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HomeMy WebLinkAboutJEROME STREET STATION - PDP210009 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTPRELIMINARY GEOTECHNICAL SUBSURFACE EXPLORATION REPORT BLOCK 1 – OLD TOWN NORTH FORT COLLINS, COLORADO SOILOGIC # 17-1079 April 10, 2017 Soilogic, Inc. 3050 67th Avenue, Suite 200  Greeley, CO 80634  (970) 535-6144 P.O. Box 1121  Hayden, CO 81639  (970) 276-2087 April 10, 2017 Brinkman Partners 3528 Precision Drive, Suite 100 Fort Collins, Colorado 80528 Attn: Ms. Tina Hippeli Re: Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic Project # 17-1079 Ms. Hippeli: Soilogic, Inc. (Soilogic) personnel have completed the preliminary geotechnical subsurface exploration you requested for an approximate 4-acre parcel of land described as Block 1 of the Old Town North subdivision in Fort Collins, Colorado The results of our preliminary exploration are included with this report. The subsurface materials encountered in the completed test borings consisted of a thin mantle of vegetation and topsoil underlain by light to dark brown silty lean clay/silty sand. The lean clay/silty sand varied from medium stiff to hard in terms of consistency or from loose to medium dense in terms of relative density, exhibited low swell potential at in-situ moisture and density conditions and extended to depths ranging from approximately 6 to 7 feet below ground surface, where it transitioned to relatively clean, brown sand and gravel. The sand and gravel varied from medium dense to very dense in terms of relative density, would be expected to be non-expansive based on the material’s physical properties and engineering characteristics and extended to the bottom of boring B-4 at a depth of approximately 15 feet below ground surface or to depths ranging from approximately 17 to 22 feet below grade at the location of borings B-1 through B-3, where it was underlain by blue-grey siltstone/sandstone bedrock. The siltstone/sandstone was very hard in terms of relative hardness, would be expected to be non-expansive or possess low swell potential at in-situ conditions based on the materials physical properties and engineering characteristics and extended to the bottom of borings B-1 through B-3 at a depth of approximately 30 feet below present site grades. Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 2 Groundwater was encountered in each of the completed site borings at depths ranging from approximately 7½ to 8 feet below ground surface at the time of drilling. When checked about 24 hours after completion of drilling, groundwater was measured at depths of approximately 6½, 7, 7 and 6½ feet below ground surface at the location of borings B- 1 through B-4 respectively. Groundwater level information is indicated in the upper right-hand corner of the attached boring logs. Based on the subsurface conditions encountered in the completed site borings, results of laboratory testing and type of construction proposed, we expect lightly-loaded residential structures could be constructed with conventional footing foundations and floor slabs bearing on the site lean clay/silty sand or sand and gravel with no to low swell potential. Care will be needed to ensure all individual structure footing foundations bear on like materials. Extending garage and any other upper-level footing foundations to bear at slightly greater depth may be required in some areas in order to develop consistent foundation bearing. Care will be needed to maintain adequate separation distances between footing foundations and the observed level of groundwater. Typically we recommend foundation excavations be established a minimum of three (3) feet above the observed groundwater level. This will require that foundation excavations extend no deeper than approximately 3½ to 4 feet below ground surface at the boring locations. As a result, raised basement or crawl space construction could be considered for this project site. Raising site grades through fill placement and/or lowering site groundwater levels with an underdrain could also be considered to facilitate full basement construction. An underdrain system would require a suitable outfall. The silty lean clay and silty sand soils encountered near surface in the completed site borings would be particularly susceptible to disturbance from construction activities when elevated in moisture content. In addition, the lean clay/silty sand would be expected to be soft/loose and elevated in moisture near current groundwater levels. Care should be taken to avoid disturbing the site soils and the need for corrective action. Cuts extended close to current groundwater levels may require construction of a working platform with filter fabric and screened rock to reduce disturbance to the subgrade soils Disturbed soils should be removed and replaced or reworked in place prior to placement of any fill or overlying Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 2 improvements. In addition, if soft/loose lean clay/silty sand are observed at proposed foundation bearing elevation at the time of construction of the proposed site structures, some overexcavation/backfill procedures or other approved stabilization measures may be required to redevelop suitable strength foundation bearing prior to concrete placement. Based on the results of completed laboratory testing, the site lean clay, silty sand and underlying sand and gravel appear suitable for use as low volume change (LVC) fill to develop the site. If city streets will be constructed as part of this project, a final pavement exploration will be required for the development after streets have been graded to approximate finish subgrade elevation and water and sewer utilities installed in accordance with the Larimer County Urban Area Street Standards (LCUASS). Other preliminary opinions and recommendations concerning design criteria and construction details for the proposed site improvements are included with this report. Preliminary pavement section design estimates are also included. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning the enclosed information or if we can be of further service to you in any way, please do not hesitate to contact us. Very Truly Yours, Soilogic, Inc. Reviewed by: Wolf von Carlowitz, P.E. Darrel DiCarlo, P.E. Principal Engineer Senior Project Engineer 36746 44271 PRELIMINARY GEOTECHNICAL SUBSURFACE EXPLORATION REPORT BLOCK 1 – OLD TOWN NORTH FORT COLLINS, COLORADO SOILOGIC # 17-1079 April 10, 2017 INTRODUCTION This report contains the results of the preliminary geotechnical subsurface exploration completed for an approximate 4-acre parcel of land described as Block 1 of the Old Town North subdivision in Fort Collins, Colorado. The purpose of our exploration was to describe the subsurface conditions encountered in the completed site borings and develop preliminary recommendations concerning design and construction of office and residence foundations and support of floor slabs and site pavements. Recommendations concerning the installation of site utilities and preliminary pavement section design estimates are also included. The conclusions and recommendations outlined in this report are based on the results of the completed field and laboratory testing and our experience with subsurface conditions in this area. PROPOSED CONSTRUCTION The proposed development includes a total of approximately 4 acres that may be developed with office buildings and residential structures. We expect the office structures will be lightly-loaded single-story steel structures constructed as slab-on-grade. The residences are expected to be one or two-story wood frame structures constructed over garden-level or raised basements due to the presence of comparatively shallow groundwater. Foundations loads for the structures are expected to be light, with continuous wall loads less than 3.5 kips per lineal foot and individual column loads less than 75 kips. Floor loads are expected to be light, less than 100 psf. Infrastructure improvements for the development will include utility installation and roadway construction. We expect the site roadways will be used by low volumes of passenger vehicles and light trucks, with occasional heavy truck traffic. Small grade changes are anticipated to develop finish site grades. Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 2 SITE DESCRIPTION The development site includes a total of approximately 4 acres described as Block 1 of the Old Town North subdivision in Fort Collins, Colorado. At the time of our site exploration, a large soil stockpile was observed to be generally centrally located on the project site. Outside of the soil stockpile, the site contained a moderate growth of grass and weed vegetation including a few small diameter deciduous trees and was relatively level, with the maximum difference in ground surface elevation across the property estimated to be less than 5 feet. Evidence of prior building construction was not observed in the area of proposed development at the time of drilling. SITE EXPLORATION Field Exploration To develop subsurface information across the development parcel, a total of four (4) soil borings were extended to depths ranging from approximately 15 to 30 feet below present site grades. The proposed boring locations were established in the field by Soilogic personnel based on a proposed boring layout diagram provided by the client and by pacing and estimating angels and distances from identifiable site references. A diagram indicating the approximate boring locations is included with this report. The boring locations outlined on the attached diagram should be considered accurate only to the degree implied by the methods used to make the field measurements. Graphic logs of each of the auger borings are also included. The test holes were advanced using 4-inch diameter continuous-flight auger powered by a truck-mounted CME-45 drill rig. Samples of the subsurface materials were obtained at regular intervals using California barrel sampling procedures in general accordance with ASTM specification D-1586. As part of the D-1586 sampling procedure, the standard sampling barrel is driven into the substrata using a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the sampler a distance of 12 inches is recorded and helpful in estimating the consistency, relative density and/or hardness of the soils and/or bedrock encountered. In the California barrel sampling procedure, lesser disturbed samples are obtained in removable brass liners. Samples of Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 3 the subsurface materials obtained in the field were sealed and returned to the laboratory for further evaluation, classification and testing. As part of our field services, slotted PVC piezometers were installed in the open boreholes prior to backfilling to allow for longer-term observation of site groundwater levels. Laboratory Testing The samples collected were tested in the laboratory to measure natural moisture content and visually and/or manually classified in accordance with the Unified Soil Classification System (USCS). The USCS group symbols are indicated on the attached boring logs. An outline of the USCS classification system is included with this report. Classification of bedrock was completed through visual and tactual observation of disturbed samples. Other bedrock types could be revealed through petrographic analysis. As part of the laboratory testing, a calibrated hand penetrometer (CHP) was used to estimate the unconfined compressive strength of essentially-cohesive specimens. The CHP also provides a more reliable estimate of soil/bedrock consistency than tactual observation alone. Dry density, Atterberg limits, -200 wash and swell/consolidation tests were completed on selected samples to help establish specific soil/bedrock characteristics. Atterberg limits tests are used to determine soil/bedrock plasticity. The percent passing the #200 size sieve (-200 wash) test is used to determine the percentage of fine-grained materials (clay and silt) in a sample. Swell/consolidation tests are performed to evaluate soil/bedrock volume change potential with variation in moisture content. The results of the completed laboratory tests are outlined on the attached boring logs and swell/consolidation test summaries. Water Soluble Sulfates (WSS) tests were also completed on two (2) selected soil samples to evaluate corrosive soil characteristics with respect to buried concrete and results discussed subsequently in this report. SUBSURFACE CONDITIONS The subsurface materials encountered in the completed test borings consisted of a thin mantle of vegetation and topsoil underlain by light to dark brown silty lean clay/silty sand. The apparently natural lean clay/silty sand varied from medium stiff to hard in terms of consistency or from loose to medium dense in terms of relative density, Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 4 exhibited low swell potential at in-situ moisture and density conditions and extended to depths ranging from approximately 6 to 7 feet below ground surface, where it transitioned to relatively clean, brown sand and gravel. The sand and gravel varied from medium dense to very dense in terms of relative density, would be expected to be non- expansive based on the material’s physical properties and engineering characteristics and extended to the bottom of boring B-4 at a depth of approximately 15 feet below ground surface or to depths ranging from approximately 17 to 22 feet below grade at the locations of borings B-1 through B-3, where it was underlain by grey/blue siltstone/sandstone bedrock. The siltstone/sandstone was very hard in terms of relative hardness, would be expected to be non-expansive or possess low swell potential at in-situ conditions based on the materials physical properties and engineering characteristics and extended to the bottom of borings B-1 through B-3 at a depth of approximately 30 feet below present site grades. The stratigraphy indicated on the included boring logs represents the approximate location of changes in soil and bedrock types. Actual changes may be more gradual than those indicated. Groundwater was encountered in each of the completed site borings at depths ranging from approximately 7½ to 8 feet below ground surface at the time of drilling. When checked about 24 hours after completion of drilling, groundwater was measured at depths of approximately 6½, 7, 7 and 6½ feet below ground surface at the location of borings B- 1 through B-4 respectively. Groundwater level information is indicated in the upper right-hand corner of the attached boring logs. Groundwater levels will vary seasonally and over time based on weather conditions, site development, irrigation practices and other hydrologic conditions. Perched and/or trapped groundwater conditions may also be encountered at times throughout the year. Perched water is commonly encountered in soils overlying less permeable soil layers and/or bedrock. Trapped water is typically encountered within more permeable zones of layered soil and bedrock systems. The location and amount of perched/trapped water can also vary over time. Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 5 ANALYSIS AND RECOMMENDATIONS General Groundwater was measured in the installed site piezometers at depths ranging from approximately 6½ to 7 feet below ground surface when checked about 24 hours after the completion of drilling. Typically, we recommend foundation bearing be established a minimum of three (3) feet above the level of water observed in order to account for some seasonal fluctuation in the level of water and reduce the potential for water infiltration into basement areas of the proposed residences. This will result in maximum foundation excavation depths in the range of about 3½ to 4 feet below grade. As such, raised basement or crawl space construction could be considered for this site. Closer evaluation of the depth to groundwater should be completed during site-specific explorations, to be performed after site development in order to better define the depth to groundwater at the individual structure locations. Raising site grades through fill placement or lowering site groundwater levels with an underdrain system could be considered to facilitate full basement construction. An underdrain system would require a suitable outfall. Care will be needed to ensure all individual structure footing foundations bear on like materials. Extending garage and any other upper-level footing foundations to bear at slightly greater depth may be required in some areas in order to develop consistent foundation bearing. The silty lean clay and silty sand soils encountered near surface in the completed site borings would be particularly susceptible to disturbance from construction activities when elevated in moisture content. In addition, the lean clay/silty sand would be expected to be soft/loose and elevated in moisture near current groundwater levels. Care should be taken to avoid disturbing the site soils and the need for corrective action. Cuts extended close to current groundwater levels may require construction of a working platform with filter fabric and screened rock to reduce disturbance to the subgrade soils Disturbed soils should be removed and replaced or reworked in place prior to placement of any fill or overlying improvements. In addition, if soft/loose lean clay/silty sand are observed at proposed foundation bearing elevation at the time of construction of the proposed site structures, Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 6 some overexcavation/backfill procedures or other approved stabilization measures may be required to redevelop suitable strength foundation bearing prior to concrete placement. Site Development All existing vegetation and topsoil should be completely removed from any proposed fill and exterior flatwork and pavement areas. We do not expect the stockpiled site soils were placed as controlled and compacted fill and tested at the time of placement and compaction for moisture and density, such that all existing stockpiled fill should also be completely removed at this time. After stripping and completing all fill removal and any cuts and prior to placement of any new fill or flatwork concrete, we recommend the exposed subgrade soils be scarified to a depth of 9 inches, adjusted in moisture content and compacted to at least 95% of the materials standard Proctor maximum dry density. The moisture content of the scarified soils should be adjusted to be within the range of ±2% of standard Proctor optimum moisture content at the time of compaction. Fill soils required to develop the site should consist of approved, low-volume-change (LVC) soils free from organic matter, debris and other objectionable materials. Based on results of the completed laboratory testing, it is our opinion the site lean clay, silty sand and underlying sand and gravel could be used as fill to develop the site provided the proper moisture content is developed in those materials at the time of placement and compaction. Further evaluation of the stockpiled site soils would be required to determine if these materials would be suitable for use as fill to develop the site. Suitable fill soils should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted as recommended for the scarified soils above. Care should be taken to avoid disturbing the reconditioned subgrade soils and placed fill soils. Soils which are allowed to dry out or become wet and softened or disturbed by the construction activities should be removed and replaced or reworked in place prior to placement of any overlying improvements. Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 7 Footing Foundations Based on the materials encountered in the completed site borings and the results of laboratory testing, we expect a majority, if not all of the relatively lightly-loaded site structures could be supported on conventional footing foundations bearing on the natural, undisturbed site lean clay, silty sand and/or sand and gravel with low swell potential and/or suitable fill soils placed and compacted as outlined above a minimum of three (3) feet above observed groundwater. The foundations for the individual structures should bear on like materials. Drilled pier foundations could also be considered for support of more heavily loaded site structures, but will most likely require casing of the drilled shafts to facilitate construction as well as specialized rock augers/core barrels to fully penetrate the very hard bedrock encountered. For design of footing foundations bearing on the natural site lean clay, silty sand and/or properly placed and compacted fill, maximum net allowable soil bearing pressures in the range of 1,000 to 2,000 psf appear usable. Overexcavation and replacement of the proposed foundation bearing soils with select granular import fill could also be considered to develop higher maximum net allowable soil bearing pressures (in the range of 2,000 to 3,000 psf). Individual site-specific subsurface explorations should be completed for each proposed site structure after overlot grading of the site has been completed to help better define subsurface soil/bedrock and groundwater conditions. Floor Slabs Based on the results of the completed laboratory testing, we expect a majority of lightly- loaded floor slabs could be supported on reconditioned natural site soils and/or properly placed and compacted fill. If moderately expansive clay soils or existing undocumented fill are identified near surface, some overexcavation/backfill procedures would be required beneath garage and any other at-grade floor slabs prior to concrete placement. Care should be taken to avoid disturbing floor slab subgrades prior to concrete placement. Subgrade soils expected to receive flatwork concrete should be evaluated closely prior to surfacing. If areas of disturbed, wet and softened, or dry subgrade soils develop during Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 8 construction, those materials should be removed and replaced or reworked in place prior to placement of the overlying improvements. Raised Basement/Crawl Space Construction We recommend perimeter drain systems be installed around all below-grade and crawl space areas to help reduce the potential for development of hydrostatic pressures behind the foundation walls and water infiltration into the basement/crawl space areas. A perimeter drain system should consist of a 4-inch diameter perforated drain pipe surrounded by a minimum of six (6) inches of free-draining gravel. A filter fabric should be considered around the free-draining gravel or perforated pipe to reduce the potential for an influx of fine-grained soils into the system. The drain pipe should be placed at approximate foundation bearing level around the exterior perimeter of the below-grade areas and interior perimeter of crawl space areas and run to a sump pit and pump system, or project underdrain system with a minimum slope of ⅛-inch per foot to facilitate efficient water removal. Backfill placed adjacent to the foundation walls should consist of LVC potential and relatively impervious soils which are free from organic matter, debris and other objectionable materials. The site lean clay and silty sand could be used as fill in these areas. Foundation wall backfill soils should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture and compacted as previously outlined in the “Site Development” section of this report. Excessive lateral stress can be imposed on below-grade walls when using heavier mechanical compaction equipment. We recommend compaction of unbalanced basement wall backfill be completed using light mechanical or hand compaction equipment. Utility Installation Bedding around utility pipelines should be placed in accordance with recommendations from the pipeline designer. Backfill soils placed above pipelines should consist of approved materials which are free from organic matter, debris and other objectionable materials. The on-site lean clay, silty sand and underlying sand and gravel could be used Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 9 as pipeline backfill. Pipeline backfill should be placed in maximum 9-inch loose lifts, adjusted in moisture and compacted as previously outlined in the “Site Development” section of this report. Wet soils encountered with depth would need to be dried out prior to placement as utility backfill. The site silty sand and cleaner sand and gravel soils encountered with depth in the completed site borings would be particularly susceptible to sloughing and caving during excavation. Care will be needed to ensure utilities are not placed on or above disturbed or sloughed materials. Utility excavations will likely expose the overburden lean clay, silty sand and cleaner sand and gravel with depth. Care will also be needed to develop stable side slopes in pipeline trenches excavated through soft lean clay and less cohesive silty sand and gravel soils. As such, we expect temporary shoring, bracing, or cutting of shallow slopes may be necessary in deeper excavations. Excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. As a safety measure, it is recommended that vehicles and soil stockpiles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. Cuts below groundwater elevation will require dewatering to facilitate proper construction. We expect a majority of the dewatering procedures could be completed through open pumping procedures in sumps fed from ditches or sloped trench excavations. Deeper utility excavations may require well point systems for dewatering in order to facilitate proper construction. Site Roadways We expect the pavement subgrades will consist of the site lean clay and silty sand with low swell potential. If City of Fort Collins streets with be constructed as part of this project, a final subgrade evaluation and pavement section design report will be required once roadways are developed to approximate finish grade and water and sewer utilities installed in accordance with the Larimer County Urban Area Street Standards (LCUASS). For preliminary design estimates, a pavement section consisting of 4 inches of asphaltic concrete overlying 6 inches of aggregate base course could be used for local residential streets and light duty private pavement areas. A pavement section consisting Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 10 of 5 inches of asphaltic concrete overlying 8 inches of aggregate base course could be used for preliminary estimates for collector roadways and heavy-duty private pavement areas. Drainage Positive drainage is imperative for satisfactory long-term performance of the proposed site structures and associated site improvements. We recommend positive drainage be developed away from all site structures and pavement areas to reduce the potential for wetting of the subgrade and bearing materials. Water which is allowed to pond adjacent to the site improvements can result in unacceptable performance of those improvements over time. LIMITATIONS This report was prepared based upon the data obtained from the completed site exploration, laboratory testing, engineering analysis and any other information discussed. The completed borings provide an indication of subsurface conditions at the boring locations only. Variations in subsurface conditions can occur in relatively short distances away from the borings. This report does not reflect any variations which may occur across the site or away from the borings. If variations in the subsurface conditions anticipated become evident, the geotechnical engineer should be notified immediately so that further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any biological or environmental assessment of the site or identification or prevention of pollutants or hazardous materials or conditions. Other studies should be completed if concerns over the potential of such contamination or pollution exist. The geotechnical engineer should be retained to review the plans and specifications so that comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. The geotechnical engineer should also be retained to provide testing and observation services during construction to help determine that the design requirements are fulfilled. Preliminary Geotechnical Subsurface Exploration Report Block 1 – Old Town North Fort Collins, Colorado Soilogic # 17-1079 11 This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with the generally accepted standard of care for the profession. No warranties express or implied, are made. The conclusions and recommendations contained in this report should not be considered valid in the event that any changes in the nature, design or location of the project as outlined in this report are planned, unless those changes are reviewed and the conclusions of this report modified and verified in writing by the geotechnical engineer. LOG OF BORING B-1 1/1 CME 45 4" CFA Automatic CP/ZG Estimated Swell % Passing SOIL DESCRIPTION Depth "N"MC DD qu % Swell @ Pressure # 200 Sieve (ft)(%)(pcf)(psf)500 psf (psf)LL PI (%) 6" VEGETATION AND TOPSOIL - 1 - 2 CL-SM SILTY LEAN CLAY/SILTY SAND - light to dark brown 3 very stiff/medium dense - 4 - 5 CS 23 7.2 -N/A ----- - 6 - 7 - 8 - 9 SP-GP SAND AND GRAVEL - brown 10 CS 19 4.1 -N/A --NL NP 5.4% medium dense to dense - 11 - 12 - 13 - 14 - 15 CS 50/10 6.0 -N/A ----- - 16 - 17 - 18 - 19 - 20 CS 50/4 17.9 -9000+----- - 21 - SILTSTONE/SANDSTONE 22 grey/blue - very hard 23 - 24 - 25 - 26 - 27 - 28 - 29 - BOTTOM OF BORING @ 30.0'30 CS 50/2 --- - - - - - USCSSamplerAtterberg Limits Surface Elev.-Field Personnel:24 Hours After Drilling 6.5' Finish Date 3/23/2017 Hammer Type:After Drilling 8' Sheet Drilling Rig:Water Depth Information Start Date 3/23/2017 Auger Type:During Drilling 8' BLOCK 1 - OLD TOWN NORTH PRELIMINARY EXPLORATION FORT COLLINS, COLORADO Project # 17-1079 April 2017 LOG OF BORING B-2 1/1 CME 45 4" CFA Automatic CP/ZG Estimated Swell % Passing SOIL DESCRIPTION Depth "N"MC DD qu % Swell @ Pressure # 200 Sieve (ft)(%)(pcf)(psf)500 psf (psf)LL PI (%) 6" VEGETATION AND TOPSOIL - 1 - 2 CL-SM SILTY LEAN CLAY/SILTY SAND - light to dark brown 3 stiff - 4 - 5 CS 12 2.7 -N/A --NL NP 13.9% - 6 - 7 - 8 - 9 - SP-GP SAND AND GRAVEL 10 CS 29 5.0 -N/A ----- brown - medium dense to very dense 11 - 12 - 13 - 14 - 15 CS 50/8 8.5 -N/A ----- - 16 - 17 - 18 - 19 - 20 CS 50/7 16.3 -N/A ----- - 21 - 22 - 23 - SILTSTONE/SANDSTONE 24 grey/blue - very hard 25 - 26 - 27 - 28 - 29 - BOTTOM OF BORING @ 30.0'30 CS 50/2 --- - - - - - Sheet Drilling Rig:Water Depth Information BLOCK 1 - OLD TOWN NORTH PRELIMINARY EXPLORATION FORT COLLINS, COLORADO Project # 17-1079 April 2017 USCSSamplerAtterberg Limits Start Date 3/23/2017 Auger Type:During Drilling 8' Finish Date 3/23/2017 Hammer Type:After Drilling 8' Surface Elev.-Field Personnel:24 Hours After Drilling 7' LOG OF BORING B-3 1/1 CME 45 4" CFA Automatic CP/ZG Estimated Swell % Passing SOIL DESCRIPTION Depth "N"MC DD qu % Swell @ Pressure # 200 Sieve (ft)(%)(pcf)(psf)500 psf (psf)LL PI (%) 6" VEGETATION AND TOPSOIL - 1 - 2 CL-SM SILTY LEAN CLAY/SILTY SAND - light to dark brown 3 hard/medium dense - 4 - 5 CS 41 15.9 -N/A ----- - 6 - 7 - 8 - SP-GP SAND AND GRAVEL 9 brown - medium dense to dense 10 CS 20 8.0 -N/A --NL NP 6.8% - 11 - 12 - 13 - 14 - 15 CS 50/8 7.8 -N/A ----- - 16 - 17 - 18 - 19 - SILTSTONE/SANDSTONE 20 CS 50/3 21.0 -9000+----- grey/blue - very hard 21 - 22 - 23 - 24 - 25 - 26 - 27 - 28 - 29 - BOTTOM OF BORING @ 30.0'30 CS 50/2 --- - - - - - Sheet Drilling Rig:Water Depth Information BLOCK 1 - OLD TOWN NORTH PRELIMINARY EXPLORATION FORT COLLINS, COLORADO Project # 17-1079 April 2017 USCSSamplerAtterberg Limits Start Date 3/23/2017 Auger Type:During Drilling 7.5' Finish Date 3/23/2017 Hammer Type:After Drilling 7.5' Surface Elev.-Field Personnel:24 Hours After Drilling 7' LOG OF BORING B-4 1/1 CME 45 4" CFA Automatic CP/ZG Estimated Swell % Passing SOIL DESCRIPTION Depth "N"MC DD qu % Swell @ Pressure # 200 Sieve (ft)(%)(pcf)(psf)500 psf (psf)LL PI (%) 6" VEGETATION AND TOPSOIL - 1 - 2 CL-SM SILTY LEAN CLAY/SILTY SAND - light to dark brown 3 medium stiff/loose - 4 - 5 CS 8 25.5 97.3 5000 0.2%600 --- - 6 - 7 - 8 - 9 SP-GP SAND AND GRAVEL - brown 10 CS 50/10 8.8 -N/A --NL NP 4.1% medium dense to dense - 11 - 12 - 13 - 14 - 15 CS 25 9.2 -N/A ----- BOTTOM OF BORING @ 15.0'- 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 Sheet Drilling Rig:Water Depth Information BLOCK 1 - OLD TOWN NORTH PRELIMINARY EXPLORATION FORT COLLINS, COLORADO Project # 17-1079 April 2017 USCSSamplerAtterberg Limits Start Date 3/23/2017 Auger Type:During Drilling 8' Finish Date 3/23/2017 Hammer Type:After Drilling 8' Surface Elev.-Field Personnel:24 Hours After Drilling 6.5' Liquid Limit - Plasticity Index - % Passing #200 - Dry Density (pcf)97.3 500 Final Moisture 26.0% % Swell @ 500 psf 0.2% Swell Pressure (psf)600 Sample ID: B-4 @ 4 Sample Description: Dark Brown Sandy Lean Clay (CL) Initial Moisture 25.5% SWELL/CONSOLIDATION TEST SUMMARY BLOCK 1 - OLD TOWN NORTH PRELIMINARY EXPLORATION FORT COLLINS, COLORADO Project # 17-1079 April 2017 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification Group Symbol Group NameB Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF Clean Gravels Less than 5% finesC Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravelF Fines classify as ML or MH GM Silty gravelF,G, H Coarse Grained Soils More than 50% retained on No. 200 sieve Gravels More than 50% of coarse fraction retained on No. 4 sieve Gravels with Fines More than 12% finesC Fines classify as CL or CH GC Clayey gravelF,G,H Cu ! 6 and 1 " Cc " 3E SW Well graded sandI Clean Sands Less than 5% finesD Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sandI Fines classify as ML or MH SM Silty sandG,H,I Sands 50% or more of coarse fraction passes No. 4 sieve Sands with Fines More than 12% finesD Fines classify as CL or CH SC Clayey sandG,H,I PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M Silts and Clays Liquid limit less than 50 Inorganic PI < 4 or plots below “A” lineJ ML SiltK,L,M Liquid limit - oven dried Organic clayK,L,M,N Fine-Grained Soils 50% or more passes the No. 200 sieve Organic Liquid limit - not dried < 0.75 OL Organic siltK,L,M,O Inorganic PI plots on or above “A” line CH Fat clayK,L,M Silts and Clays Liquid limit 50 or more PI plots below “A” line MH Elastic siltK,L,M Liquid limit - oven dried Organic clayK,L,M,P Organic Liquid limit - not dried < 0.75 OH Organic siltK,L,M,Q Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat A Based on the material passing the 3-in. (75-mm) sieve B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name. C Gravels with 5 to 12% fines require dual symbols: GW-GM well graded gravel with silt, GW-GC well graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay. D Sands with 5 to 12% fines require dual symbols: SW-SM well graded sand with silt, SW-SC well graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay E Cu = D60/D10 Cc = F If soil contains ! 15% sand, add “with sand” to group name. G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM. HIf fines are organic, add “with organic fines” to group name. I If soil contains ! 15% gravel, add “with gravel” to group name. J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add “with sand” or “with gravel,” whichever is predominant. L If soil 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 “A” line. O PI < 4 or plots below “A” line. P PI plots on or above “A” line. Q PI plots below “A” line. GENERAL NOTES DRILLING & SAMPLING SYMBOLS: SS: Split Spoon - 1⅜" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube – 2.5" O.D., unless otherwise noted PA: Power Auger RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger CS: California Barrel - 1.92" I.D., 2.5" O.D., unless otherwise noted RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”. For 2.5” O.D. California Barrel samplers (CB) the penetration value is reported as the number of blows required to advance the sampler 12 inches using a 140-pound hammer falling 30 inches, reported as “blows per inch,” and is not considered equivalent to the “Standard Penetration” or “N-value”. WATER LEVEL MEASUREMENT SYMBOLS: WL: Water Level WS: While Sampling WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency. FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK (CB) Blows/Ft. (SS) Blows/Ft. Consistency (CB) Blows/Ft. (SS) Blows/Ft. Relative Density (CB) Blows/Ft. (SS) Blows/Ft. Consistency < 3 0-2 Very Soft 0-5 < 3 Very Loose < 24 < 20 Weathered 3-5 3-4 Soft 6-14 4-9 Loose 24-35 20-29 Firm 6-10 5-8 Medium Stiff 15-46 10-29 Medium Dense 36-60 30-49 Medium Hard 11-18 9-15 Stiff 47-79 30-50 Dense 61-96 50-79 Hard 19-36 16-30 Very Stiff > 79 > 50 Very Dense > 96 > 79 Very Hard > 36 > 30 Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY Descriptive Terms of Other Constituents Percent of Dry Weight Major Component of Sample Particle Size Trace < 15 Boulders Over 12 in. (300mm) With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm) Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm) Sand Silt or Clay #4 to #200 sieve (4.75mm to 0.075mm) Passing #200 Sieve (0.075mm) RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION Descriptive Terms of Other Constituents Percent of Dry Weight Term Plasticity Index Trace With Modifiers < 5 5 – 12 > 12 Non-plastic Low Medium High 0 1-10 11-30 30+