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HomeMy WebLinkAboutMANHATTAN TOWNHOMES, SECOND FILING - PDP/FDP - FDP150021 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL EXPLORATION REPORT MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO SOILOGIC # 15-1090 April 28, 2015 Soilogic, Inc. 4350 State Highway 66  Longmont, CO 80504  (970) 535-6144 P.O. Box 1121  Hayden, CO 81639  (970) 276-2087 April 28, 2015 KSR, LLC 772 Whalers Way, Suite 200 Fort Collins, Colorado 80524 Attn: Mr. James C. Rawson Re: Geotechnical Subsurface Exploration Report Manhattan Townhomes (3836 Manhattan Avenue) Fort Collins, Colorado Soilogic Project # 15-1090 Mr. Rawson: Soilogic, Inc. (Soilogic) personnel have completed the geotechnical subsurface exploration you requested for the proposed Manhattan Townhomes to be constructed at 3836 Manhattan Avenue in Fort Collins, Colorado. The results of our subsurface exploration and pertinent geotechnical engineering recommendations are included with this report. In summary, the subsurface materials encountered in the completed site borings consisted of a thin layer of vegetation and topsoil underlain by reddish brown sandy lean clay with varying amounts of gravel and varying to silty/clayey sand in places. A portion of the near surface lean clay and silty/clayey sand appeared to be fill soils which may have been placed to develop finish site grades. The lean clay and silty/clayey sand varied from stiff to very stiff in terms of consistency or loose to medium dense in terms of relative density and exhibited no to low swell potential at current moisture and density conditions. The lean clay and silty/clayey sand extended to depths ranging from approximately 8 to 9½ feet below ground surface and was underlain by brown/grey claystone bedrock. The claystone varied from weathered to very hard in terms of hardness, exhibited low to moderate swell potential at in-situ moisture and density conditions and extended to the bottom of boring at depths ranging from approximately 15 to 30 feet below present site grades. Groundwater was encountered in several of the completed site borings at the time of drilling. When checked approximately 7 days after completion of drilling, groundwater was measured at depths of approximately 4, 5, 5, 3½, 5, 4, 4, 4, and 1 foot below ground Geotechnical Subsurface Exploration Report Manhattan Townhomes (3836 Manhattan Avenue) Fort Collins, Colorado Soilogic # 15-1090 2 surface at boring locations B-1 and B-3 through B-10 respectively. Boring B-2 was observed to be dry to a depth of approximately 14 feet below grade at that time. Up to approximately 4½ feet of probable existing fill material was encountered near- surface in a portion of the completed site borings. Based on provided site topography, the site appears to have been filled on the order of approximately 4 feet in some areas to develop finish grades. While the apparent fill soils were observed to be relatively consistent in terms of consistency and relative density and exhibited no to low swell potential at in-situ moisture and density conditions, we are unaware if this fill material was monitored and tested for moisture and density control at the time of placement and compaction and records of control during placement have not been provided. Unless documentation of the control of this fill can be provided to Soilogic for review prior to construction, the only way to be sure excessive movement of footing foundations and floor slabs will not occur subsequent to construction would be to completely remove any existing fill to natural underlying lean clay or silty/clayey sand level and backfill the removed materials replaced as low volume change (LVC), controlled and compacted, moisture-conditioned fill where applicable. Based on results of the completed laboratory testing, the existing site fill soils could be used as overexcavation/backfill provided the proper moisture content is developed in those materials at the time of placement and compaction. Extending footing foundations to bear on natural undisturbed soils could also be considered, but overexcavation/backfill procedures beneath floor slabs, exterior flatwork and site pavements would still be required. Some dewatering of foundation excavations extended to bear on natural site soils and/or during fill removal and replacement may be required. Due to the comparatively shallow groundwater levels observed in the completed site borings, we do not believe full basement construction is feasible. We recommend limiting finish first-floor slab elevations to at least three (3) feet above the level of water observed in order to account for some seasonal fluctuation in the level of groundwater and to reduce the potential for water infiltration in the crawl-space areas (if any), as well as to reduce the potential for soft/loose ground stabilization measures. In addition, we recommend footing foundations be established a minimum of three (3) feet above claystone bedrock level. Careful evaluation of the proposed foundation bearing materials should be completed at the time of construction to help ensure all individual structure footing Geotechnical Subsurface Exploration Report Manhattan Townhomes (3836 Manhattan Avenue) Fort Collins, Colorado Soilogic # 15-1090 3 foundations bear on like materials with suitable strength and low volume change potential. Other opinions and recommendations concerning design criteria and construction details for the proposed site improvements are included with this report. 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 GEOTECHNICAL SUBSURFACE EXPLORATION REPORT MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO SOILOGIC # 15-1090 April 28, 2015 INTRODUCTION This report contains the results of the completed geotechnical subsurface exploration for the proposed Manhattan Townhomes development to be constructed at 3836 Manhattan Avenue in Fort Collins, Colorado. The purpose of our exploration was to describe the subsurface conditions encountered in the completed site borings and develop the test data necessary to provide recommendations concerning design and construction of the multi- family residential and detached bank garage building foundations and support of floor slabs, exterior flatwork and site pavements. Pavement section design options for the site parking areas are also included. The conclusions and recommendations outlined in this report are based on results of the completed field and laboratory testing and our experience with subsurface conditions in this area. PROPOSED CONSTRUCTION Six (6) residential structures containing a total of 36 units are proposed for the project site, with plan areas of the buildings ranging from approximately 3,400 to 6,500 square feet. In addition, two (2) bank garage structures are also anticipated. We understand the townhome buildings will be lightly-loaded, 2 to 3-story wood-frame structures constructed as slab-on-grade or over crawl-spaces due to the presence of comparatively shallow groundwater. The detached bank garage structures are expected to be single- story wood-frame structures constructed as slab-on-grade. Foundations loads for the structures are expected to be relatively light, with continuous wall loads less than 3.5 kips per lineal foot and individual column loads less than 100 kips. Paved parking areas will be constructed adjacent to the residences as part of the proposed site improvements. Paved roadways are also anticipated and will be designed and constructed in accordance with the Larimer County Urban Area Street Standards (LCUASS) and provided under separate cover. Small grade changes are anticipated to develop finish site grades in the building and pavement areas. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 2 SITE DESCRIPTION The development property includes an approximate 2.2-acre parcel located at 3836 Manhattan Avenue in Fort Collins, Colorado. At the time of our site exploration, the lot was observed to be gently sloping to the east/southeast overall, with the maximum difference in ground surface elevation across the site estimated to be approximately six (6) feet based on provided site topography. Overlot grading of the site appeared to have been completed with locally developed building pads and areas of possible fills on the order of approximately 3 to 4 feet in height. A small depressed area was noted in the southeast corner of the property. SITE EXPLORATION Field Exploration To develop subsurface information for the proposed construction, a total of ten (10) soil borings were completed across the site in areas of proposed structures to depths between approximately 15 to 30 feet below present site grades. The boring locations were established in the field by Soilogic personnel based on a provided site plan and by pacing and estimating angles and distances from identifiable site references. The boring locations should be considered accurate only to the degree implied by the methods used to make the field measurements. A diagram indicating the approximate boring locations is included with this report. 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 Mobile B-50 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, standard sampling barrels are driven into the substrata using a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the samplers a distance of 12 inches is recorded and helpful in estimating the consistency, relative density or hardness of the soils and/or bedrock encountered. In the California barrel sampling procedure, lesser disturbed samples are obtained in removable brass Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 3 liners. Samples of the subsurface materials obtained in the field were sealed and returned to the laboratory for further evaluation, classification and testing. 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 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 characteristics. Atterberg limits tests are used to determine soil plasticity. The percent passing the #200 size sieve (-200 wash test) is used to determine the percentage of fine grained soils (clay and silt) in a sample. Swell/consolidation tests are performed to evaluate soil volume change potential with variation in moisture content. The results of the completed laboratory tests described above are outlined on the attached boring logs and swell/consolidation test summaries. Water Soluble Sulfates (WSS) tests were also completed on selected soil samples to evaluate corrosive soil characteristics with respect to buried concrete and are discussed subsequently in this report. SUBSURFACE CONDITIONS The subsurface materials encountered in the completed site borings can be summarized as follows. A thin layer of vegetation and topsoil was encountered at ground surface at each of the boring locations. The vegetative soil layer was typically underlain by reddish brown sandy lean clay with varying amounts of gravel, varying to silty/clayey sand in places. A portion of the near-surface lean clay and silty/clayey sand extending to depths between approximately 2½ to 4½ feet below ground surface in borings B-4 through B-9 Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 4 appeared to be fill soils placed to develop finish site grades. The lean clay and silty/clayey sand varied from stiff to very stiff in terms of consistency or loose to medium dense in terms of relative density and exhibited no to low sell potential at current moisture and density conditions. The lean clay and silty/clayey sand extended to depths ranging from approximately 8 to 9½ feet below ground surface and was underlain by brown/grey claystone bedrock. The claystone varied from weathered to very hard in terms of hardness, exhibited low to moderate swell potential at in-situ moisture and density conditions and extended to the bottom of boring at depths ranging from approximately 15 to 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 several of the completed site borings at the time of drilling. When checked approximately seven (7) days after completion of drilling, groundwater was measured at depths of approximately 4, 5, 5, 3½, 5, 4, 4, 4, and 1 foot below ground surface at boring locations B-1 and B-3 through B-10 respectively. Boring B-2 was observed to be dry to the depth explored (approximately 14 feet) at that time. 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 and/or trapped water can also vary over time. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 5 ANALYSIS AND RECOMMENDATIONS General Up to approximately 4½ feet of probable existing fill material was encountered near surface in a portion of the completed site borings. Based on provided site topography, a portion of the site appears to have been filled to develop finish grades. While the apparent fill soils were observed to be relatively consistent in terms of consistency and relative density and exhibited no to low swell potential at in-situ moisture and density conditions, we are unaware if this fill material was monitored and tested for moisture and density control at the time of placement and compaction and records of control during placement have not been provided. Inherent risks exist when using undocumented fill soils for support of footing foundations and floor slab improvements. Unless documentation of the control of this fill can be provided to Soilogic for review prior to construction, the only way to be sure excessive movement of footing foundations and floor slabs will not occur subsequent to construction would be to completely remove any existing fill to natural underlying lean clay or silty/clayey sand level and backfill the removed materials as low volume change (LVC), controlled and compacted, moisture- conditioned fill where applicable. Therefore, in order to reduce the potential for excessive total and differential foundation movement in undocumented fill areas and to develop consistent LVC potential foundation bearing and floor slab support, we recommend overexcavation/backfill procedures of all existing fill soils be completed to redevelop controlled and compacted, moisture-conditioned fill beneath all footing foundations and floor slabs, thereby reducing the potential for post-construction movement of those improvements. Recommendations concerning overexcavation/backfill procedures to redevelop controlled and compacted LVC-potential foundation and floor slab support are outlined below. Similar procedures should be considered in exterior flatwork and pavement areas. Based on the results of completed field and laboratory testing and if the records of control during placement of the existing fill can be located and provided to this office for review prior to construction, utilizing the existing fill for direct support of spread footing foundations, floor slabs, exterior flatwork and site pavements may be possible. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 6 Groundwater was measured in nine (9) of the ten (10) completed site borings at depths ranging from approximately 1 to 5 feet below ground surface when checked about 7 days after the completion of drilling. Boring B-2 remained dry to the approximate depth explored (14 feet) at that time. As a precaution, we recommend limiting finish floor slab elevations to at least three (3) feet above the level of water observed in order to account for some seasonal fluctuation in the level of groundwater and to reduce the potential for water infiltration in the crawl-space areas (if any), as well as to reduce the potential for disturbance of the bearing/subgrade soils and the requirement of soft/loose ground stabilization measures. The site soils would be expected to be soft/loose near current groundwater levels and would be easily disturbed by the construction activities. Care should be taken at the time of construction to avoid disturbing all foundation bearing soils and those site soils expected to receive fill and the resultant need for corrective action. To reduce the potential of disturbance of foundation bearing soils and the requirement for corrective work, we suggest the residence excavations be completed remotely with a track-hoe. If fills greater than approximately 5 feet will be required to develop finish site grades, the potential for consolidation of the underlying lean clay/clayey sand should be further evaluated. As a precaution, we recommend fill soils required to develop the site be placed and allowed to remain in place for as long as possible prior to construction in order to allow for consolidation of the underlying soils. Careful observation of the exposed foundation bearing materials should be completed at the time of construction to ensure all footing foundations will be supported on natural materials with suitable strength and low volume change potential. If extensive zones of existing fill or very loose/soft soils are encountered at that time, some overexcavation/ backfill or other approved stabilization procedures may be required prior to foundation construction. Site Development All existing topsoil and vegetation should be completely removed from the residence, garage, exterior flatwork and pavement areas. In addition, all existing fill soils should be Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 7 completely removed to natural undisturbed soil level (if documentation regarding control during fill placement cannot be provided) in these areas. Dewatering removal excavations extended below groundwater should be expected. After stripping and completing all cuts and removal procedures (if required) and prior to the placement of any new fill, flatwork concrete or site pavements, 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 reconditioned subgrade 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 finish site grade should consist of approved 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 and silty/clayey sand (natural and existing fill) could be used as fill to develop the site. Import materials (if required) should be approved prior to use and should have a maximum liquid limit of 40, maximum plasticity index of 18 and should contain a minimum of 25% fines in order to reduce the ability of those materials to pond and transmit water. We recommend suitable fill materials be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted as recommended for the scarified materials above. Care should be taken to avoid disturbing reconditioned subgrade soils and placed fill soils prior to construction of the overlying improvements. 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 concrete placement. Foundations Based on the materials encountered in the completed site borings and results of laboratory testing, it is our opinion the proposed townhome residences and bank garage structures could be supported by continuous spread footing and isolated pad foundations bearing on natural, undisturbed lean clay and/or controlled and compacted removal area backfill (if necessary). As a precaution, we recommend maintaining a minimum separation distance of three (3) feet between claystone bedrock and proposed foundation bearing elevation. Careful evaluation of the proposed foundation bearing materials Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 8 should be completed at the time of excavation to ensure all footing foundations will bear on like LVC materials with suitable strength. In addition, moisture/density testing of all removal area backfill soils expected to receive overlying improvements should be completed. For design of footing foundations bearing on natural, undisturbed stiff to very stiff lean clay, loose to medium dense silty/clayey sand and/or properly placed and compacted fill and backfill developed as outlined above, we recommend using a maximum net allowable soil bearing pressure of 1,500 psf. As a precaution, we recommend the footing foundations be designed to maintain a minimum dead-load pressure of 500 psf (or as high as practical) on the bearing soils. Exterior footings should bear a minimum of 30 inches below finished adjacent exterior grade to provide frost protection. We recommend formed strip footings have a minimum width of 12 inches and isolated pad foundations have a minimum width of 24 inches in order to facilitate construction and reduce the potential for development of eccentrically loaded footings. Actual footing widths should be designed by a structural engineer. For design of footing foundations and foundation walls to resist lateral movement, a passive equivalent fluid pressure value of 250 pcf could be used. The top 30 inches of subgrade could be considered a surcharge load but should not be used in the passive resistance calculations. A coefficient of friction of 0.35 could be used between foundation and floor slab concrete and the bearing soils to resist sliding. The recommended passive equivalent fluid pressure value and coefficient of friction do not include a factor of safety. Care should be taken to avoid disturbing the exposed foundation bearing materials after demolition and excavation. Disturbed soils or soils which are allowed to become wetted or dried prior to foundation construction should be removed and replaced or reworked in place prior to concrete placement. We estimate settlement of footing foundations designed and constructed as outlined above and resulting from the assumed structural loads would be less than 1 inch. Differential settlement could approach the amount of total settlement estimated above. If water from any source is allowed to infiltrate the foundation bearing soils, additional movement of the foundations could occur. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 9 Floor Slabs and Exterior Flatwork The building and detached garage floor slabs and exterior flatwork could be supported directly on the reconditioned subgrade soils or properly placed and compacted fill and overexcavation/backfill soils developed as outlined in the ‘Demolition and Site Development’ portion of this report. Subgrade soils expected to receive flatwork concrete should be evaluated closely immediately prior to concrete placement. Soils which have been 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 fill or overlying improvements. As a precaution, we recommend any partition walls constructed above slabs-on-ground be constructed as floating walls to help reduce the potential for differential slab-to- foundation movement causing distress in upper sections of the structures. A minimum 1½ inch void space is recommended beneath all floating walls. Special attention to door framing, drywall installation and trim carpentry should be taken to isolate those elements from the floor slabs, allowing for some differential floor slab to foundation movement to occur without transmitting stresses to the overlying structures. Depending on the type of floor covering and floor covering adhesive used in finished slab on ground areas, a vapor barrier may be required immediately beneath the floor slabs in order to maintain flooring product manufacturer warranties. A vapor barrier would help reduce the transmission of moisture through the floor slabs. However, the unilateral moisture release caused by placing concrete on an impermeable surface can increase slab curl. The amount of slab curl can be reduced by careful selection of an appropriate concrete mix. Slab curl cannot be eliminated. We recommend the owner, architect and flooring contractor consider the performance of the slab in conjunction with the proposed flooring products to help determine if a vapor barrier will be required and where best to position the vapor barrier in relation to the floor slab. Additional guidance and recommendations concerning slab-on-grade design can be found in American Concrete Institute (ACI) section 302. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 10 Crawl Space Construction We recommend perimeter drain systems be constructed around all crawl space areas (if any) to help reduce the potential for water infiltration into the crawl space areas and/or the development of hydrostatic pressures behind the foundation walls. The perimeter drain systems should consist of 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 systems. The invert of the drain pipes, at high points, should be placed at approximate foundation bearing level, run around the interior perimeters of the crawl space areas with a minimum slope of ⅛-inch per foot to facilitate efficient water removal and designed to discharge to daylight or sump pump and pit systems. If gravity outfalls will be constructed, flap-gates or other approved methods should be employed to reduce the potential for reverse flow and/or animal access into the systems. As an additional precaution, vapor barriers should be placed in all crawl space areas in order to help maintain in-situ soil moisture conditions and reduce the potential for migration of soil moisture into the crawl space areas. The subgrades in the crawl space areas should be graded to provide positive gravity drainage to the perimeter drain systems in the event of water infiltration into these areas. The owner/client should consider consulting with a mold prevention specialist for additional precautions that could be implemented to reduce the potential for development of moist air conditions in the crawl space areas of the townhomes. Backfill placed adjacent to the foundation should consist of LVC-potential and relatively impervious soils free from organic matter, debris and other objectionable materials. Native site lean clay, silty/clayey sand and existing fill could be used as backfill in these areas provided the proper moisture content is developed in those materials at the time of placement and compaction. We recommend the existing fill, native site lean clay, silty/clayey sand and/or similar backfill materials be placed in loose lifts not to exceed 9 inches thick, adjusted to within ±2% of standard Proctor optimum moisture content and compacted to at least 95% of the material’s standard Proctor maximum dry density. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 11 Excessive lateral stresses can be imposed on foundation walls when using heavier mechanical compaction equipment. We recommend compaction of unbalanced foundation wall backfill soils be completed using light mechanical or hand compaction equipment. Lateral Earth Pressures For design of unbalanced foundation walls where preventative measures have been taken to reduce the potential for development of hydrostatic pressures on the walls, we recommend using an active equivalent fluid pressure value of 40 pounds per cubic foot. Some rotation of the foundation walls must occur to develop the active earth pressure state. That rotation can result in cracking of the foundation walls typically in between corners and other restrained points. The amount of deflection of the top of the wall can be estimated at 0.5% times the height of the wall. An equivalent fluid pressure value of 60 pounds per cubic foot could be used for restrained wall conditions. Variables that affect lateral earth pressures include, but are not limited to; the swell potential of the backfill soils, backfill compaction and geometry, wetting of the backfill soils, surcharge loads and point loads developed in the backfill materials. The recommended equivalent fluid pressure values do not include a factor of safety or an allowance for hydrostatic loads. Use of expansive soil backfill, excessive compaction of wall backfill or surcharge loads placed adjacent to the foundation walls can add to the lateral earth pressures, causing the equivalent fluid pressure values used in design to be exceeded. Seismicity Based on our review of the International Building Code (2003), a soil profile type D could be used for the site strata. Based on our review of United States Geologic Survey (USGS) mapped information, design spectral response acceleration values of SDS = .231 (23.1%) and SD1 = .094 (9.4%) could be used. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 12 Site Pavements Site pavements could be supported directly on suitable subgrade soils developed as outlined in the “Site Development” section of this report. Pavement subgrades are expected to consist of reconditioned sandy lean clay and silty/clayey sand. The lean clay and silty/clayey sand would be subject to low remolded shear strength. A resistance value (R-value) of 5 was estimated for the subgrade soils and used in the pavement section design. Traffic loading on the site pavements is expected to consist of areas of low volumes of automobiles and light trucks, as well as areas of higher light vehicle traffic volumes and occasional heavier trash and delivery trucks. Equivalent 18-kip single axle loads (ESAL’s) were estimated for the quantity of site traffic anticipated. Two (2) general pavement design classifications are outlined below in Table I. Standard duty pavements could be considered in automobile drive and parking areas. Heavy duty pavements should be considered for access drives and other areas of the site expected to receive higher traffic volumes or heavy truck traffic. The heavy-duty pavement section option matches the pavement section design completed for the site roadways under LCUASS provided under separate cover. Proofrolling of the pavement subgrades should be completed to help identify unstable areas. Depending on finish site grades, the in place moisture content of the subgrade soils immediately prior to paving, the time of year when construction occurs and other hydrologic conditions, stabilization of the subgrade soils may become necessary to develop a suitable paving platform. If required, we recommend consideration be given to stabilization of the pavement subgrades with class C fly ash. With the water-soluble sulfate concentration of the site soils determined in laboratory testing, it is our opinion stabilization with Portland cement could also be considered for this project. With the increase in support strength developed by the chemical stabilization procedures, it is our opinion some credit for the chemically stabilized zone could be included in the pavement section design, reducing the required thickness of overlying asphaltic concrete and aggregate base course. Chemical stabilization can also eliminate some of the uncertainty associated with attempting to pave during periods of inclement weather. Pavement section design options incorporating some structural credit for the chemically-stabilized subgrade soils are outlined below in Table I. Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 13 TABLE I – PAVEMENT SECTION DESIGN Standard Duty Heavy Duty Option A – Composite Asphaltic Concrete (Grading S or SX) Aggregate Base (Class 5 or 6) 4” 6” 4½” 7” Option B – Composite on Stabilized Subgrade Asphaltic Concrete (Grading S or SX) Aggregate Base (Class 5 or 6) Fly Ash of Cement Stabilized Subgrade 3” 4” 12” 4” 6” 12” Option C - Portland Cement Concrete Pavement PCCP 5” 6” Asphaltic concrete should consist of a bituminous plant mix composed of a mixture of aggregate, filler, binders and additives if required meeting the design requirements of the City of Fort Collins. Aggregate used in the asphaltic concrete should meet specific gradation requirements such as Colorado Department of Transportation (CDOT) grading S (¾-inch minus) or SX (½-inch minus) specifications. Hot mix asphalt designed using “Superpave” criteria should be compacted to within 92 to 96% of the materials Maximum Theoretical Density. Aggregate base should be consistent with CDOT requirements for Class 5 or Class 6 aggregate base, placed in loose lifts not to exceed 9 inches thick and compacted to at least 95% of the materials standard Proctor maximum dry density. If chemical stabilization procedures will be completed, we recommend the addition of 13% class ‘C’ fly ash or 5% Portland cement based on component dry unit weights. A 12-inch thick stabilized zone should be constructed by thoroughly blending the fly ash/cement with the in-place subgrade soils. Some “fluffing” of the finish subgrade level should be expected with the stabilization procedures. The blended materials should be adjusted in moisture content to within the range of ±2% of standard Proctor optimum moisture content and compacted to at least 95% of the material’s standard Proctor maximum dry density within two (2) hours of fly ash addition or immediately after cement addition. For areas subjected to truck turning movements and/or concentrated and repetitive loading such as dumpster or truck parking and loading areas, we recommend consideration be given to the use of Portland cement concrete pavement with a minimum thickness of 6 inches. The concrete used for site pavements should be air entrained and Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 14 have a minimum 28-day compressive strength of 4,000 psi. Woven wire mesh or fiber entrained concrete should be considered to help in the control of shrinkage cracking. The proposed pavement section designs do not include an allowance for excessive loading conditions imposed by heavy construction vehicles or equipment. Heavily loaded concrete or other building material trucks and construction equipment can cause some localized distress to site pavements. The recommended pavement sections are minimums and periodic maintenance efforts should be expected. A preventative maintenance program can help increase the service life of site pavements. Corrosive Soil Characteristics We measured the soluble sulfate concentration for two (2) representative samples of the subsoils which will likely be in contact with structural concrete. The sulfate concentrations measured in the samples varied from 0 to 150 parts per million. ACI rates the measured concentrations as being defined as a “negligible risk” category for concrete sulfate attack; therefore Type I cement should be suitable for concrete members on and below grade. As an added precaution, Type I/II Portland cement could be considered for additional sulfate resistance of construction concrete. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Drainage Positive drainage is imperative for satisfactory long-term performance of the proposed buildings and associated site improvements. We recommend positive drainage be developed away from the structures during construction and maintained throughout the life of the site improvements, with twelve (12) inches of fall in the first 10 feet away from the buildings. Shallower slopes could be considered in hardscape areas. In the event that some settlement of the building backfill soils occurs over time, the original grade and associated positive drainage outlined above should be immediately restored. Care should be taken in the planning of landscaping to avoid features which could result in the fluctuation of the moisture content of the foundation bearing and flatwork and pavement subgrade soils. We recommend watering systems be placed a minimum of 5 feet away Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 15 from the perimeters of the site structures and be designed to discharge away from all site improvements. Gutter systems should be considered to help reduce the potential for water ponding adjacent to the structures with the gutter downspouts, roof drains or scuppers extended to discharge a minimum of 5 feet away from structural, flatwork and pavement elements. Water which is allowed to pond adjacent to site improvements can result in unsatisfactory 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. 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 Geotechnical Subsurface Exploration Report Manhattan Townhomes 3836 Manhattan Avenue, Fort Collins, Colorado Soilogic # 15-1090 16 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 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 6" VEGETATION & TOPSOIL - 1 - 2 CL LEAN CLAY WITH SAND AND GRAVEL - reddish brown 3 CS 14 15.2 112.6 9000+ - - - - - stiff to very stiff - 4 - 5 CS 20 15.9 117.7 7500 - - 39 22 75.9% - 6 - 7 - 8 - 9 - 10 CS 50/8 16.9 109.1 9000+ 3.8% 4250 - - - CLAYSTONE - grey/brown 11 hard to very hard - 12 - 13 - 14 - 15 CS 50/7 16.4 113.8 9000+ 1.1% 3250 - - - - 16 - 17 - 18 - 19 - 20 CS 50/5 15.4 115.7 9000+ - - - - - - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-2 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 7" VEGETATION & TOPSOIL - 1 - 2 CL SANDY LEAN CLAY WITH GRAVEL - reddish brown 3 stiff - 4 - 5 CS 14 11.5 120.6 5000 None <500 - - - - 6 - 7 - 8 - 9 - 10 CS 29 18.4 110.7 9000+ 3.1% 5000 - - - CLAYSTONE - grey/brown 11 firm to very hard - 12 - 13 - 14 - 15 CS 50/4 21.1 110.6 9000+ - - - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-3 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 5" VEGETATION & TOPSOIL - 1 - 2 CL SANDY LEAN CLAY WITH GRAVEL - reddish brown 3 stiff - 4 - 5 CS 13 16.7 116.3 <500 - - - - - - 6 - 7 - 8 - 9 - 10 CS 15 21.3 101.3 6000 0.8% 1000 - - - CLAYSTONE - grey/brown 11 weathered to hard - 12 - 13 - 14 - 15 CS 50/8 20.3 104.8 9000+ 1.0% 2900 - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-4 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 6" VEGETATION & TOPSOIL - 1 Probable Existing Fill - CL SANDY LEAN CLAY WITH GRAVEL 2 reddish brown - very stiff 3 CS 21 13.3 114.2 6000 0.1% 600 - - - - 4 - CL SANDY LEAN CLAY WITH GRAVEL 5 CS 17 15.6 111.7 9000+ - - - - - reddish brown - stiff to very stiff 6 - 7 - 8 - 9 - 10 CS 23 20.4 102.9 9000+ 1.1% 1500 - - - - 11 - CLAYSTONE 12 grey/brown - weathered to very hard 13 - 14 - 15 CS 50/5 20.7 105.5 9000+ - - - - - - 16 - 17 - 18 - 19 - 20 CS 50/4 17.9 109.9 9000+ - - - - - - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-5 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 5" VEGETATION & TOPSOIL - 1 Probable Existing Fill - CL SANDY LEAN CLAY WITH GRAVEL 2 reddish brown - stiff 3 - 4 - 5 CS 12 13.4 110.6 <500 - - - - - SM-SC SILTY/CLAYEY SAND - reddish brown 6 loose - 7 - 8 - 9 - 10 CS 18 25.1 99.5 4000 0.8% 1100 - - - CLAYSTONE - grey/brown 11 weathered to hard - 12 - 13 - 14 - 15 CS 50/7 17.1 113.9 9000+ - - - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-6 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 3" VEGETATION & TOPSOIL - 1 Probable Existing Fill - CL SANDY LEAN CLAY 2 reddish brown - very stiff 3 CS 26 15.7 111.5 9000+ 1.2% 1900 - - - - 4 - 5 CS 15 14.9 116.3 4000 - - - - - CL SANDY LEAN CLAY WITH GRAVEL - reddish brown 6 stiff - 7 - 8 - 9 - 10 CS 14 21.4 107.2 4000 0.5% 1100 - - - - 11 CLAYSTONE - grey/brown 12 weathered to very hard - 13 - 14 - 15 CS 50/6 20.7 113.0 9000+ - - - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-7 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 5" VEGETATION & TOPSOIL - 1 - Probable Existing Fill 2 CL SANDY LEAN CLAY WITH GRAVEL - reddish brown 3 very stiff - 4 - 5 CS 32 6.1 125.1 N/A - - - - - - SM-SC SILTY/CLAYEY SAND WITH GRAVEL 6 reddish brown - medium dense 7 - 8 - 9 - 10 CS 22 23.3 100.2 6000 0.1% 600 - - - CLAYSTONE - grey/brown 11 weathered to medium hard - 12 - 13 - 14 - 15 CS 45 22.1 104.9 5000 0.8% 1750 - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-8 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 6" VEGETATION & TOPSOIL - Probable Existing Fill 1 CL SANDY LEAN CLAY - reddish brown 2 very stiff - 3 CS 19 12.1 117.3 7500 - - - - - - CL SANDY LEAN CLAY WITH GRAVEL 4 reddish brown - stiff 5 CS 16 20.0 110.2 4000 None <500 - - - - 6 - 7 - 8 - 9 - 10 CS 23 19.8 107.0 9000+ 0.8% 1750 - - - CLAYSTONE - grey/brown 11 weathered to hard - 12 - 13 - 14 - 15 CS 50/9 19.3 114.9 9000+ - - - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-9 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 6" VEGETATION & TOPSOIL - 1 - Probable Existing Fill 2 CL SANDY LEAN CLAY/CLAYEY SAND - reddish brown 3 very stiff/medium dense - 4 - 5 CS 20 15.7 115.4 5000 0.1% 600 35 16 42.1% - CL SANDY LEAN CLAY WITH GRAVEL 6 reddish brown - very stiff 7 - 8 - 9 - 10 CS 19 20.2 108.4 6000 0.9% 1500 - - - - 11 - 12 - CLAYSTONE 13 grey/brown - weathered to very hard 14 - 15 CS 50/8 16.9 111.9 9000+ - - - - - - 16 - 17 - 18 - 19 - 20 CS 50/4 17.3 108.7 9000+ - - - - - - 21 - 22 - 23 - 24 - 25 - LOG OF BORING B-10 1/1 Mobile B50 4" CFA Manual BMc Estimated Swell % Passing SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve (ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%) 0 - 6" VEGETATION & TOPSOIL - 1 - 2 CL SANDY LEAN CLAY WITH GRAVEL - reddish brown 3 very stiff - 4 - 5 CS 22 16.9 112.3 9000+ None <500 - - - - 6 - 7 SC CLAYEY SAND - reddish brown 8 medium dense - 9 - 10 CS 15 22.5 101.3 5000 - - - - - - 11 - CLAYSTONE 12 grey/brown - weathered to hard 13 - 14 - 15 CS 50/9 17.1 111.1 9000+ 1.7% 4500 - - - BOTTOM OF BORING @ 15.0' - 16 - 17 - 18 - 19 - 20 - 21 - 22 - 23 - 24 - 25 - Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 109.1 pcf Sample Description: Grey/Brown Claystone Sample ID: B-1 @ 9' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY 3.8% 4,250 psf Initial Moisture Final Moisture % Swell @ 500 psf Swell Pressure 16.9% 23.1% -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 113.8 pcf Final Moisture 20.2% % Swell @ 1,000 psf 1.1% Swell Pressure 3,250 psf Sample ID: B-1 @ 14' Sample Description: Grey/Brown Claystone Initial Moisture 16.4% MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 120.6 pcf Final Moisture 13.0% % Swell @ 500 psf None Swell Pressure <500 psf Sample ID: B-2 @ 4' Sample Description: Reddish Brown Sandy Lean Clay with Gravel (CL) Initial Moisture 11.5% MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 110.7 pcf Final Moisture 22.8% % Swell @ 500 psf 3.1% Swell Pressure 5,000 psf Sample ID: B-2 @ 9' Sample Description: Grey/Brown Claystone Initial Moisture 18.4% MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 101.3 pcf Final Moisture 25.6% % Swell @ 500 psf 0.8% Swell Pressure 1,000 psf Sample ID: B-3 @ 9' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 21.3% MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 104.8 pcf Final Moisture 23.8% % Swell @ 1,000 psf 1.0% Swell Pressure 2,900 psf Sample ID: B-3 @ 14' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 20.3% MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 114.2 pcf Final Moisture 17.6% % Swell @ 500 psf 0.1% Swell Pressure 600 psf Sample ID: B-4 @ 2' Sample Description: Fill - Reddish Brown Sandy Lean Clay with Gravel (CL) Initial Moisture 13.3% MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 102.9 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-4 @ 9' Sample Description: Grey/Brown Claystone Initial Moisture 20.4% Final Moisture 24.1% % Swell @ 500 psf 1.1% Swell Pressure 1,500 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 99.5 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-5 @ 9' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 25.1% Final Moisture 26.1% % Swell @ 500 psf 0.8% Swell Pressure 1,100 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 111.5 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-6 @ 2' Sample Description: Fill - Brown/Grey Sandy Lean Clay (CL) Initial Moisture 15.7% Final Moisture 18.9% % Swell @ 500 psf 1.2% Swell Pressure 1,900 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 107.2 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-6 @ 9' Sample Description: Rust/Olive/Brown Claystone Initial Moisture 21.4% Final Moisture 22.2% % Swell @ 500 psf 0.5% Swell Pressure 1,100 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 100.2 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-7 @ 9' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 23.3% Final Moisture 23.3% % Swell @ 500 psf 0.1% Swell Pressure 600 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 104.9 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-7 @ 14' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 22.1% Final Moisture 23.1% % Swell @ 500 psf 0.8% Swell Pressure 1,750 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 110.2 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-8 @ 4' Sample Description: Reddish Brown Sandy Lean Clay with Gravel (CL) Initial Moisture 20.0% Final Moisture 20.3% % Swell @ 500 psf None Swell Pressure <500 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 107.0 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-8 @ 9' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 19.8% Final Moisture 20.2% % Swell @ 500 psf 0.8% Swell Pressure 1,750 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 115.4 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-9 @ 4' Sample Description: Reddish Brown Sandy Lean Clay with Gravel (CL) Initial Moisture 15.7% Final Moisture 17.4% % Swell @ 500 psf 0.1% Swell Pressure 600 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 108.4 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-9 @ 9' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 20.2% Final Moisture 21.3% % Swell @ 500 psf 0.9% Swell Pressure 1,500 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 112.3 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-10 @ 4' Sample Description: Reddish Brown Sandy Lean Clay (CL) Initial Moisture 16.9% Final Moisture 18.7% % Swell @ 500 psf None Swell Pressure <500 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Liquid Limit - Plasticity Index - % Passing #200 - Dry Density 111.1 pcf MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 SWELL/CONSOLIDATION TEST SUMMARY Sample ID: B-10 @ 14' Sample Description: Grey/Rust/Olive/Brown Claystone Initial Moisture 17.1% Final Moisture 21.1% % Swell @ 1,000 psf 1.7% Swell Pressure 4,500 psf -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 10 100 1000 10000 100000 --------- Applied Load (psf) Resistivity (ohms-cm) Corrosion Condition < 2,300 very aggressive 2,300- 5,000 moderately aggressive 5,000- 10,000 slightly aggressive > 10,000 non- aggressive Aggressivity Aggressivity pH Range Acid/Base to Lead to Iron and Steel < 4 extremely acidic very aggressive very aggressive 4.0- 4.5 very acidic very aggressive very aggressive 4.5- 5.0 acidic slightly aggressive very aggressive 5.0-6.0 slightly acidic slightly aggressive very aggressive 6.0- 6.5 slightly acidic slightly aggressive aggressive 6.5- 7.5 neutral non- aggressive non- aggressive 7.5- 8.5 slightly alkaline non- aggressive non- aggressive > 8.5 very alkaline very aggressive doubtful Exposure In water (ppm) Negligible < 150 Moderate 150 to 1500 Severe 1500 to 10000 Very Severe > 10000 ACI 318-11 " Corrosion of Metals in the Underground and Underground Telephone Plant" by George Schick, Bell Telephone Laboratories In soil, percent by weight < 0.1 (Level of Sulfate Attack of Concrete Exposed to Soils) CORROSIVE SOIL CHARACTERISTICS (Degree of Aggression for Corrosion of Buried Ferrous Metals Exposed to Soil) (Degree of Aggression for Corrosion of Buried Lead, Iron and Steel Exposed to Soil) 0.1 to 0.2 0.2 to 2.0 > 2.0 WATER SOLUBLE SULFATES Concentration of soluble sulfates expressed as SO4 SOIL RESISTIVITY SOIL pH UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification Group Symbol Group NameB Clean Gravels Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF 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 Clean Sands Cu ! 6 and 1 " Cc " 3E SW Well graded sandI 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 Silts and Clays PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M 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 Organic Liquid limit - oven dried Organic clayK,L,M,P 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 = 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+ 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. 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling 1' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling 6' Finish Date 4/14/2015 Hammer Type: After Drilling 6' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - BOTTOM OF BORING @ 30.0' 30 CS 50/4 14.4 105.5 9000+ - - - - - Surface Elev. - Field Personnel: 7 Days After Drilling 4' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling 10' Finish Date 4/14/2015 Hammer Type: After Drilling 10' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling 4' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling 9.5' Finish Date 4/14/2015 Hammer Type: After Drilling 9.5' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling 4' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling 9.5' Finish Date 4/14/2015 Hammer Type: After Drilling 9.5' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling 5' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling 10' Finish Date 4/14/2015 Hammer Type: After Drilling 10' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling 3.5' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling None Finish Date 4/14/2015 Hammer Type: After Drilling None MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - BOTTOM OF BORING @ 30.0' 30 CS 50/3 17.9 110.5 9000+ - - - - - Surface Elev. - Field Personnel: 7 Days After Drilling 5' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling 9.5' Finish Date 4/14/2015 Hammer Type: After Drilling 9.5' MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling 5' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling None Finish Date 4/14/2015 Hammer Type: After Drilling None MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - 30 Surface Elev. - Field Personnel: 7 Days After Drilling Dry @ 14' USCS Sampler Atterberg Limits Start Date 4/14/2015 Auger Type: During Drilling None Finish Date 4/14/2015 Hammer Type: After Drilling None MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information 26 - 27 - 28 - 29 - BOTTOM OF BORING @ 30.0' 30 CS 50/4 18.3 115.1 9000+ - - - - - MANHATTAN TOWNHOMES 3836 MANHATTAN AVENUE, FORT COLLINS, COLORADO Project # 15-1090 April 2015 Sheet Drilling Rig: Water Depth Information Start Date 4/14/2015 Auger Type: During Drilling None Finish Date 4/14/2015 Hammer Type: After Drilling None Surface Elev. - Field Personnel: 7 Days After Drilling 4' USCS Sampler Atterberg Limits