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Home My WebLink AboutBLOOM FILING SIX - PDP230017 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTPRELIMINARY SUBSURFACE EXPLORATION REPORT PROPOSED MULBERRY STREET MIXED-USE DEVELOPMENT NORTH SIDE OF MULBERRY STREET AND WEST OF NORTH I-25 FRONTAGE ROAD FORT COLLINS, COLORADO EEC PROJECT NO. 1232071 Prepared for: TDC-Development Address: Attn: Mr. Dean Barber (dbarber@tdc-dev.com) Earth Engineering Consultants, LLC 4396 Greenfield Drive Windsor, Colorado 80550 4396 G REENF IELD D RIVE W I N DSOR, COLORADO 80550 (970) 5 4 5 -3908 F AX (970) 663-0282 October 10, 2023 TDC-Development Address: Attn: Mr. Dean Barber (dbarber@tdc-dev.com) Re: Preliminary Subsurface Exploration Report Proposed Mulberry Street Mixed-Use Development North side of Mulberry Street and West of North I-25 Frontage Road Fort Collins, Colorado EEC Project No. 1232071 Mr. Barber: Enclosed, herewith, are the results of the preliminary subsurface exploration completed by Earth Engineering Consultants, LLC (EEC) for the proposed Mulberry Street mixed-use development planned for design and construction at the north side of Mulberry Street and west of North I-25 Frontage Road in Fort Collins, Colorado. For this exploration, EEC personnel advanced four (4) preliminary soil borings to depths of approximately 20 to 25 feet below present site grades at pre- selected locations within the various proposed building footprints and associated on-site pavement improvements. This exploration was completed in general accordance with our proposal dated August 4, 2023. In summary, the subsurface conditions encountered beneath the surficial vegetation/topsoil generally consisted of 8 to 12 feet of cohesive to slightly cohesive sandy lean clay to clayey-silty sand soils extending to the underlying granular soils. The cohesive soils were generally moist, soft / loose to very stiff / dense and exhibited nil to low swell potential with slight tendency to hydro-compact at current moisture and density conditions. Sand/gravel with intermittent clay zones were encountered below the cohesive to slightly cohesive soils and extended to the depths explored; approximately 20 to 25 feet below the ground. Sand with clay and gravel soils were generally moist and were loose to dense. Groundwater was observed in all of the borings at depths of approximately 8 to 12 feet below the ground surface. Based on the encountered subsurface conditions and anticipated maximum wall and column loads on the order of 1 to 3 klf and 25 to 100 kips, respectively, in our opinion, the proposed retail / mixed-use development structures could be supported on conventional spread footings bearing on approved undisturbed overburden subsoils and/or approved engineered fill material. Pavements, interior floor slabs, and exterior flatwork could be supported on a zone of scarified and moisture conditioned on-site PRELIMINARY SUBSURFACE EXPLORATION REPORT PROPOSED MULBERRY STREET MIXED-USE DEVELOPMENT NORTH SIDE OF MULBERRY STREET AND WEST OF NORTH I-25 FRONTAGE ROAD FORT COLLINS, COLORADO EEC PROJECT NO. 1232071 October 10, 2023 INTRODUCTION The preliminary subsurface exploration for the proposed mixed-use development planned for design and construction at the north side of Mulberry Street and west of North Interstate 25 (I-25) in Fort Collins, Colorado, has been completed. For this preliminary exploration, Earth Engineering Consultants, LLC (EEC) advanced four (4) preliminary soil borings to depths of approximately 20 to 25 feet below present site grades at pre-selected locations within the various building footprints and associated on-site pavement improvement areas, as presented on the enclosed site plan. Upon completion of the drilling operations, the four (4) open bore holes were converted to temporary PVC cased piezometers. Individual preliminary boring logs and the enclosed site plan indicating the approximate boring locations are included with this report. This exploration was completed in general accordance with our proposal dated August 4, 2023. We understand the master plan concept for this proposed development will include mixed-use retail/commercial along with on-site pavement improvements as depicted on the enclosed site plan provided to us by TDC on July 31, 2023. Foundation loads are estimated to be light with maximum continuous wall loads on the order of approximately 1 to 3 kips per linear foot (KLF) and maximum column loads on the order of approximately 25 to 100 kips. Floor loads are expected to be light to moderate. If actual loads exceed those assumed herein or if basement construction is being considered for the site, we should be consulted to review and modify the recommendations accordingly, if necessary. The pavements are expected to include areas for light duty automobile traffic as well as areas for heavier duty traffic. Small grade changes, cuts and fills less than 4 feet (+/-), are expected to develop site grades for the proposed development. The purpose of this report is to describe 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 interior floor slabs, exterior flatwork, and design of pavements for the proposed development. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 2 EXPLORATION AND TESTING PROCEDURES The boring locations were established in the field by representatives from EEC by pacing and estimating angles from identifiable site features with the aid of a hand-held GPS unit using appropriate Google Earth coordinates. Those approximate boring locations are indicated on the attached boring location diagram. The locations of the borings should be considered accurate only to the degree implied by the methods used to make the field measurements. The borings were performed using a truck-mounted CME-55 drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced using 4-inch nominal diameter continuous flight augers. After completion of the drilling operations, temporary PVC/piezometer pipe was installed in the four (4) preliminary borings for supplemental groundwater measurement purposes. These PVC casings were removed upon readings approximately 2 weeks after drilling. Samples of the subsurface materials encountered were obtained using split-barrel and California barrel sampling procedures in general accordance with ASTM Specifications D1586 and D3550, respectively. In the split-barrel and California barrel sampling procedures, standard sampling spoons are advanced into the ground with a 140-pound hammer falling 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 cohesionless soils and, to a lesser degree of accuracy, the consistency of cohesive soils and hardness of weathered bedrock. In the California barrel sampling procedure, relatively intact samples are obtained in removable brass liners. All samples obtained in the field were sealed and returned to our laboratory for further examination, classification, and testing. Laboratory moisture content tests were completed on each of the recovered samples. Atterberg limits and washed sieve analysis tests were completed on select samples to evaluate the quantity and plasticity of fines in the subgrade samples. Swell/consolidation tests were completed on selected samples to evaluate the potential for the subgrade materials to change volume with variation in moisture and load. A water-soluble sulfate test was completed on a select sample to evaluate potential adverse reactions to site-cast concrete. 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 general 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 Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 3 Classification System is indicated on the boring logs and a brief description of that classification system is included with this report. SITE AND SUBSURFACE CONDITIONS The proposed retail/mixed-use development planned for design and construction is located om the north side of Mulberry Street and west of North I-25 Frontage Road. The project site is a vacant lot that has previously been used for agricultural purposes. The cursory review of the historic Google Earth imagery indicates minor stripping/earthwork/leveling operations after circa 2019. Sparse vegetation and topsoil were encountered at the surface of each preliminary test boring. The relief across is the site is approximately estimated to be on the order of 8 feet. Photographs of the site taken at time of our drilling are provided with this report. EEC field personnel were on site during drilling to evaluate the subsurface conditions encountered and direct the drilling activities. Field logs prepared by EEC site personnel were based on visual and tactual observation of disturbed samples and auger cuttings. The final boring logs included with this report may contain modifications to the field logs based on results of laboratory testing and evaluation. Based on results of the field borings and laboratory testing, subsurface conditions can be generalized as follows. The subsurface soils encountered beneath surficial vegetation/topsoil, generally consisted of 8 to 12 feet of cohesive to slightly cohesive sandy lean clay to clayey-silty sand soils extending to the underlying granular soils. The cohesive soils were generally moist, soft / loose to very stiff / dense and exhibited nil to low swell potential with slight tendency to hydro-compact at current moisture and density conditions. Sand/gravel with intermittent clay zones were encountered below the cohesive to slightly cohesive soils and were extended to the depths explored; approximately 20 to 25 feet below the ground. Sand with clay and gravel soils were generally moist and were loose to dense. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil and bedrock types. In-situ, the transition of materials may be gradual and indistinct. GROUNDWATER CONDITIONS Observations were made while drilling and on October 2, 2023, within the installed temporary piezometers, to detect the presence and level of groundwater. At the time of drilling and on October 2, 2023, groundwater was observed in the preliminary test borings at depths ranging from Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 4 approximately 8 to 12 feet below existing site grades. The measured depths to groundwater are recorded near the upper right-hand corner of each boring log included with this report. The borings were backfilled after drilling / upon the follow up measurements on October 2, 2023, therefore subsequent groundwater measurements were not possible. The groundwater measurements provided with this report are indicative of groundwater levels at the location and at the time the measurements were completed. Perched and/or trapped water may be encountered in more permeable zones in the subgrade soils at times throughout the year. Perched water is commonly encountered in soils immediately overlying less permeable bedrock materials. Fluctuations in ground water levels and in the location and amount of perched water may occur over time depending on variations in hydrologic conditions, irrigation activities on surrounding properties and other conditions not apparent at the time of this report. ANALYSIS AND RECOMMENDATIONS Swell – Consolidation Test Results The swell-consolidation test is performed to evaluate the swell or collapse potential of soils or bedrock to help determine foundation, floor slab, and pavement design criteria. In this test, relatively intact samples obtained directly from the California barrel sampler are placed in a laboratory apparatus and inundated with water under a predetermined load. All inundated samples are monitored for swell and consolidation. The swell-index is the resulting amount of swell or collapse after inundation, expressed as a percent of the sample’s initial thickness. After the initial inundation period, additional incremental loads are applied to evaluate the swell pressure and consolidation. For this assessment, we conducted five (5) swell-consolidation tests on samples recovered from various intervals/depths. The swell index values for the in-situ soil samples analyzed revealed low to moderate swell characteristics as indicated on the attached swell test summaries. The (+) test results indicate the soil materials swell potential characteristics while the (-) test results indicate the soils materials collapse potential characteristics when inundated with water. The following table summarizes the swell-consolidation laboratory test results for samples obtained during our field explorations for the subject site. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 5 Table I – Laboratory Swell-Consolidation Test Results No of Samples Tested Pre-Load / Inundation Pressure, PSF Description of Material In-Situ Characteristics Range of Swell – Index Test Results Range of Moisture Contents, % Range of Dry Densities, PCF Low End, % High End, % Low End, PCF High End, PCF Low End (+/-) % High End, (+/-) % 5 500 Sandy Lean Clay CL) or Clayey-Silty Sand (SC-SM) 10.8 26.7 94.1 119.3 (-) 0.5 0.0 Colorado Association of Geotechnical Engineers (CAGE) uses the following information presented below to provide uniformity in terminology between geotechnical engineers to provide a relative correlation of performance risk to measured swell. “The representative percent swell values are not necessarily measured values; rather, they are a judgment of the swell of the soil and/or bedrock profile likely to influence slab performance.” Geotechnical engineers use this information to also evaluate the swell potential risks for foundation performance based on the risk categories. Table II - Recommended Representative Swell Potential Descriptions and Corresponding Slab Performance Risk Categories Slab Performance Risk Category Representative Percent Swell (500 psf Surcharge) Representative Percent Swell (1000 psf Surcharge) Low 0 to < 3 0 < 2 Moderate 3 to < 5 2 to < 4 High 5 to < 8 4 to < 6 Very High > 8 > 6 Based on the laboratory test results, the swell/consolidation samples analyzed for this project at current moisture contents and dry densities conditions were generally within nil to low swell range and showed a slight tendency to hydro-compact when inundated with water. General Considerations General guidelines are provided below for the site subgrade preparation. However, it should be noted that compaction and moisture requirements vary between builders and, consequently, between geotechnical engineering companies. If the development lots will be marketed to a target group of builders, fill placement criteria should be obtained from those builders and/or their geotechnical engineering consultants prior to beginning earthwork activities on the site. Representatives from those entities should verify that the fill is being placed consistent with the home builders’ guidelines. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 6 Based on our field and laboratory testing information, the overburden soils on this lot include approximately 8 to 12 feet of sandy lean clay to clayey-silty sand soils overlying gravel/sand soils. Low swell potential was exhibited by the near surface clay samples; however, soft/compressible soils were encountered at locations across the site at varying depths which requires special attention depending on the final site grades and extension of the cut/fill operations. Groundwater was observed at depths of 8 and 12 feet below the ground surface in the borings. We suggest that floor slab subgrade(s) be placed a minimum of 4 feet above the maximum anticipated rise in groundwater levels. If final site grading consists of cuts extending floor slabs to less than 4 feet above the maximum anticipated rise in groundwater, consideration could be given to designing and installing a perimeter drainage system or to elevating/raising the site grades to establish the minimum required 4-foot separation to the maximum anticipated rise in groundwater. Site Preparation All existing vegetation and/or topsoil should be removed from beneath site fills, roadways or building subgrade areas. Stripping depths should be expected to vary, depending on current surface elevations. In addition, any soft/loose native soils, or any existing fill materials without documentation of controlled fill placement should be removed from improvement and/or new fill areas. After stripping and completing all cuts and prior to placement of any fill, floor slabs or pavements, we recommend the exposed soils be scarified to a minimum depth of 9 inches, adjusted in moisture content and compacted to at least 95% of the material's maximum dry density as determined in accordance with ASTM Specification D698, the standard Proctor procedure. The moisture content of the scarified materials should be adjusted to be within a range of ±2% of standard Proctor optimum moisture at the time of compaction. In general, fill materials required to develop the building areas or site pavement subgrades should consist of approved, low-volume change materials which are free from organic matter and debris. The near surface sandy lean clay to clayey-silty sand soils could be used as fill in these areas. We recommend the fill soils be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted to at least 95% of the material’s maximum dry density as determined in accordance with the standard Proctor procedure. The moisture content of predominately clay soils should be adjusted to be within the range of ±2% of optimum moisture content at the time of placement. Granular soil should be adjusted to a workable moisture content. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 7 Specific explorations should be completed for each building lot to develop recommendations specific to the proposed structure and owner/builder and for specific pavement sections. The preliminary recommendations provided in this report are, by necessity, general in nature and would be superseded by site specific explorations/recommendations. Foundation Systems – General Considerations Based on the soils observed at the test boring locations, we believe the buildings could be supported on conventional footing foundations bearing on approved in-situ site soils or on a zone of approved placed and compacted fill material prepared as outlined above. Footings bearing on approved in-situ native soils or on approved engineered fill material placed and compacted as described above could be designed for a maximum net allowable total load soil bearing pressure ranging between 1,500 to 2,500 psf. A minimum dead load pressure would not be required. The net bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure. Total load includes full dead load and live load conditions. After completing a site-specific/lot-specific geotechnical exploration study, a thorough “open- hole/foundation excavation” observation should be performed prior to foundation formwork placement to verify the suitability of the in-place soils and determine the extent of any possible over excavation and replacement procedures, if necessary. After placement of the fill materials, for foundation support, care should be taken to avoid 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 16 inches and isolated column foundations have a minimum width of 30 inches. We estimate the total long-term settlement of footings designed as outlined above would be about 1- inch. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 8 Preliminary Floor Slab/Exterior Flatwork Subgrades We recommend all existing vegetation/topsoil be removed from beneath the floor slab and exterior flatwork areas as previously outlined. After stripping and completing all cuts and prior to placement of any flatwork concrete or fill, the exposed subgrades should be scarified, adjusted in moisture content and compacted. If the subgrades become dry and desiccated prior to floor slab construction, it may be necessary to rework the subgrades prior to floor slab placement. Fill soils required to develop the floor slab subgrades should consist of approved, low-volume change materials which are free from organic matter and debris. Those fill materials should be placed as previously outlined and surcharged/preloaded and/or monitored as necessary to limit total and differential movement after construction of overlying improvements. Preliminary Basement Design and Construction Groundwater was encountered across the site within the preliminary soil borings at approximate depths of 8 to 12 feet below existing site grades. If lower-level construction for either garden-level or full-depth basements is being considered for the site, we would suggest that the lower-level subgrade(s) be placed a minimum of 4 feet above maximum anticipated rise in groundwater levels, or a combination exterior and interior perimeter drainage system(s) be installed. Consideration could be given to 1) either designing and installing an area underdrain system to lower the groundwater levels provided a gravity discharge point can be established. If a gravity outlet/system cannot be designed another consideration would be to design and install a mechanical sump pump system to discharge the collected groundwater within the underdrain system, or 2) elevate/raise the site grades to establish the minimum required four (4) foot separation to the maximum anticipated rise in groundwater. EEC is available to assist in the underdrain design if requested. The following information should also be considered, as previously mentioned, would be to install an interior and exterior perimeter drainage system for each individual residence. To reduce the potential for groundwater to enter the lower level/basement area of the structure(s), installation of a dewatering system is recommended. The dewatering system should, at a minimum, include an under-slab gravel drainage layer sloped to an interior perimeter drainage system. The following provides preliminary design recommendations for interior and exterior perimeter drainage systems. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 9 The under-slab drainage system should consist of a properly sized perforated pipe, embedded in free- draining gravel, placed in a trench at least 12 inches in width. The trench should be inset from the interior edge of the nearest foundation a minimum of 12 inches. In addition, the trench should be located such that an imaginary line extending downward at a 45-degree angle from the foundation does not intersect the nearest edge of the trench. Gravel should extend a minimum of 3 inches beneath the bottom of the pipe. The under-slab drainage system should be sloped at a minimum 1/8 inch per foot to a suitable outlet, such as a sump and pump system. The under-slab drainage layer should consist of a minimum 6-inch thickness of free-draining gravel meeting the specifications of ASTM C33, Size No. 57 or 67 or equivalent. Cross-connecting drainage pipes should be provided beneath the slab at minimum 15-foot intervals and should discharge to the perimeter drainage system. Sizing of drainage pipe will be dependent upon groundwater flow into the dewatering system. Groundwater flow rates will fluctuate with permeability of the soils to be dewatered and the depth to which groundwater may rise in the future. Pump tests to determine groundwater flow rates are recommended in order to properly design the system. For preliminary design purposes, the drainage pipe, sump, and pump system should be sized for a projected flow of 0.5 x 10-3 cubic feet per second (cfs) per lineal foot of drainage pipe. Additional recommendations can be provided upon request and should be presented in final subsurface exploration reports for each residential lot. Preliminary Pavement Subgrades Fill materials required to develop the pavement subgrades should consist of approved, low-volume change materials, free from organic matter and debris. Imported structural fill materials similar to CDOT Class 5, 6 or 7 base course material could be used in these areas. We recommend those fill soils be placed as recommended in the Site Preparation section of this report. The essentially cohesive soils may show strength loss and instability when wetted. Stabilization of those subgrades could be necessary at the time of construction to develop a stable platform for subsequent paving. Stabilization could be predesigned into the subgrades to mitigate swell, and the stabilized subgrades would be considered a part of the pavement section. Consideration could be given to a fly ash treatment concept for swell mitigation and/or stabilization, should pumping conditions develop. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 10 If a subgrade stabilization concept is chosen/required, consideration could be given to incorporating Class C fly ash within the upper 12-inches of the site pavements prior to construction of the overlying pavement structure. Stabilization should consist of blending 13% by dry weight of Class C fly ash in the top 12 inches of the subgrades. The blended materials should be adjusted in moisture content to slightly dry of standard Proctor optimum moisture content and compacted to at least 95% of the material’s maximum dry density as determined in accordance with the standard Proctor procedure. Compaction of the subgrade should be completed within two hours after initial blending of the Class C fly ash. Pavement sections are based on assumed traffic volumes and subgrade strength characteristics. Based on the materials encountered, we believe an estimated R-value of 10 would be appropriate for design of the pavements supported on the subgrade soils. Suggested preliminary pavement sections for the light duty and heavy-duty on-site pavement improvement sections are provided below in Table III. A final pavement design thickness evaluation will be determined when a pavement design exploration is completed (after subgrades are developed to ± 6 inches of design and wet utilities installed). Hot mix asphalt (HMA) underlain by aggregate base course, or a non-reinforced concrete pavement may be feasible options for the proposed on-site paved sections. HMA pavements may show rutting and distress in areas of heavy truck traffic or in truck loading and turning areas. Concrete pavements should be considered in those areas. Table III –Recommended Minimum Pavement Sections Automobile Parking Heavy Duty Areas 18-kip EDLA 18-kip ESAL’s Reliability Resilient Modulus (R = 10) PSI Loss 7 51,100 75% 3562 psi 2.5 15 109,500 85% 3562 psi 2.2 Design Structure Number 2.47 2.96 (A) Composite Hot Bituminous Pavement Aggregate Base (Design Structural Number) 4" 7" (2.53) 5" 7" (2.97) (B) Composite with Fly Ash Treated Subgrade Hot Bituminous Pavement Aggregate Base Fly Ash Treated Subgrade (Design Structure Number) 3½" 6" 12" (2.70) 4" 7" 12" (3.03) (C) PCC (Non-reinforced) 5" 6" Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 11 Asphalt surfacing should consist of grading S-75 or SX-75 hot bituminous pavement with PG 64-22 or PG 58-28 binder in accordance with LCUASS. Aggregate base should be consistent with CDOT requirements for Class 5 or Class 6 aggregate base. As previously mentioned, a final subgrade investigation and pavement design should be performed in general accordance with LCUASS standards prior to placement of any pavement sections, to determine the required pavement section after design configurations, roadway utilities have been installed and roadway have been prepared to “rough” subgrade elevations have been completed. Underground Utility Systems All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded gravel compacted to 70 percent of Relative Density ASTM D4253 be used as bedding. Where utilities are excavated below groundwater, temporary dewatering will be required during excavation, pipe placement and backfilling operations for proper construction. Utility trenches should be excavated on safe and stable slopes in accordance with OSHA regulations as further discussed herein. Backfill should consist of on-site soils or approved imported materials. The pipe backfill should be compacted to a minimum of 95 percent of Standard Proctor Density ASTM D698. Water Soluble Sulfates (SO4) The water-soluble sulfate (SO4) content of the on-site overburden subsoils, taken during our subsurface exploration at random locations and intervals are provided below. Based on reported sulfate content test results, the Class/severity of sulfate exposure for concrete in contact with the on- site subsoils is provided in this report. Table IV - Water Soluble Sulfate Test Results Sample Location Description % of Soil by Weight B-8 S-2 4' Sandy Lean Clay (CL) 0.06 Based on the results as presented above, ACI 318, Section 4.2 indicates the site soils have a low risk of sulfate attack on Portland cement concrete, therefore, ACI Class S0 requirements should be followed for concrete placed in the overburden soils. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 12 Other Considerations Positive drainage should be developed away from the structure with a minimum slope of 1-inch per foot for the first 10-feet away from the improvements in landscape areas. Flatter slopes could be used in hardscapes areas although positive drainage should be maintained. Care should be taken in planning of landscaping adjacent to the building, parking, and drive areas to avoid features which would pond water adjacent to the pavements, foundations, or stem walls. 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. Excavations into the on-site soils may encounter a variety of conditions. Excavations into the on-site clay soils can be expected to stand on relatively steep temporary slopes during construction while excavations extending to the gravel/sand soils may experience caving/sloughing. 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 earthwork phases to help determine that the design requirements are fulfilled. This report has been prepared for the exclusive use for TDC-Development 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 Earth Engineering Consultants, LLC EEC Project No. 1232071 October 10, 2023 Page 13 recommendations contained in this report shall not be considered valid unless the changes are reviewed, and the conclusions of this report are modified or verified in writing by the geotechnical engineer. Earth Engineering Consultants, LLC DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample ST: Thin‐Walled Tube ‐ 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 falling 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 DCI: Dry Cave in BCR: Before Casing Removal AB : After Boring ACR: After Casting Removal Water levels indicated on the 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 #200 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: Hard Difficult to scratch with knife. Moderately Can be scratched easily with knife. Hard Cannot be scratched with fingernail. Soft Can be scratched with fingernail. Shale, Siltstone and Claystone: 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 Conglomerate: Well Capable of scratching a knife blade. Cemented Cemented Can be scratched with knife. Poorly Can be broken apart easily with fingers. Cemented Group Symbol Group Name Cu≥4 and 1<Cc≤3E GW Well-graded gravel F Cu<4 and/or 1>Cc>3E GP Poorly-graded gravel F Fines classify as ML or MH GM Silty gravel G,H Fines Classify as CL or CH GC Clayey Gravel F,G,H Cu≥6 and 1<Cc≤3E SW Well-graded sand I Cu<6 and/or 1>Cc>3E SP Poorly-graded sand I Fines classify as ML or MH SM Silty sand G,H,I Fines classify as CL or CH SC Clayey sand G,H,I inorganic PI>7 and plots on or above "A" Line CL Lean clay K,L,M PI<4 or plots below "A" Line ML Silt K,L,M organic Liquid Limit - oven dried Organic clay K,L,M,N Liquid Limit - not dried Organic silt K,L,M,O inorganic PI plots on or above "A" Line CH Fat clay K,L,M PI plots below "A" Line MH Elastic Silt K,L,M organic Liquid Limit - oven dried Organic clay K,L,M,P Liquid Limit - not dried Organic silt K,L,M,O Highly organic soils PT Peat (D30)2 D10 x D60 GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line. GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line. GP-GM poorly-graded gravel with silt PPI plots on or above "A" line. GP-GC poorly-graded gravel with clay QPI plots below "A" line. 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 Earth Engineering Consultants, LLC IIf soil contains >15% gravel, add "with gravel" to group name JIf Atterberg limits plots shaded area, soil is a CL- ML, Silty clay Unified Soil Classification System Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests Sands 50% or more coarse fraction passes No. 4 sieve Fine-Grained Soils 50% or more passes the No. 200 sieve <0.75 OL Gravels with Fines more than 12% fines Clean Sands Less than 5% fines Sands with Fines more than 12% fines Clean Gravels Less than 5% fines Gravels more than 50% of coarse fraction retained on No. 4 sieve Coarse - Grained Soils more than 50% retained on No. 200 sieve CGravels with 5 to 12% fines required dual symbols: Kif soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel", whichever is predominant. <0.75 OH Primarily organic matter, dark in color, and organic odor ABased on the material passing the 3-in. (75-mm) sieve ECu=D60/D10 Cc= HIf fines are organic, add "with organic fines" to group name LIf soil contains ≥ 30% plus No. 200 predominantly sand, add "sandy" to group name. MIf soil contains ≥30% plus No. 200 predominantly gravel, add "gravelly" to group name. DSands with 5 to 12% fines require dual symbols: BIf field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name.FIf soil contains ≥15% sand, add "with sand" to GIf fines classify as CL-ML, use dual symbol GC- CM, or SC-SM. Silts and Clays Liquid Limit less than 50 Silts and Clays Liquid Limit 50 or more 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 110 PL A S T I C I T Y I N D E X ( P I ) LIQUID LIMIT (LL) ML OR OL MH OR OH For Classification of fine-grained soils and fine-grained fraction of coarse-grained soils. Equation of "A"-line Horizontal at PI=4 to LL=25.5 then PI-0.73 (LL-20) Equation of "U"-line Vertical at LL=16 to PI-7, then PI=0.9 (LL-8) CL-ML TDC – MULTI-USE DEVELOPMENT ON MULBERRY FORT COLLINS, COLORADO EEC PROJECT NO. 1232071 SEPTEMBER 2023 B-1 B-2 B-3 B-4 1 2 Boring Location Diagram Mulberry Street Mixed-Use-Development Fort Collins, Colorado EEC Project #: 1232071 Date: October 2023 EARTH ENGINEERING CONSULTANTS, LLC Approximate Boring Locations 1 Legend Site PKotos PKotos taNen in approximate location, in direction oI arroZ DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF SPARSE VEGETATION _ _ 1 SANDY LEAN CLAY (CL)_ _ brown 2 medium stiff _ _ CS 3 4 5500 12.1 111.2 _ _ 4 _ _Water-Soluble Sulfate Content = 0.06% CS 5 5 1000 12.9 107.7 26 7 51.4 <500 PSF None _ _ 6 _ _ 7 _ _ 8 _ _ 9 _ _ CS 10 8 2500 20.9 100.9 _ _ 11 _ _ SILTY SAND WITH GRAVEL (SM)12 brown/red/white _ _ medium dense to loose 13 with intermittent clay seams _ _ 14 _ _ CS 15 24 4.6 120.9 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ *clay seams CS 20 6 11.0 113.7 18.7 _ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ CS 25 4 22.2 BOTTOM OF BORING DEPTH 25'_ _ Earth Engineering Consultants, LLC A-LIMITS SWELL SURFACE ELEV N/A FINISH DATE 9/14/2023 9/20/2023 8' SHEET 1 OF 1 WATER DEPTH START DATE 9/14/2023 WHILE DRILLING 10.5' MULBERRY ST MIXED USE DEVELOPMENT LOG OF BORING B-1PROJECT NO: 1232071 SEPTEMBER 2023 FORT COLLINS, COLORADO DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 SANDY LEAN CLAY (CL)_ _ brown 2 very stiff _ _ 3 _ _ 4 _ _ CS 5 16 9000+11.4 123.4 _ _ 6 _ _ 7 _ _ 8 _ _ WELL GRADED SAND WITH GRAVEL (SW)9 brown/red/white _ _ dense CS 10 34 7.9 127.6 4.6 with intermittent clay seams _ _ 11 _ _ 12 _ _ 13 _ _ 14 _ _ CS 15 39 11.6 130.1 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ CS 20 40 9.2 133.0 BOTTOM OF BORING DEPTH 20'_ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC MULBERRY ST MIXED USE DEVELOPMENT PROJECT NO: 1232071 LOG OF BORING B-2 SEPTEMBER 2023 FORT COLLINS, COLORADO SHEET 1 OF 1 WATER DEPTH START DATE 9/14/2023 WHILE DRILLING 10' SURFACE ELEV N/A FINISH DATE 9/14/2023 9/20/2023 8.7' A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 CLAYEY-SILTY SAND (SC-SM)_ _ brown 2 medium dense _ _ with calcareous deposits 3 _ _ 4 _ _ CS 5 16 4500 26.7 100.6 24 5 39.6 <500 PSF None _ _ 6 _ _ 7 _ _ SANDY LEAN CLAY (CL)8 brown _ _ medium stiff 9 _ _ CS 10 4 1500 25.4 96.5 31 8 56.0 <500 PSF None _ _ 11 _ _ SAND / GRAVEL (SP / GP)12 brown/red/white _ _ medium dense 13 _ _ 14 _ _ CS 15 22 14.7 103.6 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ CS 20 16 12.4 BOTTOM OF BORING DEPTH 20'_ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC MULBERRY ST MIXED USE DEVELOPMENT PROJECT NO: 1232071 LOG OF BORING B-3 SEPTEMBER 2023 FORT COLLINS, COLORADO SHEET 1 OF 1 WATER DEPTH START DATE 9/14/2023 WHILE DRILLING 12' SURFACE ELEV N/A FINISH DATE 9/14/2023 9/20/2023 11' A-LIMITS SWELL DATE: RIG TYPE: CME55 FOREMAN: DG AUGER TYPE: 4" CFA SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200 TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF VEGETATION AND TOPSOIL _ _ 1 SANDY LEAN CLAY (CL)_ _ brown 2 very stiff to soft _ _ CS 3 22 9000+10.8 112.2 <500 PSF None _ _ 4 _ _ CS 5 21 9000+11.6 122.0 _ _ 6 _ _ 7 _ _ 8 _ _ 9 _ _ CS 10 3 500 13.1 117.4 _ _ 11 _ _ 12 _ _ SAND / GRAVEL (SP / GP)13 brown/red/white _ _ dense to medium dense 14 _ _ CS 15 42 10.6 132.9 _ _ 16 _ _ 17 _ _ 18 _ _ 19 _ _ CS 20 26 9.9 132.2 BOTTOM OF BORING DEPTH 20'_ _ 21 _ _ 22 _ _ 23 _ _ 24 _ _ 25 _ _ Earth Engineering Consultants, LLC A-LIMITS SWELL SURFACE ELEV N/A FINISH DATE 9/14/2023 9/20/2023 10.5' SHEET 1 OF 1 WATER DEPTH START DATE 9/14/2023 WHILE DRILLING 12' MULBERRY ST MIXED USE DEVELOPMENT PROJECT NO: 1232071 LOG OF BORING B-4 SEPTEMBER 2023 FORT COLLINS, COLORADO Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description:Brown Sandy Lean Clay Sample Location:Boring 1, Sample 2, Depth 4' Liquid Limit: 26 Plasticity Index: 7 % Passing #200: 51.4% Beginning Moisture: 12.9%Dry Density: 106.3 pcf Ending Moisture: 17.4% Swell Pressure: <500 psf % Swell @ 500:None Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 September 2023 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o n Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description:Brown Sandy Lean Clay Sample Location:Boring 2, Sample 1, Depth 4' Liquid Limit: - -Plasticity Index: - -% Passing #200: - - Beginning Moisture: 11.4%Dry Density: 119.3 pcf Ending Moisture: 10.6% Swell Pressure: <500 psf % Swell @ 500:None Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 September 2023 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o n Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description:Brown Clayey-Silty Sand (SC-SM) Sample Location:Boring 3, Sample 1, Depth 4' Liquid Limit: 24 Plasticity Index: 5 % Passing #200: 39.6% Beginning Moisture: 26.7%Dry Density: 97.6 pcf Ending Moisture: 16.7% Swell Pressure: <500 psf % Swell @ 500:None Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 September 2023 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o n Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description:Brown Sandy Lean Clay Sample Location:Boring 3, Sample 2, Depth 9' Liquid Limit: 31 Plasticity Index: 8 % Passing #200: 56.0% Beginning Moisture: 25.4%Dry Density: 94.1 pcf Ending Moisture: 27.9% Swell Pressure: <500 psf % Swell @ 500:None Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 September 2023 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o n Water Added Project: Location: Project #: Date: SWELL / CONSOLIDATION TEST RESULTS Material Description:Brown Sandy Lean Clay Sample Location:Boring 4, Sample 1, Depth 2' Liquid Limit: - -Plasticity Index: - -% Passing #200: - - Beginning Moisture: 10.8%Dry Density: 102.6 pcf Ending Moisture: 16.4% Swell Pressure: <500 psf % Swell @ 500:None Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 September 2023 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0 6.0 8.0 10.0 0.01 0.1 1 10 Pe r c e n t M o v e m e n t Load (TSF) Sw e l l Co n s o l i d a t i o n Water Added 2 1/2"(63 mm) 2"(50 mm) 1 1/2"(37.5 mm) 1"(25 mm) 3/4"(19 mm) 1/2"(12.5 mm) 3/8"(9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project:Mulberry Street Mixed-Use-Development Location:Fort Collins, Colorado Project No:1232071 Sample ID:B1 S4 19 Sample Desc.:Silty Sand with Gravel (SM) Date:October 2023 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 100 98 85 80 70 59 26 18.7 56 50 43 38 34 0.23 --- Fine ------ D30 D10 Cu CC October 2023 25.00 2.66 1.19 Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 B1 S4 19 Silty Sand with Gravel (SM) D100 D60 D50 EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size 2 1/2"(63 mm) 2"(50 mm) 1 1/2"(37.5 mm) 1"(25 mm) 3/4"(19 mm) 1/2"(12.5 mm) 3/8"(9.5 mm) No. 4 (4.75 mm) No. 8 (2.36 mm) No. 10 (2 mm) No. 16 (1.18 mm) No. 30 (0.6 mm) No. 40 (0.425 mm) No. 50 (0.3 mm) No. 100 (0.15 mm) No. 200 (0.075 mm) Project:Mulberry Street Mixed-Use-Development Location:Fort Collins, Colorado Project No:1232071 Sample ID:B2 S2 9 Sample Desc.:well Graded Sand with Gravel (SW) Date:October 2023 EARTH ENGINEERING CONSULTANTS, LLC SUMMARY OF LABORATORY TEST RESULTS Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136) 100 Sieve Size Percent Passing 100 100 100 100 100 97 81 56 8 4.6 52 40 27 21 15 0.73 0.19 Fine 14.02 1.03 D30 D10 Cu CC October 2023 12.50 2.70 1.87 Mulberry Street Mixed-Use-Development Fort Collins, Colorado 1232071 B2 S2 9 well Graded Sand with Gravel (SW) D100 D60 D50 EARTH ENGINEERING CONSULTANTS, LLC Summary of Washed Sieve Analysis Tests (ASTM C117 & C136) Date: Project: Location: Project No: Sample ID: Sample Desc.: Cobble Silt or ClayGravel Coarse Fine Sand Coarse Medium 6" 5" 4" 3" 2.5" 2" 1.5" 1" 3/4" 1/2" 3/8" No. 4 No. 8 No. 10 No. 16 No. 30 No. 40 No. 50 No. 100 No. 200 0 10 20 30 40 50 60 70 80 90 100 0.010.11101001000 Fi n e r b y W e i g h t ( % ) Grain Size (mm) Standard Sieve Size