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HomeMy WebLinkAbout2001 Geotechnical Evaluation Report 15) PLU�11M„ V A Geotechnical Evaluation Report for RVC Homes Proposed House 1080 Wildhurst Trial Orono, Minnesota Project BABX-01-0124 April 12, 2001 Braun Intertec Corporation B R A U NSM Braun Intertee Corporation 6801 Washington Avenue South Minneapolis,Minnesota 55439 INTE RT E C 612-941-5600 Fax:941-4151 Engineers and Scientists Serving the Built and Natural Environment? April 12, 2001 Project BABX-01-0124 Mr. Rick Vogelgesang RVC Homes 900 Twelve Oaks Center Drive Minnetonka, MN 55391 Dear Mr. Vogelgesang: Re: Geotechnical Evaluation, Proposed House at 1080 Wildhurst Trail, Orono, Minnesota As you authorized, we have completed the geotechnical evaluation for the proposed house at 1080 Wildhurst Trail in Orono, Minnesota. The purpose of the geotechnical evaluation was to assist in evaluating the subsurface soil and groundwater conditions with regard to construction of the house. Our work was performed in general accordance with the Authorization of Services you signed. Summary of Results The two borings performed on this site, and the two borings performed in the neighboring lot, indicate soil conditions generally consist of old fill soils over soft, compressible organic soils to depths of about 19 to 35 feet. Excavations in excess of 15 feet are typically not economical, and in this case high groundwater would cause extreme difficulty and may prevent successful excavation of unstable soils. Summary of Recommendations If the new house is constructed where it is currently designed to be, we recommend the house and floor slab be designed to be supported by a deep foundation system consisting of closed-end driven pipe piling. Due to the depths of soft organic soils, it is our opinion an excavate backfill approach would not be feasible. Due to the high groundwater, we recommend the lowest floor slab elevation be at 933 or about 4 feet above the estimated static groundwater table. We recommend considering using a moisture barrier under the floor slab. We recommend the pile caps, grade beams, and foundation walls be backfilled with a clean granular material to reduce the potential effects for negative loading related to settlement. We also recommend the exterior features such as drive apron, sidewalks and landscaping be designed to tolerate settlement. If a raise in grade of more than a few feet is made, we recommend surcharging the new fill and/or delaying construction of these non-pile supported elements and monitoring settlement during a period of time. Completion of exterior features such as slabs, sidewalks, and drive aprons may have to wait until induced settlement significantly slows. RVC Homes Project BABX-01-0124 April 12, 2001 Page 2 General Please refer to the attached report for a more detailed summary of our analysis and recommendations. Thank you for the opportunity to be of service on this project. If we can provide additional assistance or observation and testing services during construction, please call Gregg Jandro at (952) 942-1766 or Gregory Glitto at(952) 942-4841. Sincerely, Braun Intertec Corporation 1 Gregory Glitto, P.E. Project Engineer e:7-Z I . dro, P.E. Senior Principal Engineer Attachment: Geotechnical Evaluation Report ep-eng\sys\wpdata\baba\01-120\georpt gjg/gd:Paa Table of Contents Description Page A. Introduction 1 A.1. Project 1 A.2. Purpose 1 A.3. Scope 1 A.4. Information Provided 1 A.S. Locations and Elevations 2 B. Results 2 B.1. Logs 2 B.2. Soils Encountered 2 B.3. Groundwater 3 C. Analyses and Recommendations 3 C.1. Proposed Construction 3 C.2. Discussion 4 C.3. Driven Piling 4 C.4. Pile Foundations 5 C.S. Pile cap, Grade Beam and Foundation Wall Backfill 7 C.6. External Features 7 C.7. Surcharging..._ 8 D. Construction 8 D.1. Pile Hammer 8 D.2. Test Piles 8 D.3. Production Pile Observations 8 D.4. Backfills 9 D.S. Backfill Compaction Testing 9 D.6. Settlement Plate Monitoring 10 D.7. Cold Weather 10 E. Procedures 11 E.1. Drilling and Sampling 11 E.2. Soil Classification 11 E.3. Groundwater Observations 1 I F. General Recommendations 11 F.1. Basis of Recommendations 11 F.2. Review of Design 12 F.3. Groundwater Fluctuations 12 F.4. Use of Report 12 F.S. Level of Care 13 Professional Certification Appendix Boring Location Sketch Log of Boring Sheets ST-I and ST-2 Descriptive Terminology B R A I I N' Braun Intertec Corporation 6801 Washington Avenue South N T E RT E C Minneapolis,Minnesota 55439 612-941-5600 Fax:941-4151 Engineers and Scientists Serving the Built and Natural Environment? A. Introduction A.1. Project We understand that a single-family residence is planned for 1080 Wildhurst Trail in Orono, Minnesota. A single-family residence is also planned on the neighboring lot at 1074 Wildhurst Trail. Two standard penetration soil test borings were performed at 1074 Wildhurst Trail and at 1080 Wildhurst Trail. A.2. Purpose The purpose of the soil borings was to evaluate the subsurface soil and groundwater conditions at this site in the area of the new residential construction. The information will be used by you and your design team to prepare plans and specifications for the new house. A.3. Scope Our geotechnical evaluation was performed in general accordance with our Authorization for Services you signed. Our scope of services consisted of the following: • Staking the boring locations and determining ground surface elevations at the boring locations; • coordinating the locating of underground utilities near the boring locations; • conducting two penetration test borings to nominal depths of 40 to 60 feet; • classifying the samples and preparing boring logs; • formulating recommendations for driven piling foundations: and • submitting a geotechnical evaluation report containing logs of the borings, our analysis of the field tests, and recommendations for driven pile foundations. A.4. Information Provided You provided us with a"Lot Survey' including elevations of sanitary manhole covers located just north of the north lot line. The survey shows lot lines. a proposed building footprint, proposed driveway, and existing garage. RVC Homes Project BABX-01-0124 April 12, 2001 Page 2 Prior to the start of our soil borings, a test pit was excavated near the west building line of the house. The test pit was extended to approximately 15 feet below the surface and indicated that the soft or unsuitable soils may extend below the 15-foot depth. Also,prior to the start of soil borings,two deep standard penetration test borings were completed at the adjoining lot at 1074 Wildhurst Trail. These neighboring borings indicate soft and organic soils extend to depths of 27 to 32 feet below the surface. A.5. Locations and Elevations The borings were completed at the approximate locations shown on the attached sketch. These locations were selected and staked in the field by Braun Intertec. Ground surface elevations at the borings were measured by Braun Intertec referencing the eastern-most sanitary manhole cover located just north of the north lot line. B. Results B.1. Logs Log of Boring sheets indicating the depths and identifications of the various soil strata, penetration resistances, laboratory test data 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. B.2. Soils Encountered Two standard penetration test borings were completed for the proposed house. Boring ST-1. located near the southwest proposed building area, encountered approximately 12 feet of fill. The fill consisted of lean clay and lean clay with sand, brown to black, and moist. Penetration resistance (N-values) ranged from 23 to 9 blows per foot (BPF), indicating the fill is variably compacted. Below the fill, the boring encountered 7 feet of sandy lean clay and lean clay,judged to be possible fill over slopcwash. RVC Homes Project BABX-01-0124 April 12, 2001 Page 3 From a depth of about 19 feet to the boring termination depth of 30 1/2-feet,the boring encountered clayey sand and sandy lean clay glacial till. N-values in the glacial till ranged from 10 to 16 BPF, indicating the sandy lean clay to be in a rather stiff consistency and the clayey sand to be medium dense to loose. Boring ST-2, located near the northeast proposed building area, encountered about 11 feet of fill over a 2-foot thick layer of peat. The fill is a mixture of lean clay with sand,topsoil, silty sand, and clayey sand. N-values in the fill average about 3 BPF, indicating it is poorly compacted. Below the fill and peat, the boring encountered a variety of slopewash and lacustrine soils to a depth of about 33 feet. These soils consist of silty sand, organic silt and organic clay. N-values range from weight of hammer to 2 BPF, indicating these soils are very loose or very soft. Below the slopewash and lacustrine soils, the boring encountered glacial till to the borings termination depth of 60 1/2-feet. The glacial till consist of clayey sand and lean clay with N-values ranging from 5 BPF at 40 feet and gradually increased to 18 BPF at 60 feet. Large gravel, cobbles or boulders are also common to glacial till soils. B.3. Groundwater When groundwater was encountered during drilling or sampling its depth was measured within the hollow-stem auger. Water level measurements were also made immediately after the auger was removed. The borings were then backfilled with quickset grout in Boring ST-2. Groundwater was not observed in Boring ST-1. Groundwater was encountered during drilling or sampling at an elevation of about 925 in Boring ST-2 or at an elevation of about 922 1/2 after removal of the hollow-stem auger. Because of the relatively impermeable nature of the soils encountered, it is our opinion the measured water level after the auger was removed is below the true static groundwater level. It is our opinion the actual static groundwater elevation lies somewhere above or within the peat zone or at an elevation between 929 and 924 1/2. It is likely the groundwater level is closely related to the level of Lake Minnetonka, which we understand is now 929. This corresponds with the groundwater elevations observed in the borings taken at 1074 Wildhurst Trial. Annual and seasonal fluctuations of the groundwater level should be anticipated. C. Analyses and Recommendations C.1. Proposed Construction We understand the proposed house is a single-family residential structure with a walkout basement to the east. At this time, the house location is shown on the attached boring location sketch. However, we understand the house location may be moved closer to Wildhurst Trail. We assume the site grades will RVC Homes Project BABX-01-0124 April 12, 2001 Page 4 not be changed by more than a few feet, however, recommendations are provided if large grade changes are anticipated. At this time we estimate the lowest floor slab elevation will be about 935 C.Z. Discussion Based on the results of our soil borings and our understanding of the proposed construction, it is our opinion the near-surface soils are not suitable to support typical spread footing foundations. The old fill, slopewash soils and organic soils will likely settle in time,which would lead to foundation and structural damage. It is our experience that driven piling is generally a more economical foundation solution, as compared to an excavation/backfill approach when excavation depths exceed 15 feet. Based on the borings,the excavation depth would likely exceed 30 feet. The high water table, coupled with deep excavations, makes the excavation/backfill soil correction approach difficult, expensive and, in our experience, not feasible. We recommend the proposed house, including the lowest floor slab, be supported by a deep foundation system. A deep foundation system will bypass the soft or unsuitable soils,transferring the building loads to competent bearing soils at depth. Several deep foundation systems are available,however, it is our opinion driven closed-end pipe-pile would be the most economical. A helical anchor system can be looked at, however the length of the anchor and the poor lateral support for the anchor shafts may preclude use of anchors. A specialty contractor could be contacted to address the feasibility and cost of helical anchors at this site. C.3. Driven Piling Building loads, or a desired pile capacity,were not available for this report. Building loads for single-family homes are generally light. Typical net working pile capacities for residential construction are in the range of 20 to 35 tons per pile. For the purpose of this report, we have generated pile length estimates that provide net working capacities of 25 and 50 tons per pile. The purpose of evaluating the 50-ton pile design is that the additional capacity can be achieved with a relatively small increase of pile length over that of the 25-ton pile design. Using a 50-ton pile design could decrease the total number of pile required resulting in a cost savings. If desired additional pile length estimates can be evaluated for other pile capacities or other pile types and sizes. If the assumed loads exceed these values, if the building grades differ by more than 1 foot or if the location of the proposed house additions changes, we should be informed. Additional analyses and revised recommendations may be necessary. RVC Homes Project BABX-01-0124 April 12, 2001 Page 5 • C.4. Pile Foundations We have reviewed several pipe pile sizes that are commonly used to provide the recommended pile capacities in soil conditions similar to this project. Other suitable pile types may also be available and pile-driving contractors often offer alternate pile as part of their bid. If an alternate pile type is proposed, we would be pleased to provide our analysis and opinion as to the suitability of the alternate pile for the project. We chose two commonly used pipe sizes for our analysis,they are 12 3-4-inch OD and 9 5/8-inch OD pipe. These pile sizes also correspond to those offered by Atlas Foundation Company. C.4.a. Allowable Positive Geotechnical Capacities. Allowable positive geotechnical pile capacities are determined by dividing the ultimate positive geotechnical pile capacities by a factor of safety. The American Association of State Highway and Transportation Officials (AASHTO) recommend the safety factor be related to the degree of construction control. A listing of the factors of safety is provided in Table 1. Table 1. Recommended Factors of Safety Specified Construction Control Factor of Safety Dynamic formula 3.50 Wave equation(computer analysis with hammer and driving data) • 2.75 Wave equation and Pile Dynamic Analyzer(PDA) 2.25 Static load test and dynamic formula, wave equation and/or PDA 2.00 Wave equation. PDA and static load test 1.90 Based on Table 4.5.6.2A of AASHTO's Standard Specifications for Highway Bridges, 1996 C.4.b. Ultimate Positive Geotechnical Capacities. We used a combination of methods including DRIVEN to predict the ultimate positive geotechnical vertical static capacities of piles. DRIVEN is a computer program developed for the Federal Highway Administration. We assumed the pile cut-off elevations will be approximately 4 feet below the lowest level slab elevation; i.e., we assumed the cutoff elevations will be about 929. We also assume a static pile load test would not be economically feasible for a project of this size, therefore pile lengths given assume the AASHTO recommended safety factor would be 2.25 when using the wave equation analysis and dynamic pile testing to judge pile capacity. • RVC Homes Project BABX-01-0124 April 12, 2001 Page 6 We would like to note that there are numerous methods of predicting the static capacities of piles based on the results of borings, and that the results of the various methods often differ by a factor of two or more. In other words, predicting the static capacities of piles is not an exact science. We used the methods that appear to provide reasonable results based on our experience with pile length estimates and actual field results. It should also be kept in mind that measuring the ultimate capacity of a pile after it has been installed is also not an exact science. The measured capacity depends on the method used(dynamic formula, wave equation, Pile Dynamic Analyzer(PDA) or static load test)and the criteria used with each method. C.4.c. Estimated Pile Lengths. The estimated pile lengths given below in Table 2 are to provide pile suitable of providing up to 25-or 50-ton net working loads with a factor of safety of at least 2.25. The lengths assume the design cut-off elevation will be at an elevation of 929. Keep in mind the interior pile could be designed to have a pile cut-off elevation of about 931 or 932 thus increasing the required pile length by about 2 to 3 feet. Table 2. Estimated Pile Lengths Pile Assumed Estimated Estimated Estimated Net Working Size Cut-Off Downdrag Pile Length Pile Toe Capacity Boring (inches) Elevation (tons) (feet) Elevation (tons) ST-1 12.75 929 0 25 — 30 904— 899 25 ST-1 9.625 929 0 35 —40 894— 889 25 ST-2 12.75 929 17 45 — 50 884 — 879 25 ST-2 9.625 929 11 55 — 60 874— 869 25 ST-1 12.75 929 0 45 — 50 884— 879 50 ST-1 9.625 929 0 55 — 60 874— 869 50 ST-2 12.75 929 17 65 — 70 864 — 859 50 ST-2 9.625 929 11 75 — 80 854— 849 50 C.4.d. Pipe Pile Specifications. We recommend the pipe piles have a minimum wall thickness of 7/32 inches and the steel material meets specifications for ASTM A252 Grade 11. ASTM A252 Grade II requires the steel material to have a minimum steel yield strength of 36,000 pounds per square inch (psi). The piles should be driven closed end with plates welded to the toe of the piles. The end plates should have a minimum thickness of 1/2 inch. • RVC Homes Project BABX-01-0124 April 12, 2001 Page 7 C.4.e. Frost Protection. In heated areas, we recommend the perimeter pile caps and grade beams extend a minimum of 3 1/2 feet below exterior grade for frost protection. Interior pile caps and grade beams may be placed immediately beneath the slab unless foundation construction will take place during the winter. During winter construction, pile caps and grade beams should be placed a minimum of 5 feet below grade to be protected from freezing. In unheated areas, we recommend the pile caps and grade beams also be placed a minimum of 5 feet below grade. C.4.f. Settlement. We anticipate total and differential settlement of the piles will be less than 1/2 inch and 1/4 inch, respectively, under the assumed loads. C.4.g. Concrete Fill. We recommend the piles be filled with concrete. This will increase their stiffness and load carrying capacities, and aid in maintaining the pile strength if the steel shell partially corrodes. We recommend the concrete have a minimum 28-day compressive strength of 2,500 pounds per square inch. C.5. Pile cap, Grade Beam and Foundation Wall Backfill To minimize the risk of excessive negative loading on foundation walls, pile caps and grade beams due to consolidation of the underlying soft, loose or organic soils, we recommend backfill placed around these structural elements consist of poorly graded sand with less than 5 percent passing the number 200 sieve. This material should extend a minimum of 2 feet away from the backfilled building elements. A 1-foot thick layer of clayey topsoil, slab, or pavement should cap the granular backfill at the surface. C.6. External Features Due to thick deposits of soft organic soils, it is likely the ground surfaces at the site will settle continually, however, the rate of settlement should decrease with time. The amount of settlement can be reduced by minimizing raises in grade. We recommend external features be designed to tolerate continual settlement of the general area surrounding the house. Driveway aprons and sidewalks should be hinged at the structure to prevent development of tripping hazards. These items should be structurally designed. Connections of the underground utilities should be made flexible. especially at the house connection. RVC Homes Project BABX-01-0124 April 12, 2001 Page 8 C.7. Surcharging Unacceptable amounts of settlement may occur, especially if more than a few feet of additional fill is placed. To reduce future settlements, we recommend a surcharge be placed exceeding the desired final grade elevation, and the elevation of the surcharged be monitored over a period of time. After the rate of settlement has decreased,the surcharge can be removed and exterior features constructed. D. Construction D.1. Pile Hammer We recommend the piles be driven using a hammer with a manufacturer's rated energy ranging from 15,000 to 30,000 foot-pounds and be capable of transferring 7,000 to 15,000 foot-pounds of energy. Care must be taken not to overstress (and possibly damage)the piles. Prior to acceptance, we recommend a wave equation analysis be performed to evaluate the contractor's proposed driving system. D.2. Test Piles We recommend pile capacity be determined using wave equation analysis and dynamic pile tests. As shown above, with the use of wave equation analysis and dynamic pile tests, the recommended factor of safety is 2.25. We will be pleased to discuss wave equation analysis and dynamic pile testing with you and our experience with using these pile analysis and testing tools on similar projects. When installing the piling, if the penetration resistance to driving does not meet the required value after driving to a pile toe elevation of 5 feet below the anticipated depth needed to develop the design-working load, we recommend driving be halted and that the capacity be evaluated on restrike after allowing for soil set-up to occur. If the pile tip is driven past the estimated lengths shown in Tables 1 and 2, it is probable the piles have been overdriven and, after soil setup occurs, the pile working loads could be higher than necessary. D.3. Production Pile Observations All pile installed for the project should be driven in the presence of an experienced engineering assistant. The qualified personnel should document pertinent pile information such as pile length, elevations and driving resistances. This person should also document that the recommended driving/length criteria have been achieved for the piles. RVC Homes Project BABX-01-0124 April 12, 2001 Page 9 After the piles have been driven to adequate bearing and cut-off at design elevations, the inside of each pipe should be inspected to evaluate any damage and also to document the plumbness of the pile. Should the piles be damaged during driving,or should they be driven at an angle outside the plumbness specification,their load bearing capacities should be reviewed by the geotechnical engineer and the structural engineer. Contingencies should be included in the project budget for additional piles and additional pile length below the estimated"tip elevations. If the piles are not damaged during driving, and the piles have been driven within the plumbness specifications, they should then be filled with concrete. D.4. Backfills Fill should be placed in lifts not exceeding 4 to 12 inches in thickness, depending upon the material and size of the compactor used. Below slabs and pavement each lift should be compacted to a minimum of 95 percent of its standard Proctor maximum dry density. Other backfill can be compacted to a minimum of 90 percent of its standard Proctor maximum dry density. D.S. Backfill Compaction Testing We recommend density tests of backfills and fills placed beneath slabs and pavements. Samples of proposed backfill and fill materials should be submitted to our testing laboratory at least three days prior to placement for evaluation of their suitability and determination of their optimum moisture contents and maximum dry densities. D.5.a. Floor Subgrade. If floor coverings or coatings less permeable than the concrete slab will be used, or if moisture is a concern, we recommend a vapor retarder be placed beneath the slab. (Some coverings, coatings or situations may require a vapor barrier, i.e., a membrane with a permeance less than 0.3 perms.) Industry standards generally recommend burying the vapor retarder or barrier beneath a laver of sand to reduce curling and shrinkage of the concrete, but this practice risks trapping water between the slab and vapor retarder or barrier. We recommend the vapor retarder or barrier be placed directly below the slab, making sure care is taken to prevent damage during concrete placement. and quality concrete and placement practices are used for construction. D.5.b. Seepage Control. If water percolates down alongside the walls, it may enter the basement through shrinkage cracks in the concrete or masonry block. Collecting run-off 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. RVC Homes Project BABX-01-0124 April 12, 2001 Page 10 As a precaution against basement seepage,we recommend installing a perimeter foundation drain system. The system should 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 5 percent of the particles by weight passing a number 200 sieve. Where the sandy gravel or sand backfill extends outside the footprint of the building, it should be capped by a slab, pavement or 1 foot of clayey topsoil. D.5.c. Earth Pressure. Backfill against the basement wall should be compacted to a minimum of 90 percent of its standard Proctor maximum dry density. Beneath steps, slabs and pavements, it should be compacted to a minimum of 95 percent. The walls should be braced prior to backfilling. If imported sandy gravel or sand is used as backfill against the wall, a lateral earth pressure of 40 psf per foot of depth should be used to design the basement wall. If clayey soil is used as backfill against a synthetic wall drainage system, we recommend using a lateral earth pressure of 60 psf per foot of depth for designing the wall. We do not recommend clayey soils be used for wall backfill. D.6. Settlement Plate Monitoring We recommend two to three settlement plates be surveyed and periodically monitored to document settlement of areas where grade changes in excess of two feet will occur. We recommend the settlement data be reviewed by a geotechnical engineer and risk assessments of future settlement be made prior to completion of exterior features. D.7. Cold Weather If soil correction work 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 RVC Homes Project BABX-01-0124 April 12, 2001 Page 11 penetrate below footings bearing on frost-susceptible soil since such freezing could heave and crack the footings and/or foundation walls. E. Procedures E.1. Drilling and Sampling We performed the penetration test borings on March 23 and March 26, 2001, with a drill rig mounted on an off-road carrier, equipped with 3 1/4-inch inside diameter hollow-stem auger. Sampling for the borings was conducted in general accordance with ASTM D 1586, "Penetration Test and Split-Barrel Sampling of Soils." We advanced the boreholes with the hollow-stem auger to the desired test depths. A 140-pound 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. Samples were taken at 2 1/2-foot vertical intervals to the 20 and 40-foot depths and then at 5-foot intervals to the termination depths of the borings. A representative portion of each sample was then sealed in a glass jar capped with a lid. E.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 60 days to be available for your examination. E.3. Groundwater Observations Immediately after taking the final samples in the bottoms of the borings, our drill crew probed the holes through the hollow-stem auger to check for the presence of groundwater. Immediately after withdrawal of the auger, the holes were again probed and the depths to water or cave-ins were noted. The borings were then immediately backfilled with quickset grout. F. General Recommendations F.1. Basis of Recommendations The 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 RVC Homes Project BABX-01-0124 April 12, 2001 Page 12 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 or foundation 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 phase 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. F.2. Review of Design This report is based on the design of the proposed house 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. F.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. F.4. Use of Report This report is for the exclusive use of RVC Homes to use to design the proposed house 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. RVC Homes Project BABX-01-0124 April 12, 2001 Page 13 F.5. Level of Care Services performed by Braun Intertec Corporation personnel for this project have been conducted with that level of care and skill ordinarily exercised by members of the profession currently practicing in this area under similar budget and time restraints. No warranty, expressed or implied, is made. Professional Certification I hereby certify that this 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. 1,/241 egg R. dro Senior Principal Engineer Registration Number: 18221 April 10, 2001 • Appendix IV / . /111 A ,f• �L ;i:704- Iia:-: • S 89°07' 25" E 164 (93' i1 umw+OLE (93��2 '� iy�J:� Amommommilimma Jr 9 � 1 t GS N7ft " 4.• n 193'.4) ii 2.00 mALE 4:14"1" (;39.6) O .4-4- ..-. qo ' a '' u - 1 ST-2 � 342�t _ • • N r. . CO C). 3• ., .0, 0 _ . 94: 1--10'65.j:- -c 'ani'' Xs-, 7. ;•t• EE QtMcrEDI i� PROPOSED . o- I4.--- •0' - - - - - - � .....11. • • PR•::,SSE q HOUSErXII (357 . : _ - - - IN _lb 4" �Z. I�Riv_ltiA ,- _ i94 _ _ _��z_ - - . _ r - N ` . _ 1 C4ST-1 n _ - _ r---.515-,-' rCARA'v'C 2- �v Gl 4: - ( LI 41 f AAK.._ i..,\ . =`G' JET9,Ch 197 7 1 . ii475i (9.32) 54" W S 83°4 EXISTING I 1. NOL I ‘945.5‘ INT DATE SHEET BRAUN' Boring Location Sketch DRAWN BY: — I 1080 Wildhurst Trail APP'D BY: 6,,r4 OF1 INTERTECOrono, Minnesota ,GB No. BA8x•0,- 124 DWG.No. ! FIGURES I SCALE NO('E BRAUN" LOG OF BORING tNTERTEC Braun Project BABX-01-0124 BORING: ST-1 I GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Proposed Residence 1080 Wildhurst Trail Orono,Minnesota DRILLER: K.Keck METHOD: 3 1/4"HSA Autohammer DATE: 3/26/01 SCALE: 1"=4' 1 Elev. Depth feet feet ASTM Description of Materials BPF WL Tests or Notes 945.0 0.0 Symbol (ASTM D2488 or D2487) FILL p❖• FILL: Silty Sand,fine-to medium-grained,with Gravel, Benchmark: Lower sanitary •:•:. brown to black. _ manhole cover at 1074 943.0 2.0 :❖: Wildhurst Trail,elevation K Y equals 835.2. FILL •.•.• FILL: Lean Clay,with a trace of roots,brown,moist. 1 21 1 •; BRA w LOG OF BORING Ri' TERTEC Braun Project BABX-01-0124 BORING: ST-2 GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Proposed Residence 1080 Wildhurst Trail Orono,Minnesota DRILLER: K.Keck METHOD: K.Keck DATE: 3/23/01 SCALE: 1"=4' Elev. Depth feet feet ASTM Description of Materials BPF WL Tests or Notes 937.5 0.0 Symbol (ASTM D2488 or D2487) FILL ::•.• FILL: Lean Clay with Sand,mixed with topsoil,with a .❖.- trace of fibers,dark brown,moist. .;... ... iii A 2 ••••• 933.5 4.0 ••'•' ties FILL ❖:• FILL: Mixed Lean Clay with Sand and Silty Sand,with a .•••• trace of fibers,dark brown and brown,moist. 5 i— i BRAUN" LOG OF BORING 1 NTE BTEC Braun Project BABX-01-0124 BORING: ST-2 (cont.) GEOTECHNICAL EVALUATION LOCATION: See attached sketch. Proposed Residence 1080 Wildhurst Trail Orono,Minnesota DRILLER: K.Keck METHOD: K.Keck DATE: 3/23/01 SCALE: 1"=4' Elev. Depth feet feet ASTM Description of Materials BPF WL Tests or Notes 905.5 32.0 Symbol (ASTM D2488 or D2487) OH ,u Slightly ORGANIC CLAY. 'I 3 904.5 33.0 -.ANcontinued from previous page) SC CLAYEY SAND,fine-to medium-grained,with fine – Gravel,gray,wet,very loose. 902.5 35.0 (Glacial Till) u �� n 3 CL % LEAN CLAY,dark gray,wet,soft to rather soft. – � (Glacial Till) – — 899.0 38.5 I� X 5 °_ SC CLAYEY SAND,with a trace of fine Gravel,gray,wet, _ loose. 1— % (Glacial Till) �( 5 a 0 co – — /f a C. 892.5 45.0 �. jam 9 ; • IJ1G;JVI ?OILS Vii 1111 IIINS IV111.0&✓ (11° Standard D 2487 - 93 Particle Size Identification Classification of Soils for Engineering Purposes (Unified Soil Classification System) Boulders over 12" Cobbles 3"to 12" Gravel Coarse 3/4"to 3" Criteria for Assigning Group Symbols and It SoilClassification• Fine No. 4 to 3/4" Group Names Using Laboratory tests' I Group Sand Symbol Group Name>_ Coarse No. 4 to No. 10 Gravels Clean Gravels C >4 and 1<C <3` g No. 10 to No. 40 � C. GW Wes-graded rave' Medium y a More mm an 50%of Less an 5%fines` C <4 ane/or 1>C.>3' GP Poorly graded grave' Fine No. 40 to No. 200 I: a > ..swat . coarse Silt No. 200 to .005 mm o - d retained on Gravels with Fines Fines assay as ML a MH GM Silty travel.'" ze ;a a a N m12%No.4 sieve More an fines` Fines classily as Cl or CH GC Clayey graver" Clay less than .005 mm ci 3 o Sands Clean Sands I C,>6 and 1<C.<3• SW Well-graded sand• Z SO%or more of Less than 5%mss' C <6 and/or 1>C,>1' SP Peony grades sane' Relative Density of C.1 c coarse fraction Passes Sands with Fines Fates classify as Mt or MH -i SM SiW sane"''' Cohesionless Soils No.4 sieve More than 12%Ones' Fines tdassdy as Cl.or CH (SC Clayey sand•" P1>7 and mots on or aoove'A'line. CL lean clay Lir. very Loose 0 to 4 BPF f Silts and Clays2 inorganic I loose 5 to 10 BPF Z-0 PI<4 or[Nott below'A"line•• ML Sill''" O rot N �l burdlimd I �� medium dense 11 to 30 BPF e e^i lass lean SO organic Cleoid limo•oven fined <0.75 OL Organic clay dense c a S I 1 Liquid tuna.nw driers orgasm as 31 to SO BPF B• g very dense over 50 BPF - c I PI plots on or above"A'lute CH Fat ciav-"' a 'o Z 1 Silts and Clays inorganic ^ PI pael pats botnr'A"line MH Elastic sra Liquid lime Consistency of Cohesive Soils '`s 50 or more I Liquid lima•oven dried <0.75 OH Organic clay'"'a organic Licata limn-not anew Organic sw`'"' very soft 0 to 1 BPF HiohN Organic Soils IPrimanly organic matter.clam in color.and arcane door I PT 'Peat soft 2 to 3 BPF > eased on Me material passing me 3-inor t75nenl some. rather soft 4 to 5 BPF b. it nerd sannore contained cowmen or mtades,or born.300-.nth comes or powders_or mm.-to gram name. medium 6 to 8 BPF Graves Mem 5 to 12%runes require mai symport: GW-GM we*oraded grave with sirs rather stiff 9 to 12 BPF Gw.GC wee-graders gave mien clay stiff 13 to 16 BPF GP-GM peony grease gave wan sae GP-GC peony,graders graee„ewn day very stiff 17 to 30 SPF ,l. Santo yap,5 to 12%fines rectums ares sweats: hard sw-sM wedQaaed sena Mem sit over 30 SPF SW-SC weraded sand war day SP-SM peony graced dared wenee s . Drilling Notes SP.SC dowry graded sand Mem may <. C,-0,./13. C.-(11,e Standard penetration test borings were advanced by o...0„ 3 1/4-or 6 1/4" 10 hollow-stern augers unless noted I. if sod cancan>15%sane.aaa"wen sand-to aouo name. I. u ones crassly as a ML use stmt synod GGG a or 5C-3M. otherwise. Jetting water was used to clean out auger prior to R e fines are waist add"vino organic fines'to grow name. sampling only where indicated on logs. Standard penetration ,. It sod conams>15%graver.add'war grater toqeorso name, test borings are desionated by the prefix -Si"(Split Tube). I. if Aaeoerg lima pmt in named area.sdi is a Ct-ML stay tray. t. It sad comatrts 15 co 29%pas No.200.an:'Mee sand"or-Mee grave.'..ncrever is oreaomnam. Power auger borings were advanced by 4" or 6"diameter. d > i. It socontains 30%pea No.200.preaonrrreeny sena.add'sanely-to goon name. m. Ir soil contains>30%pros No.200.prearnunarety graver.and"gravely-to gado name. COntinuous.f ioht. solid-stern augers. Soil classifications anC s. a>4 aro prod on or armee-A-sur. strata depths were inferred from disturbed samcies augered tc e Pt<4 or aces avow"A line. the surface and are. therefore. somewhat approximate. °' °I prom on o.amnia A Lie. Power auger bonnos are designated by the prefix "B". u. Pi plots brow'A'line. fid Hand auger borings were advanced manually with a 1 1/2" Far dasufisadoe of fine—grained ,J� diameter auger and were limited to the depth from which tr.e soda dna fine-grained freeman d /I auger could be manually withdrawn. Hand auger borings are 50.. rears•soils. indicated by the prefix -H" Fo.neon a"A";fie. C Menrt.r at Pi -25.5. 'J/ OSA ,t\°- Sampling: All samples were taken with the standard 2"CC x 40—men°'-d.r3na2ot ,/ split-tube sampler. except where noted. TIN ir.c;cafes thin- s 0, rm,eO d.�_ Chelm / cQ, wailed (undisturbed) tube sample. dance.atu.:atoA"; / 30—men'"-O9a181 BPF: Numbers indicate blows per foot retorted in stanCarc >' penetration test. also known as N" value. The sampler Was / se! 6•' into undisturbed soil below the hcitow-star..auger 4 30_ d• Driving resistances were then counted for second 3nc!arc 1 G%. MH ar OH I increments and added to get BPF. `F/here they :'reared C' I I significantly. they are reported in the following torr::. 2: .2 'c t0" /t I I the second Ana lhlra 5" increments s ML or CIL •2.JeC::Ve". 0 ) II WH: WH indicates the sampler ce^e:rel:ed so ,;rider .ve.c-. 0 10 16 ZD 30 40 50 50 TO 30 10 :co t0 of hammer and roes alone: anvtr.c not require= Liquid Limit (LL) WR: WR indicates the sampler penetrated sed .inder we:c_r: of rods alone: hammer we.gnt ane cr ivrrg not 'e_uued Laboratory Tests Note: All tests were run in general accoraar.ce ::rth DD Dry density, pcf OC Organic content. 95 Aopucaole ASTM standares. \ND- Wet density. pct S Percent of saturation. :5 MC Natural moisture content. o SG Specific gravity LI Liquid limit. '.S C Conesion. psi B R U N' F! Plastic limit. % 0 Angie of internal friction ?I Plasticity index. 'S du Unconfined compressive_:renatn, psi I NTE E RT E C F=00 casstnd 200 sieve op Pocxet cenetrometer etrent^t. sr Fe 1