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Home My WebLink AboutARROWHEAD COTTAGES - MJA/FDP - FDP160004 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTSUBSURFACE EXPLORATION REPORT RESIDENTIAL HIGH RISE CONDOMINIUM PROJECT CENTER FOR ADVANCE TECHNOLOGY P.U.D. - 7" FILING FORT COLLINS, COLORADO EEC PROJECT NO. 1082101 October 13, 2008 Attn: Mr. Stan Everitt Re: Subsurface Exploration Report Residential High Rise Condominium Project Centre for Advanced Technology P.U.D. - 7 1h Filing Fort Collins, Colorado EEC Project No, 108210,1 Enclosed herewith, are the results of the subsurface exploration completed by Earth Engineering Consultants, Inc. for the referenced project, For this study a total of four (4) soil borings were drilled on September 22, 2008 within the proposed site improvement/development areas at locations accessible to our drilling equipment. The borings were extended to approximate depths of 15 to 30- feet below existing site grades. This study was completed in general accordance with our proposal dated September 15, 2008. We understand this project involves the construction of three (3) residential "high-rise" condominium structures, and an associated pavement area, planned for construction at the northeast comer of Centre Avenue and Worthington Circle on Tracts A and C of the Centre for Advanced Technologies - 7'h Filing in Fort Collins, Colorado. The residential buildings will be 3-story structures with slab -on -grade or partial/garden level construction. The majority of the site is a concrete paved parking area, portions used by the adjoining property (N,T.tJ,), which will be removed to accommodate the proposed construction. EEC located the test borings at selected areas to avoid impacting the existing site conditions, In summary, approximately 6 to 9-inches of topsoil containing organic matter and root growth, was encountered at the surface of each boring. Native, essentially cohesive subsoils, classified as sandy lean clay, lean clay, and clayey sand were encountered beneath the surficial layer and extended to the depths explored or to the course granular stratum below. In the deeper borings, (ie., soil borings B-2 and B-4) a course clayey sand and/or silty sand with gravel was encountered beneath the upper cohesive materials and extended to the depths explored, approximately 30-feet below site grades. 4396 GREENFIELD DRIVE WINDSOR, COLORADO 80550 (970) 545-3908 FAX (970), 6163-0282 Eailh Engincefing Consuilants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 2 At the time of drilling, free water was observed in soil borings B-1 through B-3 at approximate depths of 13-1/2 to 18-feet below site grades. Groundwater was not encountered in boring B-4 to maximum depths of exploration, approximately 15-feet. When checked several days after drilling, groundwater was measured in borings B-I through B-3 at approximate depths of 14-1/2 to 16-1/2- feet below site grades, while free water was still not observed in boring B-4 to maximum depths of exploration. Based on the subsurface conditions encountered in the test borings as well as the anticipated maximum loading conditions, we recommend the proposed 3-story, "high-rise" condominium structures be supported on conventional spread footings bearing on approved native subsoils or engineered fill material. Care will be needed to evaluate the anticipated bearing materials to verify that spread footing foundations are bearing on suitable materials. Footings should be placed on similar like material to reduce the potential for differential movement. We anticipate floor slabs, and exterior flatwork could be supported on newly placed and compacted fill soils or on ground modified native soils. Low to moderate swell was observed in the near surface cohesive subsoils. Care will be needed to evaluate the swell of near surface soils at the time of construction. Geotechnical recommendations concerning design and construction of the proposed site improvements are provided within the attached report. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning the enclosed report, or if we can be of further service to you in any other way, please do not hesitate to contact us. Very truly yours, Earth Engineering Consultants, Inc. David A. Richer, P.E. Senior Geotechnical Engineer Reviewed by: Lester L. Litton, P.E. Principal Engineer cc:Vaught Frye 1ipley Design - i ennifer. alm steadayfidesi gni tic. cgni SUBSURFACE EXPLORATION REPORT RESIDENTIAL HIGH RISE CONDOMINIUM PROJECT CENTER FOR ADVANCE TECHNOLOGY P.U.D. — 7"' FILING FORT COLLINS, COLORADO EEC PROJECT NO. 1082101 October 13, 2008 The geotechnical subsurface exploration for the proposed "high-rise" residential condominium project located at the northeast corner of Centre Avenue and Worthington Circle within the Centre for Advanced Technology P.U.D. — 7" Filing in Fort Collins, Colorado, has been completed. The site for the proposed development is situated within the North V2 of Section 23, Township 7 North, Range 69 West of 6 1h PM, Larimer County, Colorado. For this assessment a total of four (4) soil borings were drilled on September 22, 2009 and were extended to depths of appToximately 15 to 30-feet below present site grades. We understand this project involves the construction of three (3) residential "high-rise" buildings along with an associated pavement area. The buildings are planned as wood - framed with brick veneer, 3-story structures having slab -on -grade or partial/garden-level construction. Foundation loads for the structures are expected to be light to moderate with continuous wall loads less than 4 kips per lineal foot and individual column loads less than 150 kips. Floor loads are expected to be light. Included in the site development will be parking and drive areas surrounding the building footprints. Small grade changes are expected to develop final site grades. The purpose of this report is to described the subsurface conditions encountered in the test borings, analyze and evaluate the test data and provide geotechnical recommendations concerning design and construction of foundations, support of floor slabs, pavements and flatwork and development of site retaining walls and other features. EXPLORATION ANDTESTING PROCEDURES The test borings were completed using a truck mounted, CME-45 drill rig equipped vvith a hydraulic head employed in drilling and sampling operations. The borcholes were advanced Earth Engineering Consultants, Inc. EEC Project No. 1082101 October 13, 2008 Page 2 using 4-inch nominal diameter continuous flight augers. Samples of the subsurface materials encountered were obtained using split barrel and California barrel sampling procedures. In the split barrel and California barrel sampling procedures, standard sampling spoons are advanced into the ground by means of a 140-pound hammer failing a distance of 30 inches. The number of blows required to advance the split barrel and California barrel samplers is recorded and is used to estimate the in -situ relative density of coliesionless soils, and, to a lesser degree of accuracy, the consistency of cohesive soils. In the California barrel sampling procedure, relatively undisturbed samples are obtained in removable brass liners. All samples obtained in the field were sealed and returned to the laboratory for further examination, classification, and testing. Moisture content tests were completed on each of the recovered samples. Atterberg Limits and washed sieve analysis tests were completed to evaluate the quantity and plasticity of fines in the subgrade samples. Sell consolidation tests were completed to evaluate the potential for the subgrade materials to change volume with variation in moisture and load. Results of the outlined tests are indicated on the attached boring logs and summary sheets. As part of the testing program, all samples were examined in the laboratory by an engineer and classified in accordance with the attached General Notes and the Unified Soil Classification System, based on the soil's texture and plasticity. The estimated group symbol for the Unified Soil Classification System is indicated on the boring logs and a brief description of that classification system is included with this report. Classification of the bedrock was based on visual and tactual observation of disturbed samples and auger cuttings, SITE AND SUBSURFACE CONDITIONS The proposed "high-rise" residential condominium project site is located at the, northeast, corner of Worthington Circle and Centre Avenue within the CAT -7 1h Filing development in Fort Collins, Colorado. The majority of the site is currently overlain by a concrete paved parking area, used primarily by the adjoining property, (N.TU), as well as grass landscaped sections. We understand the pavement areas are to be removed to accommodate the new Earth Engineering Consultants, Inc. EEC Project No. 1082101 October 13, 2008 Page 3 construction. The site is relatively flat exhibiting, positive surface drainage in both the north direction toward the irrigation ditch, known as the New Mercer Ditch, which meanders along the northern boundary of the site, as well as to the south toward Centre Avenue. The N.T.U. facility is located to the east and additional filings within the CAT Development beyond Centre Avenue are to the south. Based on results of the field borings and laboratory testing, subsurface conditions can be generalized as follows. In summary, approximately 6 to 8-inches of topsoil containing organic matter and root growth, was encountered at the surface of each boring. Native, essentially cohesive subsoils, classified as sandy lean clay, lean clay, and clayey sand were encountered beneath the surf cial layer, and extended to the depths explored or to the course granular stratum below. In the deeper borings, (i.e., soil borings B-2 and B-4) course clayey sand and/or silty sand with gravel was encountered beneath the upper cohesive materials and extended to the depths explored, approximately 0-feet below site grades. The native cohesive soils exhibited a low to moderate expansive potential upon inundation with water, were medium stiff to stiff in consistency, and exhibited low to moderate bearing capacity characteristics. The fine to coarse granular sand and gravel lenses were medium dense to dense, exhibited moderate bearing characteristics and were essentially non expansive. The stratification boundaries indicated on the boring logs, represent the approximate location's of changes in soil and rock types. In -situ, the transition of materials may be gradual and indistinct. GROUNDWATER CONDITIONS Observations were made while drilling and after completion of the borings, to detect the presence and depth to hydrostatic groundwater. At the time of drilling, free water was observed in soil borings 13- 1 through B-3 at approximate depths of 13-1/2 to 18-feet below site grades. Groundwater was not encountered in boring B-4 to the maximum depth of Fi4ab Engineering Consultants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 4 exploration, approximately 15-feet. Field -slotted I- I /2-inch nominal diameter PVC casing piezometers were installed in borings 13- 1, B-2, and B-3 to allow for subsequent groundwater measurement. When checked several days after drilling, groundwater was measured in borings 13- 1 through B-3 at approximate depths of 14-1/2 to 16-1/2-feet below site grades, white free water was still not observed, in boring BA to the maximum depth Of CXPIDTation. Fluctuations in groundwater levels can occur over time depending on variations in hydrologic conditions, and other conditions not apparent at the time of this report. Longer term monitoring of water levels in eased wells, which are sealed from the influence of surface water would be required to more accurately evaluate fluctuations in groundwater levels at the site. We have typically noted deepest groundwater levels in late winter and shallowest groundwater levels in mid to late summer. Zones of perched and/or trapped water can be encountered at times throughout the year in more permeable zones in the subgrade soils. ANALYSIS AND RECOMMENDATIONS General Considerations The site appears suitable for the proposed development based on the subsurface conditions observed; however certain precautions will be required in the design and construction addressing the expansive characteristics of the subsurface soils, and groundwater conditions at or near garden -levels and construction within close proximity to the adjacent New Mercer Ditch meandering along the northern, boundary of the site. EEC's soil borings were located within landscaped portions of the site, adjacent to existing pavement areas. It has been our experience dissimilar subgrade conditions can exist beneath pavement areas and non -pavement areas. Beneath pavement sections, wetter subgrade soils may exist, which are less expansive and potentially may be unstable, whereas in non -pavement areas, as evident by our swell consolidation test results, drier and potentially more expansive characteristics may exist. Care will be needed during construction to address for expansive and/or soft/compressible subgrade conditions. Firth Engineering Consoltants, Inc. EEC Project No. 108,2 101 October 13, 2008 Page 5 Depending upon the depth of excavation, (i.e., if lower level construction is being planned for), consideration should be given to installing an underdrain/underslab drainage system to intercept or control groundwater from impacting the lowest opening, Demolition of the existing concrete parking area should include complete removal of pavement, curb and gutter, and sidewalk materials within the proposed construction area. All materials derived from the demolition of the existing pavements should be removed from tile site and wasted from the site. Consideration could be given to pulverizing the concrete into 3-inch minus material and devoid of reinforcement, into structural fill material. Additional recommendations for reuse of the existing concrete material can be provided upon request. Although evidence of fills or underground facilities were not observed during the site reconnaissance, such features could be encountered during construction. if unexpected fills or underground facilities are encountered, such features should be removed and the excavation thoroughly cleaned prior to backfill placement an&or construction. Swell — Consolidation Test Results The swell -consolidation test is commonly performed to evaluate the swell or collapse potential of soils for determining foundation, floor slab and pavement desigm criteria. In this test, relatively undisturbed samples obtained directly from the ring barrel sampler are placed in a laboratory apparatus and inundated with water under a predetermined load. The swell -index is the resulting amount of swell or collapse as a percent of the sample's thickness after the inundation period. Samples obtained at approximate depths of I to 2-fact are generally pre - loaded at 150-psf to simulate the pavement loading conditions, while samples obtained at the 3 to 4-foot intervals are pre -loaded at 500 psf to simulate the overburden soil pressure, All samples are inundated with water and monitored for swell and consolidation. After the inundation period additional incremental loads are applied to evaluate the swell pressure and rate of consolidation, For this assessment, we conducted four (4) swell -consolidation tests at various intervals/deptbs throughout the site. The swell index values for the samples analyzed revealed low to moderate Earth Engineering Conwhants, tang. EEC Project No. 1 O'82 101 October 13, 2008 Page 6 swell characteristics on the order of 0.0 % to (+) 3,7 % The (+) test results indicate the swell potential characteristics of the soil upon inundation with water. Swett -mitigation techniques will be required for floor slab subgrade and may be required for the pavement/exterior flatwork subgrade, which will be discussed in the "Pavement Subgrade Section" of this report. Site_P,reparation Although final site grades were not available at the time of this report, based on our understanding of the proposed development, we expect about I to 3 -feet of fill material may be necessary to achieve design grades, depending upon slab -on -grade or garden -level construction. After stripping and completing all cuts and prior to placement of any fill or site improvements, we recommend the exposed soils be scarified to a minimum depth of 12- inches, adjusted in moisture content to within ±2% of standard Proctor optimum moisture content and compacted to at least 95% of the material's standard Proctor maximum dry density as determined in accordance with ASTM Specification D-698. Fill soils required for developing the building, pavement and site subgrades, should consist of approved, low -volume -change materials, which are free from organic matter and debris. It is our opinion the on -site cohesive clay soils could be used as general site fill, provided adequate moisture treatment and compaction procedures are followed. To minimize the potential amount of movement due to, swell potential of native subgrade soils or potentially unstable subgrade conditions beneath existing pavement sections, we suggest the use of an imported granular fill material such as a "'DOT Class 6 or 7 aggregate base course or recycled concrete material be placed and compacted within the upper 2-feet below slabs. We recommend fill materials be placed in loose lifts not to exceed 9 inches thick and adjusted in moisture content, generally +/- 2% of optimum moisture content, and compacted to at least 95% of the materials maximum dry density as determined in accordance with AST M Specification D-698, the standard Proctor procedure. :are should be exercised of preparation of the subgrades, to avoid disturbing the subgrade materials. Positive drainage should be developed away from the structures to, avoid wetting Ea"h Vtgintev inB C D11suhmAs' Int, EEC Project No. 1082 101 October 13, 2008 Page 7 of subgrade materials, Subgrade materials becoming wet subsequent to construction of the site structure can result in unacceptable performance. Spread Footing Foundation System The in -place cohesive soils are medium stiff to stiff and/or medium dense to dense with increased depth and appear suitable for support of conventional type spread footings, provided the maximum wall and column loads, do not exceed those as presented herein. If actual design loads are in excess of the assumed values discussed herein, additional recommendations, such as a deep foundation system or an extensive over -excavation replacement procedure may be necessary. Conventional type spread footings may be used to support the 3-story, wood -framed residential condominium structures provided the footings are placed on approved native subsoils and/or engineered fill material and the maximum anticipated wall and column loads do not exceed 4 klf and 150 kips respectively. If design loads exceed these values, as previously presented, the use of a deep foundation system or an over -excavation and replacement method should be implemented. Footings bearing on approved native subsoils, ground modified soils, or engineered fill material, should be designed for a maximum net allowable bearing pressure of 1,500 psf For upper level footings, (i.e., footings placed within the upper 3 to 5-foot zone below existing site grades), should also be designed to maintain a minimum dead load pressure of 500 psf due to the expansive characteristics of the lean clay subsoils. We estimate the long-term settlement of footing foundations designed and constructed as outlined above bearing, on native with the loads presented, would be about I -inch. Fill material, where necessary, and foundation backfill soils should be placed in loose lifts not to exceed 9 inches thick and adjusted to a moisture content of +/- 2 % of optimum moisture content, and compacted to at least 95% of standard Proctor maximum dry density per ASTM Specification D-6,98 or, as appropriate, 70% of relative density, Earth Engineering Consultants, Inc. EEC Project No, 1082101 O,ctober 13, 2008 Page 8 After placement of the fill materials, where necessary, care should be taken to avoid excessive wetting or drying of those materials. Bearing materials which are loosened or disturbed by the construction activities or materials which become dry and desiccated or wet and softened should be removed and replaced or reworked in place prior to construction of the overlying improvements. Exterior foundations and foundations in unheated areas should be located at least 30 inches below adjacent exterior grade to provide frost protection. We recommend formed continuous footings have a minimum width of 12 inches and isolated column foundations have a minimum width of 24 inches. Seismic The site soil conditions consist of approximately 30-feet or more of overburden soils overlying presumed moderately hard bedrock. For those site conditions, the 2006 International Building Code indicates a Seismic Site Classification of D. Lateral Earth Pressures A portion of the building may be constructed "below grade" as garden -level construction, and may be subject to lateral earth pressures. Passive lateral earth pressures may help resist the driving forces on foundation walls, retaining wall, or other similar site structures. Active lateral earth pressures could be used for design of structures where some movement of the structure is anticipated, such as retaining walls. The total deflection of structures for design with active earth pressure is estimated to be on the order of one half of one percent of the height of the down slope side of the structure. We recommend at -rest pressures be used for design of structures where rotation of the walls is restrained. Passive pressures and friction between the footing and bearing soils could be used for design of resistance to movement of retaining walls. Earth Engineering Consultants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 9 Coefficient values for backfill with anticipated types of soils for calculation of active, at rest and passive earth pressures are provided in the table below, Equivalent fluid pressure is equal to the coefficient times the appropriate soil unit weight Those coefficient values are based on horizontal backfill with backfill soils consisting of essentially granular materials with a friction angle of a 30 degrees or low volume change cohesive soils. For the at -rest and active earth pressures, slopes away from the structure would result in reduced driving forces with slopes up away from the structures resulting in greater forces on the walls. The passive resistance would be reduced with slopes away from the wall. The top 30-inches of soil on the passive resistance side of walls could be used as a surcharge load; however, should not be used as a part of the passive resistance value. Frictional resistance is, equal to the tangent of the friction angle times the normal force, Soil Type Low Plasticity Cohesive Medium Dense Granular Wet Unit Weight 115 135 . . ........ Saturated Unit Weight 135 . ..... ... ... 140 Friction Angle (0) 150 300 Active Pressure Coefficient O59 0,33 At -rest Pressure Coefficient 034 0,50 Passive Pressure Coefficient 130 100 Surcharge loads or point loads placed in the backfill can also create additional loads on below grade walls. Those situations should be designed on an individual basis. The outlined values do not include factors of safety nor allowances for hydrostatic loads. Care should be taken to develop appropriate drainage systems behind below grade walls to eliminate potential for hydrostatic loads developing on the walls. Those systems would likely include perimeter drain systems extending to sump areas or free outfall where reverse Earth Engineeraig ConsuOants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 10 flow cannot occur into the system. Where necessary, appropriate hydrostatic load values should be used for design, Floor Slabs It is recommended to over-excavate/scarify and re -work the upper 12-inches of the existing subgrade soils prior to placement of new fill or underslab gravel materials. The existing subgrade materials should be scarified or over -excavated a minimum depth of 12-inches; moisture conditioned to ±2 percent of optimum moisture content and mechanically compacted to at least 95% of standard Proctor density. The scarification and re -working of the upper 1-inches will not fully eliminate the possibilities of slab movement; but movements should be reduced and tend to be more uniform. We estimate the long term movement of floor slabs with properly prepared subgrade subsoils as outlined above would be about 1-1 /-inch,. If slab movement cannot be tolerated for the proposed floor slabs, as previously stated, the use of a minimum 2-foot layer of structural fill material placed and compacted beneath the floor slabs should be considered. This procedure will not fully eliminate the possibilities of slab movement; but movements should be reduced and tend to be more uniform, For placement of floor slabs on structural fill material, we suggest a placement of a minimum of 2-feet zone of properly placed and compacted imported structural fill material, such as CDOT Class 5, 6, or 7 aggregate base course material or recycled concrete be used. The approved fill material should be moisture conditioned to +/- 2% of optimum moisture content, place in uniform 9-inch lifts and mechanically compact to at least 95% of standard Proctor density As'rM D698. This procedure will not fully eliminate the possibilities of slab movement; but movements should be reduced and tend to be more uniform. Use of a granular fill material beneath interior floor slabs also requires excellent drainage around the perimeter of the building to minimize the potential for surface infiltration ponding, on the underlying subgrade soils. For garden -level construction an exterior perimeter drainage system should be installed. Emili Engineering Consultants, Inc. EEC Project No. 1082101 October 13, 2008 Page 1.1 Additional floor slab design and construction recommendations are as follows: Positive separations and/or isolationjoints should be provided between slabs and all foundations, columns or utility lines to allow independent movement. Control j oints should be provided in slabs to control the location and extent of cracking. Interior trench backfill placed beneath slabs should be compacted in a similar manner as previously described for imported structural fill material. In areas subjected to normal loading, a minimum 4-inch layer of clean -graded gravel or aggregate base course should be placed beneath interior floor slabs. Floor slabs should not be constructed on frozen subgrade. Other design and construction considerations, as outlined in the ACI Design Manual, Section 302. 1 R are recommended. Pavement and Exterior Flatwork Subgrades/Pavement Design Sections We expect the site pavements will include areas designated for automobile traffic and areas for heavy truck traffic. Heavy duty traffic areas, assume an equivalent daily load axle (EDLA) rating of 15 and automobile areas an EDLA of 7. Proofrolling and recompacting the subgrade is recommended immediately prior to placernent of the aggregate road base section. Soft or weak areas delineated by the proofrolling operations should be undercut or stabilized in -place to achieve the appropriate subgrade support. Based on the subsurface conditions encountered at the site, and the laboratory test results, it is recommended tire on -site Pavement areas be designed using an R-value of 10, based on the soils classifications of the subsoils on -site. Far Fngineering Conoltants, Inc. EEC Project No. 1082101 October 13, 2008 Page 12 S,ubgrade stabilization, for composite pavement section areas, (i.e., hot mix asphalt underlain by aggregate base course), to mitigate for either expansive subgrade conditions as indicated by the swell -index values in excess of 2%, or potentially compressible conditions in isolated areas, (i.e., areas below existing pavement sections), may include incorporation of a chemical treatment such as fly ash to enhance the subgrade integrity. An alternate -would be to over - excavate or "cut to grade" to accommodate a minimum of 2-feet of non -expansive granular soils to be placed and compacted beneath the pavement section. If Portland Cement Concrete (PCQ pavement is being considered as the selected pavement option, subgrade Stabilization at a minimum should include at least 12-inches of scarified, moisture conditioned and recompacted subgrade layer. If the fly ash alternative stabilization approach is selected for use in conjunction with a composite pavement section, EEC recommends incorporating approximately 13% (by weight) Class C fly ash, into the upper 12-inches of subgrade. Hot Mix Asphalt (HMA) underlain by crushed aggregate base course with or without a fly ash treated subgrade, and non -reinforced concrete pavement are feasible alternatives for the proposed on -site paved sections. Pavement design methods are intended to provide structural sections with adequate thickness over a particular subgrade such that wheel loads are reduced to a level the subgrade can support. The support characteristics of the subgrade for pavement design do not account for shrink/swell movements of an expansive clay subgrade or consolidation of a wetted subgrade, Thus, the pavement may be adequate from a structural standpoint, yet still experience cracking and deformation due to shrink/swel I related movement of the subgrade. It is, therefore, important to minimize moisture changes in the subgrade to reduce shrink/swell movements. Recommended pavement sections are provided below in TABLE 1. The hot bituminous pavement (HBP) should be grading, S (75) with PG 58-28 oil. The aggregate base should be Class 5 or Class 6 base. Portland cement concrete should have a minimum 29-day compressive strength of 3500 psi and should be air entrained. HBP pavements may show F,'.'arlh E`nginecring Consultants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 13 rutting and distress in truck loading and turning areas, Concrete pavements should be considered in those areas. TABLE I — RECOMMENDED PAVEMENT SECTIONS Automobile Parking Heavy Duty Areas EDLA 7 25 Reliability 70% 75% Resilient Modulus 3562 3562 PSI Loss 2.5 2.0 .......... . ........ Design Structure Number 2.41 2,76 Composite: Alternative A Hot Biturninous Pavement 411 4-1/2" Aggregate Base 611 7" Design Structure Number (2,42) (175) Composite: Alternative B Hot Biturninous Pavement 3-1/2" 3-1/2" Aggregate Base 41t 6" Fly Asti Treated Subgrade 1215 12 Design Structure Number (2,58) (2.80) PCC (Non -reinforced) "I I'll , . .......... ... . .. . ..5" . ....... . ..... 7 (I) For use of fly ash in the on -site pavement areas for stabilization purposes, it is recommended that at least the upper 12-inches of the prepared subgrade be treated with approximately 13% fly ash (by weight) of Class C fly ash. The recommended pavement sections are minimums and periodic maintenance should be expected. Longitudinal and transverse joints should be provided as needed ill concrete pavements for expansion/contraction and isolation. The location and extent of joints should be based upon, the final pavement geometry, Sawed joints should be cut within 24-hours of concrete placement. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer, Earth 1"Inginecring Consultants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 14 Since the cohesive soils on the site have some shrink1consolidation potential, pavementscould crack in the future primarily because of the volume change of the soils when subjected to an increase in moisture content to the subgrade. The cracking, while not desirable, does not necessarily constitute structural failure of the pavement. The collection and diversion of surface drainage away from paved areas is critical to the satisfactory performance of the pavement. Drainage design should provide for the removal of water from paved areas in order to reduce the potential for wetting of the subgrade soils. Long-term pavement performance will be dependent upon several factors, including maintaining subgrade moisture levels and providing for preventive maintenance. The following recommendations, should be considered the minimum: a, The subgrade and the pavement surface should be adequately sloped to promote proper surface drainage. o Install pavement drainage surrounding areas anticipated for frequent wetting (e.g. garden centers, wash racks) 0 Install joint sealant and seal cracks immediately, • Seal all landscaped areas in, or adjacent to pavements to minimize or prevent moisture migration to subgrade soils; • Placing compacted, low permeability back fill against the exterior side of curb and gutter; and, o Placing curb, gutter, and/or sidewalk directly on approved proof rolled subgrade soils with the use of base course materials. Preventive maintenance should be planned and provided for through an on -going pavement management program. Preventive maintenance activities are intended to slow the rate of pavement deterioration, and to preserve the pavement investment, Preventive maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface scaling). Preventive maintenance is usually the first priority when implernenting, a planned pavement maintenance program and provides the highest return on Farlh Engimering Consultants, Inc EEC Project No. 1082 101 October 13, 2008 Page 15 investment for pavements. Prior to implementing any maintenance, additional engineering observation is recommended to determine the type and extent of preventive maintenance. Site grading is generally accomplished early in the construction phase. However as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. The subgrade should be carefully evaluated at the time of pavement construction for signs of disturbance, rutting, or excessive drying, If disturbance has occurred, pavement subgrade areas should be reworked, moisture conditioned, and properly compacted to the recommendations in this report immediately prior Please note that if during or after placement of the stabilization or initial lift of pavernent, the area is observed to be yielding under vehicle traffic or construction equipment, it is recommended that EEC be contacted for additional alternative methods of stabilization, or a change in the pavement section. Other Considerations Positive drainage should be developed away from the structure and pavement areas with a minimum slope of I -inch per foot for the first 10-feet away from the improvements in landscape areas. Care should be taken in planning of landscaping adjacent to the building and parking and drive areas to avoid features which would pond water adjacent to the pavement, foundations or stem wal Is. Placement of plants which require irrigation systems or could result in fluctuations of the moisture content of the subgrade material should be avoided adjacent to site improvements. Lawn watering systems should not be placed within 5 feet of the perimeter of the building. Spray heads should be designed not to spray water on or immediately adjacent to the structure or site pavements. Roof drains should be designed to discharge at least 5 feet away from the structure and away from the pavement areas. Egrth Engineering Consultants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 16 Excavations into the on -site soils may encounter a variety of conditions. Excavations into the on -site clays can be expected to stand on relatively steep temporary slopes during construction. However, if excavations, extend into the underlying granular strata, caving soils may be encountered. The individual contractor(s) should be made responsible for designing and constructing stable, temporary excavations as required to maintain stability of both the excavation sides and bottom. All excavations should be sloped or shored in the interest of safety following local and federal regulations, including current OSHA excavation and trench safety standards. GENERAL COMMENTS The analysis and recommendations presented in this report are based upon the data obtained from the soil borings performed at the indicated locations and from any other information discussed in this report. This report does not reflect any variations, which may occur between borings or across the site. The nature and extent of such variations may not become evident until construction. If variations appear evident, it will be necessary to re-evaluate the recommendations of this report, It is recommended that the geotechnical engineer be retained to review the plans and specifications so comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. It is further recommended that the geotechnical engineer be retained for testing and observations during carthwork phases to help determine that the design requirements are fulfilled. Site -specific explorations should be completed to develop site -specific recommendations, for each of the site buildings. This report has been prepared for the exclusive use of Everitt Companies, for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranty, express or implied, is made. In the event that any changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be Earth Engineering Consultants, Inc. EEC Project No. 1082 101 October 13, 2008 Page 17 considered valid unless the changes are reviewed and the conclusions of this report are modified or verified in writing by the geotechnical engineer. DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS SS,: Split Spoon - 13/8" LD,, 2" O.D, unless otherwise noted PS: Piston Sample ST: Thin-WalledTube - 2" O.D., unless otherwise noted WS: Wash Sample R: Ring Barrel Sampler - 2.42"' I.D., 3" O.D. unless otherwise noted PA: Power Auger FT: Fish Tail Bit HA: Hand Auger RB: Rock Bit DB: Diamond Bit = 4", N, B BS: Bulk Sample AS: Auger Sample PM: Pressure Meter HS: Hollow Stem Auger WB: Wash Bore Standard "N" Penetration: Blows ,per foot of a 140 pound hammer failing 30 inches on a 2-inch O�.D. split spoon, except where noted. WATER LEVEL MEASUREMENT SYMBOLS WL : Water Level WS :'"While Sampling WCI: Wet Cave in WD: While Drilling DCL Dry Cave in BCR.- Before Casing Removal AB : After Boring ACR: After Casting Removal Water levels indicated on ffie boring logs are the levels measured in the borings at the time indicated. in pervious soils, the indicated levels, may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not possible with only short term observations. DESCRIPTIVE SOIL CLASSIFICATION Soil Classification is based on the Unified Soil Classification system and the ASTM Designations D-2488. Coarse Grained Soils have move than 50% of their dry weight retained on a #20�0 sieve; they are described as: boulders, cobbles, gravel or sand, Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are 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 relative in -place density and fine grained soils on the basis of their consistency. Example: Lean clay with sand, trace gravel, stiff (CL); silty sand, trace gravel, medium dense (SM). CONSISTENCY OF FINE-GRAINED SOILS Unconfined Compressive Strength, Qu, psf Consistency < 500 Very Soft 500- 1,000 Soft 1,001 - 2,000 Medium 2,001 - 4,000 stiff 4,001 - 8,000 Very Stiff 8,001 - 16,000 Very Hard RELATIVE DENSITY OF COARSE -GRAINED SOILS N-Blows/ft Relative Density 0-3 Very Loose 4-9 Loose 10-29 Medium Dense 30-49 Dense 50-80 Very Dense 80+ Extremely Dense PHYSICAL PROPERTIES OF BEDROCK DEGREE, OF WEATHERING: slight Slight decomposition of parent material on joints. May be color change. Moderate Some decomposition and color change throughout. High Rock highly decomposed, may be extremely broken, HARDNESS AND DEGREE OF CEMENTATION-. Limestone and Dolomite: ff',_ir_ffi'ffilii_1tto scratch with knife, Moderately Can be scratched easily with knife. [lard Cannot be scratched with fingernail. Soft Can be scratched with fingernail. �e,,Siltstone and_Qgyqo_Li_e: Hard Can be scratched easily with knife, cannot be scratched with fingernail. Moderately Can be scratched with fingernail. Hard soft Can be easily dented but not molded with fingers, Sandstone and_Cqn&Wmerate: Well Capable of scratching a knife blade. Cemented Cemented Can be: scratched with knife. Poorly Can be broken apart easily with fingers. Cemented UNIFIED SOIL ULASSIRCAITON SYSTEM Criteria tar Asnigning Grasp Syrnbals and Group names Using laborotary tests Coarse—Groined Grovels mare than Clean Grovels Less Soils more than 507 of coarse than 5% fines C(j>4 and <Qc,0E 50% retained an iraction, retained No. 200 sieve on No. 4 sieve Cu <4 and/or 1>Cc>3r' Grovels with Fines Fines classify as ML or MH more than 12% fines Fines classify as CL or CH Sands 50% or Clean Sands Less Cu>5 and 1<c<_3' more coarse than 5fines reaction posses Cu �15 andlor 1>Cc>34 No. 4 sieve Sands with Fines Fines classify as ML or MH more than 12% fines Fines classify as CL or CIA Soil Clossification Group Group Name Symbol GW Well -graded groveC' GP Poorly -graded gravel' GM Silty gravel, G,H GC Clayey Gravel SW Welf-groded sand' SP Poorty-graded sand' Sm Silty sand"' SC Clayey scinid'40 Fine-Gral�ned Silts and Clays inorganic PW and plats on or above WILine' CL Leon cloy Snits 513% 10T Liquid Umli leads . ....... . _ more posses the than 50 R<4 or plots below 'A"Line' ML 5 R It No. 200 sieve organic Liquid Limit - oven dried Organic clay <0.75 OL Liquid Limit - not dried Organic silt"," Silts and Clays inorganic lal plots on or above 'A'Une CH Fat cloy Liquid Limit 50 or more PI plots below 'A'Une MIA Elastic Sllt'uy organic Liquid Limit - oven dried Organic cloy' <0. 75 OH - Liquid Limit - not dried Organic silt"' Highly organic sails Primarily organic matter, dark in color, and organic odor PT Peat "Elosed on the material passing the 3-6, (75- C CU-Q,/D,Cc- Lqj� 'If sag contains 15 to 2 slus No, 20(% add *with 'wlth mm) sieve sand' aw qrovel*, whichever Is Nt yield sample contolned cobbles or bouldff�s, predominant. of both, add "with cobbres or boulders. or both* i,if soil contains k 30* plus No. 200 to group nam,m "If sal contains 215% send. add*wlth -sond*to predominantly sarid, add 'sandy to group 'Grovels with 5 to 12X fines required dual myludoltz GW_C3A well graded gravel with silt group Rwne� elffines classify as CL-W_ use dual SyrnWl A -L �lf so# contains Z 30% plus No. 20f1 predominantly gravel, add 'gravely" to group GW-QC wall -graded gravel with day GP -GM poorly -graded qrr�d with silk Gc-cm, or sc-sm, v fines e- orgonlo, -dd'wlth organic fi,,Wto nQ`M1% p'z4 and plots on or above W line. 'GP -GC poorly -graded gravel with cloy 'Sands with 5 to 1= Ones require dud group name Itf Bull cantolns At ravel, c0d'with gravel' 'P�o 6r plots below W line. 'Ptl plots on or above W Pine. Aymbeft. SW -.did -ell-graded sand with silk In group, narine. ' if Aharb" flirits Plots shaded arra� sag pad opt Plots below A'" Me. SW -SC well --graded sand with cloy CL-MIL, ritty day, IV-SM poorly graded sand with sift SP-SC poorly graded sand with day all For COSWnW.Clon Me-groincd As d Ar--V"0in,4 Wractla. .) 9miried *04. tou.&- M W-lln . lWxWtW_.1 M-1, to U.-I" U F1 CL73 (U.-20l E..tion so V-%,. W.Almal M U-16 to P1.1 than PI-11-9 (LL-6) 30- wr .7- t Ln V - MH 01as wi-oppWL all OD �::] a 70 an so .vas LIQUO UMIT iALL} 9 w .c q .`0 2 4 �, '�,col LU m C) I 0 � I 0 .` :.' ILu fro, LU CJ (D LUZ LU 0 0 0 �j u M uj +w a W, sw 0 a� 4�> I Jr 1 uii L ,auio ' LU �µ n w" EVERF'rr CATTRACTS A & C FORT COLLINS, COLOR ADO EEC PROJEC,r No. 1082 101 SEFFEMBER 2008 -EEC, .... . ...... CENTRE FOR ADVANCED TECHNOLOGIES - 7TH FILING, TRACTS A & C FORT COLLINS, COLORADO PROJECT NO,. 1082101 DATE. SEPTEMBER2008 LOG OF BORING B.1 (PIEZOMETER) RIG YPII CME45 SHEET I OF 1 WATER DEPTH FOREMAN: DO START DATE 9J2212008 WHILE DRILLING 13.5' AUGER TYPE; VCFA FINISH DATE 912212008 9i'3012008 14.6' SPTHAMMERt MANUAL SURFACE ELEV N(A 24 HOUR NIA SOIL DESCRIPTION 0 N QU mc Do A4JMITS -200 SWELL. (SLOI (PSFI PAESSURF TOPSPOIL & VEGETATION SANDY LEAN CLAY (CL) I CLAYEY SAND (SC) brown J red 2 medwim aW to siff i medium dense 3 4 CS -5 7 3600 ........... 18.3 106.2 33 14 49.3 <500 of None 6 7 8 9 SS 10 -- 2500 - mg -- 12 13 14 CS, 16 11 4000 19.1 1019.4 BOTTOM OF BORING DEPTH 15 D 16 17 lei 19 20 2!1 22 23 24 25 Earth Engineering Consultants, CENTRE IFCR ADVANCED TECHNOLOGIES - 7TH FILING, TRACTS A & C FORT COLLINS, COLORADO PROJECTNIOID82101 DATE: SEPTEMBER2008 LOG OF BORING B-2 IPIF-ZOMETE;) MG YPE: CME45 SHEET I OF 2 WATER DEPTH FOREMAN: DO START DATE 9122J2000 WHILE DRILLING AUGER TYPE: 4" CFA FINISH DATE 912W2008 9134W2000 SPT HAMMER*, MANUAL SURFACE ELEV NIA 24 HOUR NIA SOIL DESCRIPTION D N QU ME 00 A�UN"S -2W SWELL LL � Pt TYPE —12—LOWS1111) IPSFI (PtF) I%� PRESSURE I %a $00 PSF TOPSOIL & VEGETATION 1 LEAN CLAY (CL) brown 2 sfiff to very stiff 14 "'o 9.7 99A 39 1� 21 88.2 3500 psf 3 .7% 4 Lm l scattered graveISS 6 24 0000+ 10"4 7_ SILTY SAND with GRAVEL CS: 10 24 lan I gray/ rust, madi um dense 11 12 13 14 CLAYEY SAND with GRAVEL (SC) brown I red SS is 6 1000 22.5 medium dense 16 1!7 18 19 Ecs -20- a I SDD 18A 10S.7 - 21- 22 2'3 24 SS 26 14 2000 23.9 Continued on Sheet 2 of 2 Earth Engineering Consultants CENTRE FOR ADVANCED TECHNOLOGIES - 7TH FILING, TRACTS A & C FORT COLLINS, COLORADO PROJECT NO, 10821011 GATE: LOG OF BORING ia•2 �PirmzOMETER _SEPTEMBER2008 RIG TYPE; CME45 SHEET 2 OF 2 WATER DEPTH FOREMAN: DG START DATE W22J2009 WHILE DRILLING 1 &01 AUGER TYPE! 4" CFA FINISH DATE 9i2=008 9130=08 15.51 SPT HAMMER: MANUAL SURFACE ELEV N/A 24 HOUR N/A SOIL DESCRIPTION 0 N ou MIC 00 A4jMFt$ .20o SWELL LL Pi TYPE 2mL. caLowwFT) JPSFJ 4Yk1 (PCF) I4EI PRESSURE Continued From Sheel 1 of 2 26 CLAYEY $AND wiIh GRAVEL (SC) 27 brown 1red medium dense le dense 28 25 SS 30 13 2600 24.6 BOTTOM OF BORING DEPTH 30 5' 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48, 49 50 Earth Engineering Consul nts CENTRE FOR ADVANCED TECHNOLOGIES - 7TH FILING, TRACTS A & C FORT COLLINS, COLORADO PRGJECTNO^.1082101 7- DATE; SEFTEMBeil LOG OF BORING 84 JPIEZOMETER) RIG TYPE. CM946 SHEET I OF 2 WATER I WATER DEPTH FOREMAN:DG START DATE W22/2000 WHILE DRILLING 17.01 AUGER TYPE: W'CFA FINISH DATE 9122J2008 9 W13012008 16,4' SPT HAMMEk MANUAL SURFACE IELEV N/A 24 MOU WR NIA SOIL DESCRIPTION D N QU Mc DO A,UM473 -200 $WELL F'-rYPr. (FtETI JOLOW&I"r), IPSF) M (pcf) LL I%) PRESSURE % W PSF TOPSOIL & VEGETATION 7- LEAN CLAY lCL) brown 2 spill lo very strff with calcareous deposits 9000+ 10.2 100.4 2000 of 3.2% 4 SANDY LEAN CLAY (CL) t SS 6 14 71 red A brown medium stiff to stiff 6 Intermittent gravel tanses 7 9 [Cs -10- 22 9000+ 2,6 123.0 11 12 $3 - 14 CLAYEY SAND with GRAVEL (SC) red t brown SS Is 9 Soo 24.9 medium dense - - 16 17 Ecs 20 6 Soo 1 26.4 101.6 21 22 23 24 SS 25 9 1000 30.0, 1 Continued on Sheet 2 of 2 Earth Engineering Consultants CENTRE FOR ADVANCED TECHNOLOGIES - YTH FILING, TRACTS A. & C FORT COLLINS, COLORADO PROJECT NO1082101 DATE: SE,PTEMRER 2008 LOG OF GORING e•3 PIEZOMETER RIG TYPE: CME45 SHEET 2 OF 2 WATER DEPTHI FOREMAN: OG START CAFE I 9122A2006 WHILE DRILLING 17.0" AUGER TYPE; 4"CFA FINISH DATE '! 9122/2008 8J301200.8 16.4' SPT HAMMER: M'ANUA1 SURFACE EL.EV NIA 24 HOUR NIA SOIL DESCRIPTION tr N Qu any ¢re n-t.IIVITS 200 $WELL LL PI TYPE IFEET} OLOWS)FTI �IPE'FV r i 1PCFp I%j PRE86UR15. Mr nF'{I PBF Continued tram Sheet 11 of 2 26 CLAYEY SAND vrnth GRAVEL (SC) 27 red, medium dense 20 29 SS 30 12 4008 23.8 BOTTOM OF BORING DEPTH '30 5 mm31 32 33 _34. 36 38. 37 36 39 40 I W _41 42 43 44 46 46 47 48 49 60 Earth Engineering Consultants CENTRE FOR ADVANCED TECHNOLOGIES - R"T'H FILING, TRACTS A & FORT" COLLINS, COLORADO PROJECT NO: 1082101 DATE: SEPTEMBER 2008 LOG OF BORING B-4 RIG TYPE, GME48 SHEET 1 OF 1 WATER. DEPTH FOREMAW GG START GATE, 912212008 WHILE GRILLING None AUGER TYPE: 4- CFA FI NISH GATE W22+2009 AFTER GRILLING NIA SPT HAMMER, MANUAL SURFACE ELEV WA 24 HOUR NIA SOIL DESCRIPTION D II ov MC 00 A -LIMITS a $WELL TYPE FEETI (BLCVIM$iF"p"M q,PSFy _V'Y6Y ('PCFI LL PI I r1iFs8uRE &Cl4M PSF TOPSOIL. & VEGETATION 1 LEAN CLAY (,CL) Ibrown 2'. skull to very SIM w101 calcareous deposals 3 4 CS 5 18 9000+ 11.4 99.9 38 20 88.0 500 si 1.1 E m7_ S 5 CLAYEY SAND w1h GRAVEL (SC) SS 10 8 &9 real I medium dense � 1® rot 13 14 SS 1s 9 19.II BOTTOM OF BORING DEPTH 15.5" 16 17 18 19 20 21 22 23 24 25 Earth Engineering Consultants Material Description: Sandy Lean Clay (CL) / Clayey Sand (SC) Sample Location: Boring 1, Sample 1, Depth 4' Liquid Limit: 33 1Plasticity Index: 14 Passing #200: 493% Beginning Moisture: 18.3% Dry Density: 111.4 p,sf JEnding Moisture: 173% Swell Pressure: <500 psf 1°In S eNN 800: None 10.0 8.0 ........... 6,0 4,0 2,1 > a 0.0 -2.0 "Aat r Added -4,0 1 1- 1 1 H i-+-- C 0 -6.0 0 0 0 -Mo 0.01 01 1 10 Load(TSF) Project: Centre for Advanced Technology - 7th Filing 7th Filing, Tracts A & C Project #: 1082101 Date: September 2008 EEC C- I E I:Material Description: Lean Clay (CL) [Sample Location: Boring 2, Sample 1, Depth 2' Liquid Limit: 39; JPlasticity Index: 2 1 % Passing #200: 88.2% Beginning Moisture:- 92% 1 i �Dry Density: 10&4 psf Ending Moisturei 23.0% ISwell Pressure: 3500 psf 1% Swell: @ 500: 33% A^ ^ Project: Centre for Advanced Technology - 7th Filing 7th Filing, Tracts A & C Project #: 1082101 Date: September 2008 EE,l Material Description- .. ............. . . . . . .......... Birown Lean Clay (CL) . ............. ,Sample Location-, . . ....... . ..... Boring 3, Sample 1, Depth Z Liquid Urnit Plasticity index: - - ------- '%Passing #2.00: .......... 1% Swell @ 500: 3.2% 0.01 0.1 1 10 Load(TSF) Project, Centre for Advanced Technology - 7th Filing 7th Filing, Tracts A & C Project #: 1082101 Date: September 2008 SEC ................................ . . Material Description: ................. . . . ......... Brown Lean Clay (CL) $ample Location: Boring 4, Sample 1, Depth 4' Liquid Limit: 38 Plasticity Index 20 ... . . ...... ..... . % Passing #200: 88.0% Beginning Moisture: 10,9% MRIN -1 $well Pressure: 500 psf . . . .............. .......................... - % Swell @ 500: 11%__ Project: Centre for Advanced Technology - 7th Filing 7th Filing, Tracts A & C Project 1082101 Date: September 2008