO SDI-LOGIC Project# 05-1023 September 2005 Sheet 1/2 Drilling Rig: CME 45 Water Depth Information Start Date 9/19/2005 Auger Type: 4"CFA During Drilling None Finish Date 9/19/2005 Hammer Type: Automatic After Drilling None Surface Elev. - Field Personnel: WvC 24 Hours After Drilling w w %Passing ai SOIL DESCRIPTION Depth t- "N" MC DD q„ %Swell @ Swell Atterberg Limits #200 Sieve O 0t) rA (%) (pd) (Pan 500 psi Pressure LL PI (%) TOPSOIL AND VEGETATION - CL SANDY LEAN CLAY 1 light brown medium stiff 2 CLAYSTONE 3 brown/grey/rust - moderately hard 4 CS 22 13.0 9000+ 5 SS 50/8 14.5 9000+ 6 7 e �1 9 10 CS 50/2 14.4 113.1 9000+ 6.7% -6000 psf 58 41 99.4% 11 12 13 14 15 SS 50/6 17.0 9000+ 16 17 18 • 19 20 21 22 23 fr\ 24 Continued On Sheet 2 of 2 26 SLATER RESIDENCE LOG OF BORING B-1 WELD COUNTY, COLORADO SOILOGIC Project* 05-1023 September 2005 Sheet 2/2 Drilling Rig: CME 45 Water Depth Information Start Date 9/19/2005 Auger Type: 4"CFA During Drilling None Finish Date 9/19/2005 Hammer Type: Automatic After Drilling None Surface Elev. - Field Personnel: WvC 24 Hours After Drilling ,a ffi %Passing SOIL DESCRIPTION Depth "N" MC DD q„ %Swell @ Swell Atterberg Limits #200 Sieve an tit (%l (Pot) (psq 500 psf Pressure LL PI (xl Continued From Sheet 1 of 2 26 CLAYSTONE Contd.brown/grey/rust 27 moderately hard - 26 29 30 BOTTOM OF BORING 30.0' 31 32 33 34 35 36 37 36 39 40 41 42 43 44 45 46 47 46 49 50 SLATER RESIDENCE LOG OF BORING B-2 WELD COUNTY, COLORADO SOJLOGIC Project# 05.1023 September 2005 Sheet 1/1 Drilling Rig: CME 45 Water Depth Information Start Date 9/19/2005 Auger Type: 4"CFA During Drilling None Finish Date 9/19/2005 Hammer Type: Automatic After Drilling None Surface Elev. - Field Personnel: WvC 24 Hours After Drilling to w %Passing SOIL DESCRIPTION Depth ci "N" MC DD q„ %Swell @ Swell Atterberg Limits _ #200 Sieve InlLic 1%) (PO (Ps?I 500 psf Pressure LL PI (%l TOPSOIL AND VEGETATION - CL SANDY LEAN CLAY 1 light brown • medium stiff 2 CLAYSTONE 3 SS 18 13.1 9000+ brown/grey/rust - moderately herd 4 5 CS 43 18.4 9000+ 6 a 9 10 SS 24 17.1 9000+ 11 12 13 14 15 SS 50 16.6 9000+ BOTTOM OF BORING 155' 16 17 18 19 20 21 22 23 24 25 . ^ SLATER RESIDENCE `.--‘ WELD COUNTY, COLORADO Project# 05-1023 r^, September 2005 SWELL/CONSOLIDATION TEST SUMMARY 12 10 - _.. _ _..-.`-- --L, e _ .. r m CO i I o y t 1 ware.sdad I .4 1 r I s -6 ea O x e I -10 -- '- -1 1----�; H - i_� -12 10 100 1000 10000 100000 Load Applied (psf) IP 1 Sample ID: B-1, S-3 @ 9' Sample Description: Brown/Grey/Rust Claystone Initial Moisture 15.1% Liquid Limit 58 Final Moisture 21.0% Plasticit Index 41% Swell @ 500 psf 5.7% % Passing#200 99.4% Swell Pressure —6000 psf Dry Density 113 1 pcf r" SO jLOcic / ' a UNIFIED SOIL CLASSIFICATION SYSTEM 4.-,,, (USCS) Coarse-Grainer) Grovels more Ihon Clean Gravels Less CW Well-graded grave Soils more than 50% of course man 5% lines Cu>s nod <Cc≤Jr 50% r 0 rood on on No. ,clam et, 0P Poorly-graded grove/ Na. 4 siea Cu<4 a+d/er Na. 4U0 sieve m ------------ rinc! Classify us ML or MH GM Silly gravel, OH more than 135 GC Clayey Cr avel"" lines lino classify as Cl. or Ciii— --- C >6 and 1<[c5.r Sw Well-gr�—ded send' Sands 50% o Clean Sands Less u __ — --- oire coorse than 57. fines 5P Poo ly-grudcU sand' Ire,,lion posses Cu<5 and/or I>Cc>No 4 sieve Sands will linen lines classify — os ML or MH _ SM Silly sand more than 12% lines r'ncs Ctassi ly os CL or CH SC Clayey sand"' fine-Grained Silts end Cloys ,nor game PIN and plots on or above 'Aline Cl. Lean cloy"'_� Soils 515% or Liauid Llmii lose PI<4 or plots below 'A'Llrm' ML Silt.'r__ ore passes the Il+gn 50 No. 200 sieve eil - n dried Orqu_¢ Clny".n ----- organic Liquid Ln <0.J5 OL ----- Liquid Limit not dried Organic sill•`e'e Ua --- _ Sins and Cloys in or genic PI pints on or above -A'Llne CH Pal cloy•L' _ _—___ _—Licliliinorc Limit 50 or PI plots below "A'Linu l.114Elastic Sill"�_- rOrC --��- --- Liquid I - oven dried Co g__nir cloy` argamc -- <0.>5 OH Liquid Lund - not dried __ Organic sill_"_--I y organic moiler, dark in color. and organ C odor P F PerilJ Highly rgpme salts -- Primarily h1 a is la leegb , ?Oa.. nua 'Band a mo+rnn' pusolno s l-'n. l'J +Cu-U•./U�Ce �D nlep� ant Or •'In Win el . Nm"eld tour•' but •s' ' aoa~aonlmna a la ule en.. eo0 un + ,scd.,n.no0uv sand.add n I'°'0 ln. eaa"n. cone e+ n,env d.,a. w u „ .. xna nerd. ado-.l r, ,nna to ,e.ElThm drem n Hs class urv,ed caul `,p nlilo eel cunning x loo pm Moo yIYJ p 000501. am w Ill Any.soli ono as CL-ul. use duo aymm� o.dnlr Ndnlls a=... ell'RI only. "a+'^ A ,aurae_ GC- u�al 5C�5M. ome / a Cy all a.em arp.al n meenrt. onti.ah 0,9005 lets Iv 'HIS end plain . °1n. Cw-Gc -moans trowel :ryC ay CP- paody-Tenm 74741 ml" gr1 solre i nLsagro.n ode,d arose" 1 cob o on os,eere-ca apnea-aaneg <nes . o soli p rlo - P1 viols on as .9. one. A ' a NnOola:' ! In ^e reed a dean 'rl Al`o`ng+eau pouf• thuds.] area. so, n 5 -SM .ll-grnded tone Cl.- clay 51Y-SC .et-grnded , pill, fitly N-5M poorly aoerdua e wills sill 5P-5C spun,aueud stun +Ih ti00 ar•,.a n•-sal a � y, n.,v,.up iu.al C e la r Mhl rel OH o---.o.J rp----,o - lb Alb Lam In(LLI�-- su rp a I Fitly Grained Soils Coarse Grained Soils Bedrock Consistency Blows/ft Relative Density Blows/f t Weathering Q0ff Very Loose 0-50 Weathered .500 Very Soft 5-8-q Competent Soft Loose 50• 0 -1000 Degree of Weathering 1001-2000 Medium 9-12 MSlediulym Dense B 00/4000 Stiff 13.30 Medium Dense Slight: Slight decomposition,possible color change 4001-8000 Very Stiff 31-50 Dense Moderate: Some decomposition and color change throughout �w50• Very Dense High: Rock highly decomposed,may be extremely broken 800/16000 Very Hard Hello