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Geotechnical Evaluation ReportA Preliminary Geotechnical Evaluation Report Proposed Boulder Cove Residential Development 62nd Street & Strawberry lane Chanhassen, Minnesota Prepared for Cottage Homesteads at Boulder Cove, LLC Professional Certification I hereby certify that this plan, specification or report was prepared by me or under my direct supervision and that I am a duly Licensed Professional Engineer under the laws of the State of Minnesota. 011 q l ►I /li ... ��. �roj n "iiiIe�� e 3,icen4 412G a�Rjiary 20,2006. I'' � ►111111 ►� ,`` Project BL -05 -06006 Braun Intertec Corporation BRAUN Braun Intertec Carporaflon I Phone: 952 995 2000 1 1001 Hampshire Avenue S Fax: 952 - 995.2020 INTERTEC Minneapolis, MN 55438 Web: brounintertec.com January 20, 2006 Mr. Roger Derrick Cottage Homesteads at Boulder Cove, LLC 7300 Metro Blvd. Suite 360 Edina, MN 55439 Re: Preliminary Geotechnical Evaluation Proposed Boulder Cove Residential Development Church Road and Strawberry Lane Chanhassen, Minnesota Dear Mr. Derrick: Project BL -05 -06006 We have completed the preliminary geotechnical evaluation for the proposed residential development in Chanhassen, Minnesota. The purpose of the geotechnical evaluation was to assist you and your consultants in evaluating the soil and groundwater conditions for design of the proposed development. The evaluation was completed in general accordance with our Proposal for Geotechnical Evaluation, dated December 13, 2005. Please refer to the attached report for a detailed summary of our analyses and recommendations. Additional attention should be paid to Section A.5, which discusses the site conditions and Sections C.2 and C.3, which outline removal of unsuitable soils and excavation depths. If we can provide additional assistance or observation and testing services during construction, please contact Marty Gray 952.995.2254 or James Craig at 952.995.2372. Sincerely, BRAUN INTERTEC CORPORATION -A y - -- Ma A. Gra Marty Y, Project Engineer mes J. Craig Jr., PE Senior Engineer Attachment: Geotechnical Evaluation Report c: Cara Schwahn -Otto; Otto Associates, Inc. Georpt- Cottage Homesteads Providing engineering and environmental solutions since 1957 Table of Contents Description Page A. Introduction ......................................................................................... ............................... 1 A.1. Project ...................................................................................... ..............................1 _. A.2. Purpose ................................................................................... ............................... 1 A.3. Scope ...................................................................................... ............................... 1 A.4. Documents Provided ............................................................... ............................... 1 A.5. Site Conditions ....................................................................... ............................... 2 _ A.6. Locations and Elevations ........................................................ ............................... 2 B. Results ................................................................................................. ............................... 2 B.1. Soil Boring Logs ..................... ................................................ ............................... B.2. Soils ........................................................................................ ............................... 3 B.3. Groundwater ............................................................................ ..............................3 B.4. Laboratory Tests ..................................................................... ............................... 3 C. Preliminary Analyses and Recommendations ..................................... ............................... 3 C.1. Construction ........................................................................... ............................... 3 C.2. Discussion of Construction Recommendations, Procedures and Difficulties....... 4 C.2.a. Excavation ................................................................. ............................... C.2.b. Utility Design ............................................................ ............................... 4 C.2.c. Groundwater Control ................................................. ............................... 4 — C.3. ....................... ............................... Building Pad Preparation ...................... ........... 5 C.3.a. Excavation ................................................................. ............................... 5 C.3.b. Fill and Backfill ......................................................... ............................... 5 — CA. ............................ ............................... Foundation Design .... ............................... ... 6 CA.a. Bearing Capacity ....................................................... ............................... 6 CA.b. Footing Depths .......................................................... ............................... 6 _., CA.c. Settlement ................................................................... ..............................6 C.5. Floor Slabs .............................................................................. ............................... 7 C.5.a. Subgrade .................................................................... ............................... 7 ., C.5.b. Vapor Barrier ............................................................. ............................... 7 C.6. Below Grade Walls ................................................................. ............................... 7 C.6.a. Seepage Control ......................................................... ............................... 7 C.6.b. Lateral Earth Pressure ............................................... ............................... 8 — C.7. Retaining Walls ...................................................................... ............................... 9 C.7.a. Excavation ................................................................. ............................... 9 C.7.b. Foundations ............................................................... ............................... 9 C.7.c. Backfill ....................................................................... ..............................9 C.7.d. Lateral Pressures ...................................................... ............................... 10 C.8. Pavement Areas .................................................................... ............................... 10 C.8.a. Subgrade Preparation ............................................... ............................... C.8.b. Proofroll ..................................................................... .............................10 C.8.c. Recommended Assumed R- Value ........................... ............................... 11 C.8.d. Design Sections .......................... ............................. ............................... 11 C.8.e. Recommended Materials ......................................... ............................... 11 C.9. Utilities ................................................................................. ............................... 11 — C.9.a. Excavation ........ .............................11 .......................... ............................... C.9.b. Backfill ...................................................................... .............................12 C.10. Additional Investigation and Testing During Construction . ............................... 12 — C.11. Cold Weather Construction .................................................. ............................... 13 Table of Contents (Continued) Description Page D. Procedures ......................................................................................... ............................... 13 D.1. Drilling and Sampling .......................................................... ............................... 13 D.2. Soil Classification ................................................................. ............................... 13 D.3. Groundwater Observations ................................................... ............................... 13 E. General Conditions ............................................................................ ............................... 14 E.1. Basis of Recommendations .................................................. ............................... 14 E.2. Review of Design ................................................................. ............................... 14 E.3. Groundwater Fluctuations E.4. Use of Report ........................................................................ ............................... 15 E.5. Level of Care ........................................................................ ............................... 15 Appendices Boring Location Sketch _ Log of Boring Sheets ST -1 to ST -8 Descriptive Terminology A. Introduction A.1. Project Cottage Homesteads at Boulder Cove, LLC is proposing to develop the property in Chanhassen, Minnesota for residential purposes. The property is located south of 62nd Street, east of Church Road and north of Hwy 7. The proposed development will likely consist of multi- family homes along with associated roadways and utilities. .-. As part of the proposed project, Cottage Homesteads at Boulder Cove, LLC has contracted Braun Intertec to perform soil borings and a geotechnical evaluation for the proposed residential development. A.2. Purpose The purpose of the preliminary geotechnical evaluation is to assist Cottage Homesteads at Boulder Cove, LLC, and their design team, in evaluating the subsurface soil and groundwater conditions with regard to site grading and construction of residential buildings. ., A.3. Scope The following scope of geotechnical services was established in our Proposal for Geotechnical Evaluation, dated December 13, 2005. • Staking the boring locations and coordinating the locating of underground utilities near the boring locations • Conducting penetration test borings to a nominal depth of 15 to 20 feet below grade • Returning the samples to our laboratory for visual classification and logging by a geotechnical engineer _ • Conducting limited laboratory tests on selected soil samples • Submitting a geotechnical evaluation report containing logs of the borings, our analysis of the field and laboratory tests, and recommendations for site grading, compaction specifications, '— allowable soil- bearing capacity for foundation design and pavement design parameters A.4. Documents Provided Otto Associates, Inc. provided us with Certificate of Survey & Topographic Survey, dated June 16, 2005, last revised September 6, 2005, of the property showing the boundaries and topography for the property and a Concept Plan, dated November 22, 2005. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 2 A.S. Site Conditions The proposed project site is an irregular- shaped parcel of land located south of 62"d Street and Shorewood Oaks residential development, east of Church Road and Church Road 2"d addition residential development and north of Hwy 7 and west of the single family residences at 3530 Hwy 7. The site is gently rolling from high in the east central part of the site to a pond in the southwest part and of the site. There are miscellaneous small hills and berms located in the west and northwest part of the property. On the west portion of the site was a concrete bunker for various types of materials for the landscaping business located on this part of the site. There are open locations mixed with trees surrounding the area used for the landscaping business. A.6. Locations and Elevations For the project, we completed 8 soil borings across the site, denoted as ST -1 to ST -8. The boring locations were selected and staked by Braun Intertec. The boring locations and elevations were measured by Otto Associates, Inc. and should be considered relatively accurate. The attached Soil Boring Location Sketch shows the approximate boring locations. B. Results B.1. Soil Boring Logs Log of Boring sheets indicating the depths and identifications of the various soil strata, penetration resistances, laboratory test results and groundwater observations are attached. The strata changes were inferred from the changes in the penetration test samples and auger cuttings. The depths shown as changes between the strata are only approximate. The changes are likely transitions and the depths of the changes vary between the borings. Geologic origins presented for each stratum on the Log of Boring sheets are based on the soil types, blows per foot, and available common knowledge of the depositional history of the site. Because of the complex glacial and post - glacial depositional environments, geologic origins can be difficult to ascertain. A detailed investigation of the geologic history of the site was not performed. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 3 B.2. Soils The soils encountered by the soil borings generally consisted of 1/2 to 3 1/2 feet of organic, clayey topsoil at the surface. Below the topsoil, the borings generally encountered a mixture of fat clay, lean clay, sandy lean clay, clayey sand and silty sand to the boring termination depths. The penetration resistances in the clayey soils ranged from 3 to 26 blows per foot (BPF), indicating consistencies of rather soft to very stiff. _. The penetration resistances in the sandy soils ranged from 7 to 14 BPF, indicating consistencies of loose to medium dense. B.3. Groundwater Groundwater was observed at all of the boring locations during or immediately after drilling operations at a range of 3 to 16 feet below the existing elevation, which corresponds with an elevation of 969 1/2 to 962 feet. The water encountered during the drilling was likely perched in the sand seams or the outwash soil layers. Due to the low permeability of the soils, it may take several days or weeks for a groundwater level to stabilize in an open borehole. Annual and seasonal variations in water levels should also be anticipated. B.4. Laboratory Tests Laboratory tests were completed on selected soil samples in accordance with ASTM procedures. The test results can be found on the Log of Boring sheets opposite the soil sample tested. The laboratory tests performed during this evaluation included pocket penetrometer, moisture content, moisture density test, Atterberg Limits and percent passing the number 200 sieve. C. Preliminary Analyses and Recommendations C.1. Construction We understand the proposed construction will likely include wood - framed multi - family structures with associated streets and underground utilities. The structures could have shallow to full -depth basements or could be slab -on -grade structures. We anticipate wall and column loads will be relatively light. For this report, we have assumed that wall loads will be less than 3 kips (3,000 pounds) per linear foot and columns loads, if any, will be less than 75 kips. We anticipate associated paved road and underground utilities will also be constructed as part of the project. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 4 It will be very important for us to review design plans as they are developed. Depending on the proposed final grade and structure type (slab -on -grade or full basement), the amount of corrective earthwork will vary. C.2. Discussion of Construction Recommendations, Procedures and Difficulties C.2.a. Excavation Based on the soil boring results, it is our opinion the proposed residential structures can be supported on spread- footing foundations bearing on medium consistency natural soils or properly compacted structural fill. However, some areas of the site will also require excavation of unsuitable soils prior to construction. Typical excavation depths at the boring locations to remove the topsoil or fill should range from approximately 1/2 to 4 feet below existing grade. Some of the soils in the soil borings were classified as fat clay. These soils generally appear suitable for building support. However, these soils should not directly support building foundations. At least 3 feet of lean clay should be used to cap the fat clay, separating the fat clay from the bottom of footings. The purpose of this lean clay cap is to minimize moisture variation in the fat clay. The fat clay has some potential to swell or shrink with moisture changes. Also, the 3 feet of compacted fill will reduce the footing stress on the fat clay. Extensive laboratory tests on the fat clay were not part of this scope of evaluation. Some of the softer zones may be subject to consolidation due to moderate foundation loads. We recommend settlement estimates be made based on proposed structure on final grade design. Additional borings and laboratory tests may be needed to complete the analysis. C.2.b. Utility Design When designing the site layout, it is possible that underground utilities such as storm pipes are designed so they will be constructed along a lot line between the houses. In these cases, houses and attached structures should not be built on or over any part of the trench backfill or near enough to the trench where footing stresses will be carried by the backfill. The footing stresses generally extend down and away from the edge of the footings at a 45- degree angle. If it is necessary to construct utilities between lots, additional analysis and recommendations should be completed. C.2.c. Groundwater Control We anticipate that perched groundwater may adversely affect construction. We anticipate sump pumps or other localized methods of temporary dewatering should be suitable for control of ground water. However, more extensive types of dewatering may be necessary if large areas of ground water are encountered or excavations extend to or below the local groundwater level. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 5 C.3. Building Pad Preparation C.3.a. Excavation The proposed building areas should be stripped and cleared of all vegetation, topsoil and fill. All existing utilities, foundations, slabs and other building debris should also be removed from proposed building and oversize areas. Due to the landscaping business that occupied the west part of the site, we recommend a Phase 1 ESA (Environmental Site Assessment) be performed on this site. The foundations can then be supported on the natural soils or properly compacted structural fill. Table 1 lists the recommended excavation depths at the boring locations. Table 1. Recommended Excavation Depths Borina Surface Elevation Recommended Depth of Excavation feet Approximate Bottom Elevation Water Encountered After Drilling Elevation ** ST -1 975.8 6 969 1/2 9691/2 ST -2 978.2 3 1/2 9741/2 962 ST -3 972.6 1/2 972 9691/2 ST-4 971.5 4 9671/2 9641/2 ST -5 978.1 1/2 9771/2 968 ST -6 975.6 4 971 1/2 9691/2 ST -7 977.9 l l * 967 971 ST -8 1 980.5 1 9791/2- 973 1/2 air vc cV4 UdLCU ul Lilt 11GIU w1111 LCSL AILS Or uUnng site gramng ** Short term monitoring level. May not represent a stabilized water level Please note the excavation depths indicated in the above tabulation are approximate and will vary. Excavation depths should be evaluated during testing prior to or during grading. If the excavation within the building area extends below design footing elevation, we recommend the excavation bottoms be extended laterally beyond the edges of the proposed footings a minimum of 1 foot for each vertical foot below the footing at that location (i.e., 1:1 lateral oversizing). This oversizing is necessary for the lateral distribution of the footing loads through the fill. _ C.3.b. Fill and Backfill Fill and Backfill required to bring the site to grade should be placed in thin lifts not exceeding 6 to 12 inches and be compacted to a minimum of 95 percent of the maximum dry density based on the standard Proctor test (ASTM D 698). If lean clay fill is used, it should be placed at a moisture content within 3 percentage points over and no more than 1 percentage point below the soil's optimum moisture content. Sandy fill should be placed at moisture content within 3 percentage points of the soils optimum moisture content. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 6 Based on the laboratory moisture content tests, we anticipate the clay soils will likely need to be dried to achieve the recommended compaction. The contractor should note that moisture conditioning of clay soils could be labor intensive and require significant amounts of time. The on -site topsoil is not suitable for fill or backfill. In addition, imported fill containing bituminous pavement fragments or other foreign debris also should not be used as structural fill. The on -site, non - organic soils encountered in the borings are generally acceptable for use as fill. However, we do not recommend using the fat clay as structural fill. If fill depths exceed 10 feet, the minimum compaction level should be increased to 98 percent. If fill depths exceed 10 feet, a construction delay may also be needed to allow the fill to consolidate. This should be evaluated on a case -by -case basis. Care should be taken when filling over existing slopes that are steeper than 5H:1 V (horizontal to vertical). We recommend benches be excavated into the natural soils of existing slopes that are steeper than 5H:1 V prior to placement. The "stair step " - shaped benches are recommended to key the fill into existing slopes and reduce the risk of fill instability. Benches should be a minimum of 10 feet wide. C.4. Foundation Design CA.a. Bearing Capacity Based on the soil boring results and performance of the above - described soil correction procedures, it is our opinion the natural soils or engineered fill should be suitable for support of the residential structures using spread footings sized for an allowable soil bearing pressure of up to 2,000 pounds per square foot. We recommend that strip footings be at least 20 inches wide and that column pads be at least 3 by 3 feet. This loading should provide a theoretical factor of safety of greater than 3 against localized shearing or base failure of the spread footings. CA.b. Footing Depths Perimeter footings in heated building areas should be founded a minimum of 42 inches below the nearest exterior grade for frost protection. Footings in unheated building or garage areas should be founded a minimum of 60 inches below the nearest exterior grade for frost protection. Attached garages are generally considered heated structures. CA.c. Settlement As noted in section C.2.a, we recommend settlement analysis be completed once additional design information is available. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 7 C.S. Floor Slabs C.5.a. Subgrade After the building pad preparation has been completed, we anticipate the floor subgrade will primarily consist of native clayey soils or compacted fill. Backfill in footing and mechanical trenches should be compacted to a minimum of 95 percent of the standard Proctor maximum dry density. C.5.b. Vapor Barrier Excess transmission of water vapor could cause floor dampness, certain types of floor bonding agents to separate, or mold to form under floor coverings. We recommend placing a vapor retarder or barrier below the ground supported floors. Current industry recommendations are to place the vapor retarder or barrier directly below the concrete. It is then desirable to take precautions against shrinkage and curling of the floor slab. Industry practice has been to allow burying the vapor retarder or barrier below a layer of sand to reduce curling and shrinkage of the concrete, but this practice often traps water between the slabs and the vapor retarder or barrier, causing problems after a period of months. In any case, we recommend consulting with floor covering manufacturers regarding the appropriate type, use and installation of a vapor retarder or barrier to preserve warranty assurances. To reduce shrinkage and curling processes associated with placing concrete directly on the vapor retarder or barrier, we recommend: • using the largest possible maximum aggregate size and/or coarse aggregate. • using the lowest practical slump. • using the lowest necessary cement content to reduce top -to- bottom moisture differentials. • carefully curing the concrete. • optimizing the spacing of control joints. • cutting control joints as soon as practical. We recommend that the vapor barrier be inspected immediately before the concrete is placed to identify and patch holes or other potential paths for moisture vapor migration. C.6. Below Grade Walls C.6.a. Seepage Control If basement walls are constructed, we anticipate they will likely be surrounded by clayey soils. However, sandy soils may also be present along the below grade walls. If water percolates down alongside the walls, it may become perched on an impervious soil layer and then enter the basement through shrinkage Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 8 cracks in the concrete or masonry block. Collecting runoff and discharging it well away from the foundations and sloping the ground surface down and away from the basement walls are two common '— methods of reducing infiltration and percolation. As a precaution against basement seepage, we recommend installing a perimeter foundation drain system. One possible system could include a perforated pipe with an invert within 2 inches of bottom -of- footing elevation. Collected seepage should be routed to a sump and then drained by a pump or gravity to a storm sewer or low area on the site. The seepage control system should include permeable material against the basement wall, such as a synthetic wall drainage system or at least 2 feet (horizontal) of permeable sandy gravel or sand backfill. The sandy gravel or sand backfill should have less than 70 percent passing the number 40 sieve and less than 5 percent passing the number 200 sieve. Some of the on -site poorly graded sands may meet this requirement. Where the sandy gravel or sand backfill extends outside the footprint of the building, it ,^ should be capped by a slab, pavement or at least 1 foot of clay or clayey topsoil. We also recommend that a drainage collection system be installed below the lowest floor grade. The system could include drainage pipe and coarse gravel. Any collected water could then be routed to a sump where it can be removed from the structure. C.6.b. Lateral Earth Pressure Backfill against the basement walls should be compacted to a minimum of 90 percent of the standard Proctor maximum dry density. Beneath steps and slabs, it should be compacted to a minimum of 95 percent. The walls should be waterproofed and braced prior to backfilling. Any below -grade walls will have lateral loads transmitted to them from the surrounding soils. We recommend the following lateral earth pressures be used for below -grade wall design. These values do not include a factor of safety. A factor of safety should be incorporated as part of the design. Table 3. Lateral F,arth Preccnrec* --- o---- r- Active Equivalent At -Rest Equivalent Passive Equivalent Sliding Soil Type Fluid Pressure (pcg Fluid Pressure (pcg Fluid Pressure c Friction SP /SP -SM 30 45 400 .40 Silty/Clayey Soils (SM, 50 70 300 .30 CL) --- o---- r- Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 9 The sandy gravel or sand backfill should have less than 70 percent passing the number 40 sieve and less than 5 percent passing the number 200 sieve. The sand values are also based on the premise that the area 2 feet from the base of the foundation wall and up to the surface at a 60- degree angle from horizontal will be backfilled with poorly graded sand and poorly graded sand with silt. The sand drainage media should ._ be capped with 1 foot of clay or a slab or pavement sloped away from the building to minimize surface infiltration into the sand backfill. C.7. Retaining Walls We understand retaining walls may be constructed on site; however, the locations and type of walls has not been determined. C.7.a. Excavation For retaining wall support, we recommend topsoil, fill and very soft to rather soft native clayey soils be removed from below the proposed retaining wall foundations. After excavation of the unsuitable soils, we anticipate the retaining walls will generally bear on properly compacted structural fill. We also recommend for excavations that extend below design- footing elevation, the excavation bottoms be extended laterally beyond the edges of the proposed wall footings a minimum of 1 foot for each vertical foot below the footing at that location (i.e., 1:1 lateral oversizing). If modular block retaining walls are used, we recommend the lateral oversizing extend outward and downward from the back of the geogrid behind the wall. C.7.b. Foundations Assuming the retaining wall foundations bear on properly compacted structural fill or suitable natural soils, it is our opinion the walls can be supported on strip footings designed using a maximum bearing capacity of 2,000 psf. C.7.c. Backfill Backfill of the walls should generally be done with granular soils. If on -site lean clay soils are used, higher lateral pressures will occur. Also, higher lateral pressures may occur due to frost heave expansion of clayey soils. We recommend backfill placed behind the walls be compacted to a minimum of 95 percent of standard Proctor density. The compaction level should be increased to 100 percent within 3 feet vertically of pavement areas. Small hand - operated equipment should be used to compact the backfill directly behind the walls to avoid excessive deflection of the walls. Backfill in front of the walls should be compacted to a minimum of 95 percent to limit movement. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 10 Drainage behind the walls is critical. Drain tile should be constructed at the bottom of all the wall(s). Either clean sand with less than 5 percent fines passing the number 200 sieve and less than 70 percent passing the number 40 sieve or sandy gravel should be placed behind the wall to promote drainage to the drain tile. We recommend the sand or clean gravel should extend horizontally a minimum of 2 feet away from the back of the wall. C.7.d. Lateral Pressures We recommend the lateral earth pressures provided in Table 3 in Section C.6.6. be used for retaining wall design. These values do not include a factor of safety. A factor of safety should be incorporated as part of the design. C.8. Pavement Areas C.8.a. Subgrade Preparation We recommend the vegetation and organic topsoil be excavated from the pavement areas. Slightly organic fill soils should also be removed within 3 feet of pavement subgrades and replaced with engineered fill below pavement areas. Some additional subcutting of very soft to rather soft native clays may be required and should be anticipated below paved areas. In areas requiring engineered fill to establish pavement grades, the excavation should be oversized at least 1 foot beyond the outside edge of the toe of the roadway embankment for each foot of fill placed below the bottom of the toe of the -- roadway embankment. It should be noted that the clayey soils encountered are frost susceptible. Even if these soils are compacted and appear stable, frost heave may be a problem if water is close to the freeze zone. To minimize potential frost heave, a 2 -foot subcut below subgrade could be made. The subcut should be backfilled with clean sand with less than 5 percent passing the number 200 sieve, and drain tile should be installed. The engineered fill placed in paved areas should be compacted to at least 95 percent of standard Proctor density to within 3 feet of subgrade and 100 percent within the upper 3 feet. We recommend the moisture contents of the engineered fill soils be within 3 percentage points of the optimum moisture content to within 3 feet of subgrade and no greater than 1 percentage point over the soils' optimum moisture content in the upper 3 feet. C.8.b. Proofroll Prior to placement of the pavement section, we recommend the pavement subgrade be proofrolled with a loaded tandem truck to detect unstable areas. Any unstable areas should be subcut and replaced with a drier, compactible soil or dried and recompacted. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 11 C.8.c. Recommended Assumed R -Value Based on the borings, it appears the subgrade soils will range from lean clay to sandy lean clay. However, we anticipate the predominant subgrade soil will be sandy lean clay. These clays typically can have Hveem stabilometer R- values ranging from 8 to 20. We recommend the pavement design be based on a sandy lean clay subgrade using an assumed R -value of 10. Actual laboratory tests to determine the R value were not done as part of this evaluation. C.8.d. Design Sections The City of Chanhassen recommends the minimum pavement design thicknesses listed in Table 5 for urban residential streets. The road design should meet 9 -ton pavement requirements. Based on the assumed subgrade, it is our opinion the recommended minimum pavement sections are suitable for pavement design. Table 5. City of Chanhassen Recommended Minimum Pavement Section Course Urban Residential Street inches Bituminous Wear Course 1 1/2 Bituminous Base Course 2 Gravel Base g Sand Subgrade 24 C.8.e. Recommended Materials We recommend specifying Class 5 aggregate base meeting the requirements of Mn/DOT (Minnesota Department of Transportation) Specification (Standard Specifications of Construction Article) 3138. We recommend bituminous base and wear courses meeting the requirements of Mn/DOT Specification 2360. We recommend the crushed aggregate base be compacted to a minimum of 100 percent of its standard Proctor maximum dry density. We recommend the bituminous mixtures be compacted to a minimum of 95 percent of their Marshall densities. C.9. Utilities C.9.a. Excavation The soils at depth appear generally suitable for pipe support. However, some areas will likely require subcutting of very soft clayey soils and replacement with sand or crushed rock. Organic soils should also be removed from below utilities. Groundwater could adversely affect utility line excavation and installation in some areas of the site. If groundwater is encountered, we anticipate it can likely be controlled with sump pumps within the trench excavations. On -site observations should be made during construction. However, other more extensive types of dewatering may be necessary depending on the depth of the utilities and groundwater levels at the time of construction. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 12 C.9.b. Backfill We recommend that the utility trench Backfill be compacted to the specifications previously outlined in Section C.7. Pavement Areas. However, when the moisture contents of the clayey soils are more than 3 percentage points over the soil's optimum moisture content, the minimum compaction of 95 percent cannot generally be obtained without drying the soils. We then recommend as an alternative that this fill be compacted to a specification described as "zero air voids." For this process, the contractor compacts the soils sufficiently such that the available void spaces within the soil matrix are removed. Zero air voids is acceptable when the soils have been compacted to within 3 pounds of the theoretical maximum density available at the specific moisture content as shown on the Proctor curves for the various soils. However, the minimum density obtained should not be less than 90 percent and zero air voids is not acceptable in the upper 3 feet of subgrade. Zero air voids should not be used under any houses. Using zero air voids could result in some trench settlement. Since the bituminous wear course is usually not placed for at least one year after placing the base course, most settlements could be corrected before the wear course is placed. C.9.c. Corrosion Protection The clay soils are considered slightly to moderately corrosive to metal pipe. Consideration should be given to protecting metal pipes with plastic wrap, sand cover, or cathodic protection. C.10. Additional Investigation and Testing During Construction Prior to the start of grading, we recommend a series of test pits be excavated and/or additional soil borings be taken to further evaluate the subsurface soil and groundwater conditions. _ We recommend a geotechnical engineer or representative be on site during the site grading. At that time, the suitability of the subsurface soils for support of fill and foundation loads can be further evaluated. Excavation depths and provided oversizing can also be documented. Compaction tests should be taken during the site grading operation, utility trench backfilling within the roadway areas, utility trench backfilling near house pad areas and house foundation wall backfill operations. In general, compaction tests should be taken after about 2 feet of fill has been placed in the excavations and then at about 2 -foot vertical intervals thereafter. In roadway subcut areas, we recommend a proofroll be performed before and after placement of the aggregate base. The proofroll should be performed by observing the behavior of the subgrade soils when subjected to the wheel loads of a fully loaded, tandem -axle end dump. These proofrolls should be observed by a geotechnical engineer. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 13 C.11. Cold Weather Construction If site grading and construction is anticipated during cold weather, we recommend that good winter construction practices be observed. All snow and ice should be removed from cut and fill areas prior to additional grading. No fill should be placed on soils that have frozen or contain frozen material. No frozen soils should be used as fill. Concrete delivered to the site should meet the temperature requirements of ASTM C 94. Concrete should not be placed upon frozen soils or soils which contain frozen material. Concrete should be protected from freezing until the necessary strength is attained. Frost should not be permitted to penetrate below footings bearing on frost - susceptible soil since such freezing could heave and crack the footings and/or foundation walls. D. Procedures D.1. Drilling and Sampling We performed the penetration test borings on December 22 and 27, 2005, with an auger drill equipped with 3 1/4 -inch inside - diameter hollow -stem auger mounted on floatation tire drill rig. Sampling for the borings was conducted in general accordance with ASTM D 1586, "Penetration Test and Split- Barrel Sampling of Soils." Using this method, the borehole was advanced with the hollow -stem auger to the _ desired test depth. A 140 -pound automatic hammer falling 30 inches was then used to drive the standard 2 -inch split - barrel sampler a total penetration of 1 1/2 feet below the tip of the hollow -stem auger. The blows for the last foot of penetration were recorded and are an index of soil strength characteristics. A representative portion of each sample was then sealed in a glass jar capped with a lid. D.2. Soil Classification Our drill crew chief visually and manually classified soils encountered in the borings in general accordance with ASTM D 2488, "Description and Identification of Soils (Visual - Manual Procedure)." A summary of the ASTM classification system is attached. All samples were then returned to our laboratory for review of the field classifications by a geotechnical engineer. Representative samples will remain in our office for a period of 30 days to be available for your examination. D.3. Groundwater Observations Immediately after taking the final samples in the bottoms of the borings, the holes were probed through the hollow -stem auger to check for the presence of groundwater. The boreholes were then immediately backfilled. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 14 E. General Conditions E.1. Basis of Recommendations —' The preliminary analyses and recommendations submitted in this report are based upon the data obtained from the soil borings performed at the locations indicated on the attached sketch. Often, variations occur between these borings, the nature and extent of which do not become evident until additional exploration or construction is conducted. A reevaluation of the recommendations in this report should be made after performing on -site observations during construction to note the characteristics of any variations. The variations may result in additional grading costs, and it is suggested that a contingency be provided for this purpose. It is recommended that we be retained to perform the observation and testing program for the site preparation, utility installation, and street construction phases of this project. This will allow correlation of the soil conditions encountered during construction to the soil borings, and will provide continuity of professional responsibility. E.2. Review of Design ... This report is based on the preliminary design of the proposed residential development as related to us for preparation of this report. It is recommended that we be retained to review the geotechnical aspects of the designs and specifications. With the review, we will evaluate whether any changes in design have affected the validity of the recommendations, and whether our recommendations have been correctly interpreted and implemented in the design and specifications. E.3. Groundwater Fluctuations We made water -level observations in the borings at the times and under the conditions stated on the boring logs. These data were interpreted in the text of this report. The period of observation was ,._ relatively short, and fluctuations in the groundwater level may occur due to rainfall, flooding, irrigation, spring thaw, drainage, and other seasonal and annual factors not evident at the time the observations were made. Design drawings and specifications and construction planning should "— recognize the possibility of fluctuations. Cottage Homesteads of Boulder Cove Project BL -05 -06006 January 20, 2006 Page 15 EA Use of Report This report is for the exclusive use of Cottage Homesteads of Boulder Cove, LLC and their design team to use to design the proposed residential development and prepare construction documents. In the absence of our written approval, we make no representation and assume no responsibility to other parties regarding this report. The data, analyses and recommendations may not be appropriate for other structures or purposes. We recommend that parties contemplating other structures or purposes contact us. E.5. Level of Care In performing its services, Braun Intertec used that degree of care and skill ordinarily exercised under similar circumstances by reputable members of its profession currently practicing in the same locality. No warranty, express or implied, is made. Appendix r i � _> K9 -t` ✓_: IYI/! rf vV r�r't.: i•71 r-f c ... _. ._.__ ..,,. .F 'SL r \ 1 a L' - ,`'.tev :x t ] 3,'4fsl > '.. ::51.^ :c \. ,p < i �••-� -,s X:,7;_.6 j= `�..... n., "' Rim 976.79 79 V, i i x3i`_'"_' ?3 i a Inv. - 965.59 Xa752:9 \n ✓L\ ' _y.,•\';75 i sG '-. i \. : >> <:>' :si ,�. °\ ?77..1.' sanit y m hole - ,. \ 9; 5 v ° - \ y9 O ) .__ 1� av X ✓7F..: 3 k ` \ „t, s*.` K J sonitor manhde_ r �. ” OJ Rim 97 4 958.81 ;•,.,°b" N v. 959.3 bit. rood -., '_• L__.^. ics - >"`v"'.^ ^va ti ^`1 ts, � s '` .•t _... �. ..: °. .-,:_. . ` °7 .ri �c q-:r \-._.i , _ F'- 'tea•' .ass . x ,, �Z v+.� •� .�a.� -:s .._ . .1. _ _ - a i#-- �°Y 1 \ 1 t:? \.h ` °gi_ I N In 977.7 \ \ .1 `..\,.3�3. ^... •\. � i._ \ ' -. - ;<- <i -_-_. ._.-. _ _.. .. _._. .... -. .___ ' -_. .. _ �: - x41 ~� _ - - � - y f.\ ... .'\ \ ; 3. _ ' :., ,� n. -:\-'` '`�• 978.13 ; ,\ __j y } `' ✓> - -'a._4 -- t ' a 24 f '_ 1 _ 1 n, 38 I V11 _. }`L:7 !; rah_ } ;_`"� s ,� '` x 3 l j � .c .x \Y 915 57 ' 32 ` c $� } , z: "'.° j \ 1 3 I\ r - -. 5 - -v l GOVEp 2Hi.' J ka ` X 971 5' rr } a1 9T< 4'> 5 .. L iey • G h I ° ._- __ -..� l :z� -t 15' .1;'e'<'s, �� t5� r• J {� _ - R1. \ 5 f ..J `,6 ,7`- „�'� ".' - ..-yt7 ;'%y` t,_, i V11 .xis= i 7. w • �'" !o: 4 1 a - %� F/ J •?r ^'1 Q �p 1 r / f ''• +i X '{''� \- x r->5 / L6 C9”` � rrrs \ i � l ` - { � .. \ :a,�"i5� �'w ;rr, >tTF � 4 - �, � ,' / • Fe E�iSt\ s X 974,9i i <:-% i / ...\r ``7 tl. ' '"` ti`yg. c' � ,✓ <± i /�� j� \ 1 / �'` / � � ~ \,ti �`s z � fi, :� \t. =' � �,� : i"- �- gig �� .-!r� xx�,=, � '- ,'• ._._ _ \ -ti.. �ii .�S /i � �v �: v "':..t/ j �?> 15 •F t sY, ,...% "� �. �i , / \ / / z \ \ t ! ~ /' Iiµ- Q f .$ / / • � £xls>f. q +� � \ . •�- v^.:\s .% i' � `r. ! _.:>�� ,,,%',8E8G zQ� 1k �k i c5 g�:� @�/ t / - � / 1 (� lit 2 55 0,12 la.C,� j95/ / / / ` mix/ -'k '" _ / ' T e / S- 131 Exist 6cserl2enf> S } s r fro&'•- -',,.- / 970_ / �!F 6 Z,. Area = 13.69 Acres DEVELOPER: COTTAGE HOMESTEADS OF AMERICA, INC. ATTNM, ROGER DERRICK 7301 OHMS LANE -SUITE 560 EDINA> MN 55439 PH- 952 -830 -0161 60 0 60 120 1ao Seat -: 1,- 60' DESIGNED DRAWN I HEREBY CERTIFY THAT THIS PLAN, SPECIFICATION, OR REPORT AS PREPARED BY ME OR UNDER MY DIRECT SUPERVISION W" aw PRO £C7 NC C.50. M -L.H. AND i A DULY LICENSED PROFESSIONAL ENGINEER COTTAGE HOMESTEADS AT BOULDER COVE LLC EXISTING CONDITIONS CHECKED R T UNDER THE LAWS OF THE STATE OF MINNESOTA. LA T y�a,i,�s,, T O ? 2-05-0052 No. DATE DESCRIPTION CS.O / �� Fa=Jm) anon CHANHASSEN, MN Coro M. Schwohn oito SHEET NO. 1 OF 1 SHEETS DATE 1105106 REVGONS LICENSE 40433 DATE: E s wd Lana Swveywy, bw. G i BRAUN "' I NTE RTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -1 GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Cottage Homesteads at Boulder Cove, LLC 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: Mark Barber METHOD: 3 1/4" HSA Autohammer DATE: 12/22/05 SCALE: 1" =40 Elev. Depth feet feet ASTM Description of Materials BPF WL MC qu Tests or Notes 975.8 0.0 Symbol (ASTM D2488 or D2487) % tsf CL LEAN CLAY with SAND, dark brown, frozen to wet. Benchmark: The (Topsoil/Possible Fill) soil borings were 973.8 2.0 4 3/4 staked by Braun Intertec and the elevations were SC CLAYEY SAND, wet, rather soft. (Alluvium) measured by Otto 971.8 4.0 Associates. CH FAT CLAY, with lenses of Silt, light olive gray to gray, wet, rather soft to medium. 4 3/4 (Alluvium) n = A solid triangle "- indicates the 7 1 1/4 groundwater level in the boring on the date indicated. 7 38 DD = 85 pcf i i n 7 7 i i 1 i I 4 Q An open triangle in the water level 953.8 22.0 (WL) column indicates the depth at which CL LEAN CLAY, with Sand and Gravel, gray, wet, rather soft. (Glacial Till) groundwater was observed while drilling. 5 Groundwater levels 950.3 25.5 fluctuate. END OF BORING. Water observed at 20 feet with 24 feet of hollow -stem auger in the ground. Water observed at 6 feet immediately after withdrawing the auger. ar nc ncnn< Boring immediately backfilled. ST -1 page 1 of I E 0 r c F C E 0 P C a a BRAUN"' INTERTEC LOG OF BORING Braun Project BL-05 -06006 BORING: ST -2 GEOTECHNICAL EVALUATION Cottage Homesteads at Boulder Cove, LLC LOCATION: See attached sketch. 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: Mark Barber METHOD: 3 1/4" HSA Autohammer DATE: 12/22/05 SCALE: 1" = 4' Elev. Depth feet feet ASTM Description of Materials BPF WL qu Tests or Notes 978.2 0.0 Symbol (ASTM D2488 or D2487) tsf FILL FILL: Silty Sand, frozen to moist. (Possible Fill) 976.2 2.0 7 SM SILTY SAND, black, wet, medium. (Topsoil) 9 74.7 3.5 CH FAT CLAY, with lenses of Silt, brown, wet, medium. (Alluvium) 7 1 1/2 i 3 i 8 i 1 8 ' 966.7 11.5 MLS . SANDY SILT, brown, wet, medium. s (Alluvium) 6 6 i 960.2 18.0 CL SANDY LEAN CLAY, brown to gray, wet, medium. (Glacial Till) 6 1 952.7 25.5 7 END OF BORING. Water observed at 16 feet immediately after withdrawal of auger. Boring immediately backfilled. ..agate wlpulauun, oiuumingwn si -Z page 1 of 1 i J J r 4 1 s - �. i - - F a a r r a a U C r G c E a 0 C C V a G BRAUN`" i NTE RTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -3 GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Cottage Homesteads at Boulder Cove, LLC 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: METHOD: 3 1/4" HSA Autohammer DATE: 12/27/05 SCALE: 1 -1 = 41 Elev. Depth feet feet ASTM Description of Materials BPF WL MC qu Tests or Notes 972.6 0.0 Symbol (ASTM D2488 or D2487) % tsf 972.1 0.5 SC CLAYEY SAND, dark brown, frozen to moist. (Topsoil) SM :: SILTY SAND, fine- to medium - grained, brown, moist to wet, loose. (Alluvium) 5 27 p200 = 49% 1 7 966.6 6.0 CH FAT CLAY, with lenses of Silt, brown to gray, wet, rather soft to medium. (Alluvium) 7 S i 3 39 DD = 84 pcf 7 7 i L I 6 1 952.1 20.5 END OF BORING. Water not observed with 19 feet of hollow -stem auger in the ground. Water observed at 3 feet immediately after withdrawal of auger. Boring immediately backfilled. — 1111UD1 WA %.Vl PUI 6UU11, mumunpon s t -s page i of c — E c f z F C C E 0 0 yC 2 C V a a BRAUN" I NTE RTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -4 GEOTECHNICAL EVALUATION Cottage Homesteads at Boulder Cove, LLC LOCATION: See attached sketch. 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: METHOD: 3 1/4" HSA Autohammer DATE: 12/27/05 SCALE: 1" = 4' Elev. Depth feet feet ASTM Description of Materials BPF WL Tests or Notes 971.5 0.0 Symbol (ASTM D2488 or D2487) 970.9 0.6 SC CLAYEY SAND, coarse grained, dark brown, frozen to wet. SC Possible Fill CLAYEY SAND, gray, rather soft. (Alluvium) 4 967.5 4.0 CL LEAN CLAY with SAND, brown, wet, medium. (Alluvium) 7 965.0 6.5 1 d CH FAT CLAY, with lenses of Silt, gray, wet, medium. U (Alluvium) 7 5 a 3 g g S i n 7 956.0 15.5 8 END OF BORING. Water not observed with 14 feet of hollow -stem auger in the ground. Water observed at 7 feet immediately after withdrawing the auger. Boring immediately backfilled. .,.a.,., a1no1— w vviauun, nnrummgwn ST-4 page 1 of 1 r. G i F C C' E 0 a yC Z C V a BRAUN'" INTERTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -5 GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Cottage Homesteads at Boulder Cove, LLC 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: METHOD: 3 1/4" HSA Autohammer DATE: 12/27/05 SCALE: V = 4' Elev. Depth feet feet ASTM Description of Materials BPF WL MC Tests or Notes 978.1 0.0 Symbol (ASTM D2488 or D2487) % 977.4 0.7 SC CLAYEY SAND, dark brown, frozen. (Topsoil) SM SILTY SAND, dark brown, moist. (Alluvium) 12 8 p200=21% 8 0 b '> 4 8 e 969.6 8.5 CH FAT CLAY, with lenses of Silt, brown. 3 (Alluvium) 9 1 u n 7 962.6 15.5 8 38 DD = 84 pcf END OF BORING. Water not observed with 14 feet of hollow -stem auger in the ground. Water observed at 10 feet immediately after withdrawing the auger. Boring immediately backfilled. AT _"_Ard" ..__. vv.�.v...uva5 a�awaaauaswaa 61-3 page r or i U F C C E a 6 a C C V a a BRAUN'" I NTE RTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -6 GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Cottage Homesteads at Boulder Cove, LLC 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: Mark Barber METHOD: 3 1/4" HSA Autohammer DATE: 12/22/05 SCALE: P = 4' Elev. Depth feet feet ASTM Description of Materials BPF WL qu Tests or Notes 975.6 0.0 Symbol (ASTM D2488 or D2487) tsf FILL FILL: Silty Sand, brown, frozen to moist. 974.6 1.0 FILL FILL: Silty Sand, fine- to medium - grained, brown, moist. 18 971.6 4.0 SC CLAYEY SAND, brown, wet, rather stiff. (Alluvium) 9 969.1 6.5 1 g CH FAT CLAY, with lenses of Silt, brown, wet, soft to rather stiff. 9 a (Alluvium) 3 a 4 1 a e i 3 3 960.1 15.5 g END OF BORING. Water not observed with 14 feet of hollow -stem auger in the ground. Water observed 6 feet immediately after withdrawing the auger. Ot AL ALML Boring immediately backfilled. a.v,N --, --ugwu Zi I -b page t of I BRAUN" INTERTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -7 GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Cottage Homesteads at Boulder Cove, LLC 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: James Krohn METHOD: 3 1/4" HSA Autohammer DATE: 12/27/05 SCALE: 1 r' =41 Elev. Depth feet feet ASTM Description of Materials BPF WL MC qu Tests or Notes 977.9 0.0 Symbol (ASTM D2488 or D2487) % tsf 977.1 0.8 FILL FILL: Clayey Sand, brown, frozen to wet. CL LEAN CLAY with SAND, black, wet, rather soft. (Topsoil) 4 974.4 3.5 CH FAT CLAY, with lenses of Silt, brown to gray, wet, rather soft to medium. (Alluvium) 4 3/4 c 0 1 4 37 1/2 m w 0 a 0 5 3/4 x d w 0 6 1 bi 0 0 7 962.4 15.5 END OF BORING. Water not observed with 14 feet of hollow -stem auger in Athe ground. Water observed at 7 feet immediately after withdrawing the auger. Boring immediately backfilled. 8 g N ca m d `z j U a m a m BL -05 -06006 Braun Intertec Corporation, Bloomington ST -7 vase 1 of 1 i i ci i i F A U i; V G f F C C E tl 0 Cy 2 C `u a Q BRAUN"' I NTE RTEC LOG OF BORING Braun Project BL -05 -06006 BORING: ST -8 GEOTECHNICAL EVALUATION Cottage Homesteads at Boulder Cove, LLC LOCATION: See attached sketch. 62nd Street & Strawberry Lane Chanhassen, Minnesota DRILLER: METHOD: 3 1/4" HSA Autohammer DATE: 12/27/05 SCALE: 1rr = 4' Elev. Depth feet feet ASTM Description of Materials BPF WL MC Tests or Notes 980.5 0.0 Symbol (ASTM D2488 or D2487) % 979.7 0.8 SC CLAYEY SAND, dark brown, frozen to wet. (Topsoil) SC CLAYEY SAND, dark brown, wet, rather stiff. XXX (Alluvium) 9 976.5 4.0 CL SANDY LEAN CLAY, rather stiff. (Alluvium) 10 974.0 6.5 1 CH FAT CLAY, lenses of Silt, brown to gray, wet, medium. (Alluvium) J 6 34 PI = 20 LL 53 i i i 7 i i i i 8 i 965.0 15.5 7 END OF BORING. Water not observed with 14 feet of hollow -stem auger in I the ground. Water observed at 7 feet immediately after withdrawing the auger. Boring immediately backfilled. mauu unerrec t,orporauon, moommgron STA page 1 of 1 Descriptive Terminology Rev 10104 Standard D 2487 - 00 Classification of Soils for Engineering Purposes u � .IL .r�r, � :� (Unified Soil Classification System) Li t L.i a a u Criteria for Assigning Group Symbols and Soils Classification Group Group Names Using Laboratory Tests a Specific gravity Symbol Group Name " °_ o Gravels Clean Gravels C° >_ 4 and 1 : C° ! 3 c GW Well -graded grave o c More than 50 °� of coarse traction Less than 5% fines ° C< 4 and/or 1> C> 3° GP p acted gravel' y gr gro e m m m 'y retained on Gravels with Fines Fines Bassi as ML or MH GM Si gravel Fines classify as CL or CH GC Clayey gravel a r e -° 5000 No. 4 sieve More than 12% fines ° sro r Sands Clean Sands C. >_ 6 and I : C < 3 ° SW Well -Waded sand" tz 50% or more of traction Less than 5% fines ' C < 6 and/or I > C > 3 c ° c SP Poorly graded sand " ii o coarse passes Sands with Fines Fines classify as ML or MH SM Silty sand r9" E No. 4 sieve More than 12 %' Fines classify as CL or CH SC Clayey sand m c Silts and Clays Inorganic PI > 7 and plots on or above 'A" line 1 CL Lean clay < 4 or plots below "A" tine 1 ML Silt 11 i m ® limit Organic Liquid limit - oven dried < 0.75 OL Organic day 1 % 'm m .y less Ilm 50 CL 0 d' Liquid limit - not dried OL Organic silt 6 `, ° Silts and clays Inorganic PI plots on or above "A" line CH Fat clay PI plots below "A" line MH Elastic silt k i m o z Liquid Emit 0 50 or more Organic Liquid limit - oven dried OH Organic day " " ° 1° < 0.75 Liquid limit - not dried OH Organic silt'` r " v Highly Organic Soils Primarily organic matter, dark in color and organic odor PT Peat a. Based on the material passing the 3-in (75mm) sieve. b. If field sample contained cobbles or boulders, or both. add with cobbles or boulders or both" to group name. c. Cu = D. / D10 C� = (D,")2 D10 x D. d. If sod contains >_ 15% sand. add "with sand- to group name. e. Gravels wilih 5 to 12% fines require dual symbols: GW-GM weWgraded gravel with sift ,.., GW-GC well-graded gravel with day GP-GM poorly graded gravel with silt GP -GC poorly graded gravel with day f- If fines classify as CL-ML. use dual symbol GC-GM or SC-SM. % If fines are organic. add 'with organic lines' to group name. h. If soil contains >_ 15% gravel, add 'with gravel' to group name. —i. Sands with 5 to 12% lines require dual symbols: SW -SM well-graded sand with silt SW -SC well-graded sand with day SPSM poorly graded sand with silt SP -SC poorly graded sand with day j. If Atterberg limits plot in hatched area, soil is a CL -ML, silty day. ... k. If sal contains 15 to 29% plus No. 200, add "with sand" or 'with gravel' whichever is predominant. L If sod contains > 30% plus No. 200. predominantly sand. add "sandy" to group name. m. if soil contains > 30% plus No. 200 predominantly gravel, add "gravelly" to group name. n. PI > 4 and plots on or above W line. o. PI < 4 or plots below 'A" line. _p- PI plots on or above "A" fine. q- PI plots below 'A" line. 60 50 40 a- -+D 30 7 U 20 0 0 D 'D w,C LL AlL 10 7 4 00 ?000 10 16 20 30 40 Dry density, pcf Wet density. pct Natural moisture content, % Ligtuid limit, % Plastic limit, % Plasticity index, % % passing 200 sieve 50 60 70 80 90 100 110 Liquid Limit (LL) Laboratory Tests OC Organic content, % S Percent of saturation, % SG Specific gravity C Cohesion, psf 0 Angle of internal friction qu Unconfined compressive strength, psf q Pocket penetrometer strength, tsf Fine ......-- ------------ _-- -- - - - -- No. 40 to No. 200 Silt ... ... ....... .......... ........ . . . . .- <W. 200. PI <4 or below 'A" line Clay ....... .. . .. --- _- - - - - -- <No. 200. PI>4 and J on or above "A" tine Z' ,' G i ' d' G\' MH OH MH or OH 10 7 4 00 ?000 10 16 20 30 40 Dry density, pcf Wet density. pct Natural moisture content, % Ligtuid limit, % Plastic limit, % Plasticity index, % % passing 200 sieve 50 60 70 80 90 100 110 Liquid Limit (LL) Laboratory Tests OC Organic content, % S Percent of saturation, % SG Specific gravity C Cohesion, psf 0 Angle of internal friction qu Unconfined compressive strength, psf q Pocket penetrometer strength, tsf Particle Size Identification Boulders - - ---- .....----------------- over 12" Cobbles .. ............................. 3" to 12" Gravel 11 to 30 BPF Coarse ._- ....._ .. ............... 314" to 3" Fine .. ....... ........................ Sand No. 4 to 3/4" Coarse - - ----._- - - -------- - - - --- No_ 4 to No. 10 Medium - - --- ---------------- - - - - -- No. 10 to No. 40 Fine ......-- ------------ _-- -- - - - -- No. 40 to No. 200 Silt ... ... ....... .......... ........ . . . . .- <W. 200. PI <4 or below 'A" line Clay ....... .. . .. --- _- - - - - -- <No. 200. PI>4 and on or above "A" tine Relative Density of Cohesionless Soils Very loose -------- --- -- ---- --- ----- -----0 to 4 BPF Loose ...................... ................. 5 to 10 BPF Medium dense .......................... 11 to 30 BPF Dense ....................................... 31 to 50 BPF Very dense ---- ---- ------ ------- - - - -- ------ over 50 BPF Consistency of Cohesive Soifs Very soft---- --- --------- -- ------ --- ----- --0 to 1 BPF Soft - --------- -- - - -- --- ----------- ........ 2 to 3 BPF Rather soft .. ......................... . ....4 to 5 BPF Medium ------- ------------ ----- -------- -----6 to 8 BPF Rather stiff -------------------------------- 9 to 12 8PF Stiff ........ ............................... 13 to 16 BPF Very stiff ------------------------------------ 17 to 30 BPF Hard .... ---- - ---- ------ --- --- ---- --- --- -...over 30 BPF Drilling Notes Standard penetration test borings were advanced by 3u "" or 6G" ID hollow -stem augers unless noted otherwise, Jetting water was used to dean out auger prior to sampling only where indicated on togs. Standard penetration test borings are designated by the prefix "ST' (Split Tube). All samples were taken with the standard 2" OD split -tube sampler, ex- cept where noted. Power auger borings were advanced by 4" or 6" diameter continuous- flight, solid -stem augers - Sod classifications and strata depths were in- ferred from disturbed samples augered to the surface and are, therefore, somewhat approximate. Power auger borings are designated by the prefix'8 " Hand auger borings were advanced manually with a 1 or 3?" diam- eter auger and were limited to the depth from which the auger could be manually wittndrawn. Hand auger borings are indicated by the prefix'H " BPF: Numbers indicate blows per foot recorded in standard penetration test, also known as 'N" value. The sampler was set 6" into undisturbed soil below the hollow -stem auger. Driving resistances were then counted for second and third 6" increments and added to get 8PF. Where they differed significantly, they are reported in the following form: 2/12 for the second and third 6" increments, respectively. WH: WH indicates the sampler penetrated soil under weight of hammer and rods alone; driving not required. WR WR indicates the sampler penetrated soil under weight of rods alone; hammer weight and driving not required. TW indicates thin -walled (undisturbed) tube sample. Note: Ali tests were run in general accordance with applicable ASTM standards. BRAUN I NTE RTEC