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Home My WebLink AboutFREIGHT DEPOT PUD - PRELIMINARY - 29-95 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTEmpires Laboratories, Inc. A Division of The Terracon Companies, Inc. P.O. Box 503 • 301 No. Howes Fort Collins, Colorado 80522 (303) 484-0359 FAX No. (303) 484-0454 Chester C. Smith, P.E. Neil R. Sherrod, C.P.G. January 12, 1995 City of Fort Collins Facilities P. 0. Box 580 Fort Collins, Colorado 80522 Attn: Mr. Jack Gianola Re: Geotechnical Engineering Report, Proposed City of Fort Collins Storm Drainage Office Building, Fort Collins, Colorado ELI Project No. 20945281 Empire Laboratories, Inc. (ELI) has completed a geotechnical engineering exploration for the proposed project to be located between Maple Street and LaPorte Avenue east of North Mason Street in downtown Fort Collins, Colorado. This study was performed in general accordance with our proposal number D2094430 dated January 3, 1995. The results of our engineering study, including the boring location diagram, laboratory test results, test boring records, and the geotechnical recommendations needed to aid in the design and construction of foundations and other earth connected phases of this project are attached. The subsurface soils consisted of sandy lean clay underlain by well -graded gravel with silt, sand, cobbles and boulders. The subsoils are underlain by sandstone bedrock. The information obtained by the results of field exploration and laboratory testing completed for this study indicates the clays and gravels at the site exhibit moderate to high bearing Jcharacteristics and non to low swell potential. The bedrock exhibits very high bearing characteristics. Based on the geotechnical engineering analysis, subsurface exploration and laboratory test results, we recommend the proposed building be supported on a spread footing foundation system. Slab -on -grade may be utilized for the interior floor system provided that care is taken in the placement and compaction of the subgrade soil. Other design and construction details, based upon geotechnical conditions, are presented t in the report. Offices of The Terracon Companies, Inc. Geotechnical, Environmental and Materials Engineers Arizona: Tucson ■ Colorado: Colorado Springs, Denver, Ft. Collins, Greeley. Longmont ■ Idaho: Boise ■ Illinois: Bloomington, Chicago, Rock Island ■ Iowa: Cedar Falls, Cedar Rapids, Davenport, Des Moines, Storm Lake ■ Kansas: Lenexa, Topeka, Wichita ■ Minnesota: St. Paul ■ Missouri: Kansas City ■ Nebraska: Lincoln, Omaha ■ Nevada: Las Vegas ■ Oklahoma: Oklahoma City, Tulsa ■ Texas: Dallas, Fort Worth ■ Utah: Sall Lake City ■ Wyoming: Cheyenne QUALITY ENGINEERING SINCE 1965 J Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 3. Materials should be compacted to the following: Minimum Percent Material (ASTM D698) Subgrade soils beneath fill areas ..................... 95 On -site soils: Beneath foundations .......................... 98 Beneath slabs ............................. 95 Beneathpavements ......................... 95 i In utility trenches ........................... 95 Imported fill: Beneath foundations 98 Beneath slabs ............................. 95 Beneath pavements ......................... 95 In utility trenches ........................... 95 —y Aggregate base (beneath slabs) ...................... 95 Miscellaneous backfill ............................. 90 4. If a well defined maximum density curve cannot be generated by impact compaction in the laboratory for any fill type, engineered fill should be compacted to a minimum of 80 percent relative density by determined by ASTM D4253 D4254. 5. On -site soils should be compacted within a moisture content range of 2 percent below, to 2 percent above optimum. Imported soils should be compacted within a moisture range of 2 percent below to 2 percent above optimum. • Compliance: Recommendations for slabs -on -grade, foundations and pavement elements supported on compacted fills or prepared subgrade depend upon compliance with "Earthwork" recommendations. To assess compliance, observation and testing should be performed under the direction of the geotechnical engineer. • Excavation and Trench Construction: Excavations into the on -site soils will —) encounter a variety of conditions. Excavations into the clays and bedrock can be 15 UNIFIED SOIL CLASSIFICATION SYSTEM Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests" - Group Symbol Group Name 6 Coarse -Grained Gravels more than Clean Gravels Less Cu > 4 and 1 < Cc <3E GW Well -graded ravel' 9 9 Soils more than 50% of coarse than 5% finesc 50% retained on fraction retained on Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravel` No. 200 sieve No. 4 sieve Gravels with Fines 12% finesc Fines classifyas ML or MH GM Silty gravel,G,H more than Fines classify as CL or CH. GC Clayey gravelr.G." Sands 50% or more Clean Sands Less Cu > 6 and 1 < Cc < 3E SW Well -graded sand' of coarse fraction than 5% finesE Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sand' passes No. 4 sieve Sands with Fines Fines classify as ML or MH SM Silty sands•"•' more than 12% fines° Fines Classify as CL or CH SC Clayey sands•"•' Fine -Grained Soils Sifts and Clays inorganic PI > 7 and plots on or above "A line' CL Lean clay'`" 50% or more Liquid limit less PI < 4 or plots below "A' line' ML Silt't"" passes the than 50 No. 200 sieve organic Liquid limit - oven dried Organic claylIL"•" OL Liquid limit - not dried Organic silt'•"•O Silts and Clays inorganic PI plots on or above "A" line CH Fat clay"••." Liquid limit 50 PI lots below "A" line MH Elastic Silt K�" or more organic Liquid limit - oven dried Organic clay`•u"•P OH Liquid limit - not dried Organic sih"•L•"•o iighly organic soils Primaril kBased on the material passing the 3-in. (75-mm) sieve 'If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. 'Gravels with 5 to 12% fines require dual symbols: GW-GM well -graded gravel with silt GW-GC well -graded gravel with clay GP -GM poorly graded gravel with silt GP -GC poorly graded gravel with clay 'Sands with 5 to 12% fines require dual symbols: SW-SM well -graded sand with silt SW -SC well -graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay 60 v organic matter, dark in color, and organic odor (D36) 5 aCu=$o1Di0 Cc T. X Dca 'If soil contains > 15% sand, add "with sand" to group name. °If fines classify as CL-ML, use dual symbol GC -GM, or SC-SM. "If fines are organic, add "with organic fines" to group name. 'If soil contains > 15% gravel, add "with gravel" to group name. 'If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. PT Peat "If soil contains 15 to 29% plus No. 200, add .with sand" or "with gravel", whichever is predominant. LIf soil contains > 30% plus No. 200 predominantly sand, add "sandy" to group name. "If soil contains > 30% plus No. 200, predominantly gravel, add "gravelly" to group name. "PI > 4 and plots on or above "A" line. °PI < 4 or plots below "A" line. PPI plots on or above "A" line. oPl plots below "A" line. , For doulka"en el Mo—prvNod .oN / PIl.-g.1nod f,o~ at . 1, " zomP R to 25.5 "' (4 20) O P Fqud'v� el V - E. ' OR- / V / O MH all OH ML OR OL 0 0 10 16 zo w a w w 70 so tw ioo 11c LIQUM LIMIT (LL) Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. Geotechnical Engineering Exploration �) City of Fort Collins Facilities ELI Project No. 20945281 I I iU construction. To reduce any potential slab movements, the subgrade soils should be prepared as outlined in the "Earthwork" section of this report. For structural design of concrete slabs -on -grade, a modulus of subgrade reaction to 125 pounds per cubic inch (pci) may be used for floors supported on existing or engineered fill consisting of on -site soils. Additional floor slab design and construction recommendations are as follows: • Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines to allow independent movement. • Contraction joints should be provided in slabs to control the location and extent of cracking. Maximum joint spacing of 15 to 20 feet in each direction is recommended. • Interior trench backfill paced beneath slabs should be compacted in accordance with recommended specifications outlined below. • In areas.subjected to normal loading, a minimum 4-inch layer of clean -graded gravel should be placed beneath interior slabs. • If moisture sensitive floor coverings are used on interior slabs, consideration should be given to the use of barriers to minimize potential vapor rise through the slab. • 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 Design and Construction: The required total thickness for the pavement structure is dependent primarily upon the foundation soil or subgrade and upon traffic conditions. Based on the soil conditions encountered at the site, the type and volume of traffic and using a group index of 3 as the criterion for pavement design, the following minimum pavement thicknesses are recommended: TABLE D2 RECOMMENDED PREVENTATIVE MAINTENANCE POLICY FOR JOINTED CONCRETE PAVEMENTS Distress Distress Recommended Distress Distress Recommended Type Severity Maintenance Type Severity Maintenance Low None No Polished Severity Groove Surface Medium Full -Depth Blow-up Concrete Patch/ Aggregate Levels or Overlay High Slab Replacement Defined Low Seal Cracks No Comer Break Popouts Severity Levels None Medium Full Depth High Concrete Patch Defined Low Seal Cracks No Underseal, Divided Severity . Seal cracks/joints Slab Medium Slab Pumping Levels and Replacement Defined Restore High Load Transfer Low None Low Seal Cracks Medium Full -Depth Patch Medium Full -Depth Durability Punchout Cracking Concrete High Slab Replacement High Patch Low None Low No Faulting Railroad Crossing Policy' for this Medium Medium Grind High High Project Low None Scaling Low None Medium Medium Slab Replacement, Joint Map Cracking Seal Reseal Crazing Full -depth Patch, High Joints High or Overlay Low Regrade and No Lane/Shoulder Medium Fill Shoulders Shrinkage Severity None Drop-off to Match Cracks Levels High Lane Height Defined Linear Cracking Low Clean & Low None Longitudinal, Seal all Cracks Spelling Medium Transverse and Medium (Comer) Partial -Depth High Full -Depth Patch High Diagonal Cracks Concrete Patch Low None Low None Large Patching - Spoiling and Medium Seal Cracks or (Joint) Medium Partial -Depth Patch High High Reconstruct Joint Utility Cuts Replace Patch Low None Medium Replace Small Patching Path Empire Laboratories, Inc. I rHighl I A Division of The Terracon Companies, Inc. Distress Type Alligator Cracking Bleeding Block Cracking Bumps & Sags Corrugation Depression Edge Cracking Joint Reflection Lane/Shoulder Drop -Off Longitudinal & Transverse Cracking TABLE D1 _ RECOMMENDED PREVENTATIVE MAINTENANCE POLICY FOR ASPHALT CONCRETE PAVEMENTS Distress Severity Recommended Maintenance Distress Type Distress Severity Low None Patching & Utirty Cut Patching Low Medium Full -Depth Asphalt. Concrete Patch Medium High High Low None Polished Aggregate Low, Medium Surface Sanding Medium High Shallow AC Patch High Low None Potholes Low Medium Clean & Seal All Cracks Medium High High Low None Railroad Crossing Low . Medium Shallow AC Patch Medium High Full -Depth Patch High Low None Rutting Low . Medium Full -Depth Asphalt Concrete Patch Medium High High Low None Shoving Low Medium Shallow AC Patch Medium . High Full -Depth Patch High Low None Slippage Cracking Low Medium Seal Cracks Medium High Full -Depth Patch High Low Clean & Seal All Cracks well Low Medium Medium High Shallow AC Patch High Low None Low Medium Regrade Shoulder High Low None Medium Clean & Seal All Cracks High Weathering Medium & Ravelling High Recommended Maintenance None Full -Depth Asphalt Concrete Patch Fog Seal Shallow AC Patch Full -Depth Asphalt Concrete Patch No Policy for This Project None Shallow AC'Patch Full -Depth Patch None Mill & Shallow AC Patch None Shallow Asphalt Concrete Patch None Shallow AC Patch Full -Depth Patch Fog Seal Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. 1 D Expansive Potential Finished Grade s Footing Foundation Frost Depth I ,r REPORT TERMINOLOGY (Based on ASTM D653) The potential of a soil to expand (increase in volume) due to absorption of moisture. The final grade created as a part of the project. A portion of the foundation of a structure that transmits loads directly to the soil. The lower part of a structure that transmits the loads to the soil or bedrock. The depth of which the ground becomes frozen during the winter season. Grade Beam A foundation element or wall, typically constructed of reinforced concrete, used to span between other foundation elements such as drilled piers. Groundwater. Subsurface water found in the zone of saturation of soils, or within fractures in bedrock. Heave Upward movement. Lithologic The characteristics which describe the composition and texture of. soil and rock by observation. Native Grade The naturally occuring ground surface. Native Soil Naturally occurring on -site soil, sometimes referred to as natural soil. optimum Moisture The water content at which a soil can be compacted to a maximum dry unit Content weight by a given compactive effort. Perched Water Groundwater, usually of limited area maintained above a normal water - elevation by the presence of an intervening relatively impervious continuing stratum. Scarify To mechanically loosen soil or break down existing soil structure. Settlement Downward movement. Skin Friction (Side The frictional resistance developed between soil and an element of structure Shear) such as a drilled pier or shaft. Soil (earth) Sediments or other unconsolidated accumulations of solid particles produced by the physical and chemical disintegration of rocks, and which may or may not contain organic matter. Strain The change in length per unit of length in a given direction. Stress The force per unit area acting within a soil mass. Strip To remove from present location. Subbase A layer of specified material in a pavement system between the subgrade and base course. Subgrade The soil prepared and compacted to support a structure, slab or pavement system. r L Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. i I I] I REPORT TERMINOLOGY (Based on ASTM D653) Allowable Soil The recommended maximum contact stress developed at the interface of the Bearing Capacity foundation element and the supporting material. Alluvium Soil, the constituents of which have been transported in suspension by flowing water and subsequently deposited by sedimentation. Aggregate Base A layer of specified material placed on a subgrade or subbase usually beneath Course slabs or pavements. Backfill A specified material placed and compacted in a confined area. Bedrock A natural aggregate of mineral grains connected by strong and permanent cohesive forces. Usually requires drilling, wedging, blasting or other methods of extraordinary force for excavation. Bench A horizontal surface in a sloped deposit. Caisson (Drilled pier A concrete foundation element cast in a circular excavation which may have an or Shaft) enlarged base. Sometimes referred.to as a cast -in -place pier or drilled shaft. . Coefficient of A constant proportionality'factor relating normal stress and the corresponding Friction shear stress at which sliding starts between the two surfaces. Coluuvium Soil, the constituents of which have been deposited .chiefly by gravity such as at the foot of a slope or cliff. Compaction The densification of a soil by means of mechanical manipulation. Concrete Slab -on- A concrete surface layer cast directly upon a base, subbase or subgrade, and Grade typically used as a floor system. Differential Unequal settlement or heave between, or within foundation elements of a Movement structure. Earth Pressure The pressure or force exerted by soil on any boundary such as a foundation wall. ESAL Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000 pound axle loads). Engineered Fill Specified material placed and compacted to specified density and/or moisture conditions under observations of a representative of a geotechnical engineer. Equivalent Fluid A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral support presumed to be equivalent to that produced by the actual soil. This simplified approach is valid only when deformation conditions are such that the pressure increases linearly with depth and the wall friction is neglected. Existing Fill (or Materials deposited through the action of man prior to exploration of the site. man-made fill) Existing Grade The ground surface at the_ time of field exploration. K Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. LABORATORY TESTS SIGNIFICANCE AND PURPOSE TEST SIGNIFICANCE PURPOSE Ca//fornia Used to evaluate the potential strength of subgrade soil, subbase, Pavement Bearing and base course material, including recycled materials for use in Thickness Ratio road and airfield pavements. Design Used to develop an estimate of both the rate and amount of both Foundation Consolidation differential and total settlement of a structure. Design Used to determine the consolidated drained shear strength of soil Bearing Capacity, Direct or rock. Foundation Design & Shear Slope Stability Dry Used to determine the in -place density of natural, inorganic, fine- Index Property Density grained soils. Soil Behavior Used to measure the expansive potential of fine-grained soil and to Foundation & Slab Expansion provide a basis for swell potential classification. Design Used for the quantitative determination of the distribution of Soil Gradation particle. sizes in soil. Classification Liquid & Used as an integral part of engineering classification systems to Soil Plastic Limit, characterize the fine-grained fraction of soils, and to specify the Classification Plasticity Index fine-grained fraction of construction materials. Oxidation- Used to determine the tendency of the soil to donate or accept Corrosion Reduction electrons through a change of the oxidation state within the soil. Potential Potential Used to determine the capacity of soil or rock to conduct a liquid Groundwater Permeability or gas. Flow Analysis Used to determine the degree of acidity or alkalinity of a soil. Corrosion p H Potential Used to indicate the relative ability of a soil medium to carry Corrosion Resistivity electrical currents. Potential Used to evaluate the potential strength of subgrade soil, subbase, Pavement R-Value and base course material, including recycled materials for use in Thickness road and airfield pavements. Design Soluble Used to determine the quantitative amount of soluble sulfates Corrosion Sulphate within a soil mass. Potential Used to determine the quantitative amounts of sulfides within a Corrosion Su/fide Content soil mass. Potential To obtain the approximate compressive strength of soils that Bearing Capacity Unconfined possess sufficient cohesion to permit testing in the unconfined Analysis for Compression state. Foundations water Used to determine the quantitative amount of water in a soil mass. Index Property Content Soil Behavior Empire Laboratories, Inc. Inc i� 1 ROCK CLASSIFICATION (Based on ASTM C-294) Sedimentary Rocks Sedimentary rocks are stratified materials laid down by water or wind. The sediments may be { composed of particles of pre-existing rocks derived by mechanical weathering, evaporation or by chemical or organic origin. The sediments are usually indurated by cementation or compaction. iChert Very fine-grained siliceous rock composed of micro -crystalline or crypto- crystalline quartz, chalcedony or opal. Chert is various colored, porous to dense, hard and has a conchoidal to splintery fracture. ' Claystone Fine-grained rock composed of or derived by erosion of silts and clays or any rock containing clay. Soft massive; gray, black, brown, reddish or green and ? may contain carbonate minerals. 1 Conglomerate Rock consisting of a considerable amount of rounded gravel, sand and cobbles with or without interstitial or cementing material. The cementing or interstitial material may be quartz, opal, calcite, dolomite, clay, iron oxides or other materials. Dolomite A fine-grained carbonate rock consisting of the mineral dolomite [CaMg (CO3)21. May contain noncarbonate impurities such as quartz, chert, clay minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). Limestone A fine-grained carbonate rock consisting of the mineral calcite (CaCo3). May contain noncarbonate impurities such as quartz, chart, clay minerals, organic j matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). I Sandstone Rock consisting of particles of sand with or without interstitial and cementing materials. The cementing or interstitial material may be quartz, opal, calcite, dolomite, clay, iron oxides or other material. Shale Fine-grained rock composed of, or derived by erosion of silts and clays or any rock containing clay. Shale is hard, platy, or fissile may be gray, black, • reddish or green and may contain some carbonate minerals (calcareous shale). t Siltstone Fine grained rock composed of, or derived by erosion of silts or rock containing silt. Siltstones consist predominantly of silt sized particles (0.0625 to 0.002 mm in diameter) and are intermediate rocks between claystones and sandstones, may be gray, black, brown, reddish or green and may contain i carbonate minerals. i i Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: SS :-Split Spoon - 13/a" 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 DC : Dutch Cone WB : Wash Bore Penetration Test: 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 DO : 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 groundwater: In low permeability soils, the accurate determination of groundwater 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-2487 and D-2488. Coarse Grained Soils have more 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, au, 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 Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. � SUNMARY OF (r�"ST RESULTS PROJECT NO. 20945281 ) Boring No. Depth Ft. Moisture % Dry Density Compressive Strength Swell Pressure Soluble Sulfates pH Liquid Limit Plasticity Index Group Index Classification AASHTO Resistivity (OHM -CM) Penetration Blow/In. 4-5 4/12 4-5 32/12 5-6 58/12 SVI�'11ViL1.<�__.. -- Y OF `r1 ST RESULTS PROJECT NO. 20945281 Boring Depth Moisture Dry Compressive Swell Soluble pH Liquid Plasticity Group Classification Resistivity Penetration No. Ft. % Density Strength Pressure Sulfates Limit Index Index AASHTO (OHM -CM) Blow/In. (PCF) (PSF) (PSF) % % % USCS 31/12 6 3-4 9 117 37/12 4-5 4 50l6 8-8.5 2 50/8 14-14.7 23 2 1-2 13 17/12 3-4 18 104 2520 27 8 3 A4(3); CL 4-5 14 49/12 8-8.8 3 50/9 14-14.8 22 50/9 3 .5-1.5 16 12/12 1.5-2.5 8/12 34 16 117 1820 4-5 7 10/12 5-6 52/1" 9.5-10.5 4 28/12 14-14.2 50/11h 4 1-2 8 8/12 3-4 15 103 1060 4-4.1 1 1 1 1 1 50/1 .4 2 .4 H 4 rzjc CONSOLIDATION TEST. PRO. 205452:31 BORING NO. 3 DEPTH: 3.0 DRY DENSIT11":117.5 PCF MOISTURE- 14.5 % 06%11 330 0.1 4.0 2.0 0.0 -2.0 4.0 -8 .0 El . '25 H3. 5 1.0 5 10 .APPLIED PRESSURE - TSF 0.25 0.5 1.0 ; APPLIED PRESSURE - TSF 5 10 EMPIRE LF9BORHTOPIES INC, 1 .a SWELL - CONSOL IDAT ION TEST PRO. 20945281 _nJ BORING NID.: I 9�+ DEPTH: 3.0 DRY DENSITY.-1E0.7 PCF MOISTURE: 9.9 % 70 51j 50 40 30 20 0.5 1.0 5 10 APPLIED PRESSURE — TSF 4.0 J J W 2.0 U7 X 0.0 WRTER. ADDED -8 .0 0.1 0.25 0.5 a1.0 APPLIED PRESSURE — TSF EMPIRE LHLORHTORI ES INC. 5 10 LOG OF BORING No. 6 Page 1 of 1 CLIENT - -- City of Fort Collins Facilities SITE C & S Depot PROJECT Fort Collins, Colorado Storm Drainage Office Building SAMPLES TESTS \ r J co J W z H� DESCRIPTION > cn o: W w z\ x w tL r, H x w � I In o zz d H UWtL a U z d 0 F-o i-LL w In > > w D- _j o o U z F- cn CDApprox. Surface Elev.: 96.5 ft. a z m m CO E Co m cn a FILL -Silty sand with eravel CL 1 12" 29 6 Black, moist, medium dense I . ISSI 2 0 94.5 2 SS 12" 16 WELL GRADED GRAVEL WITH crr T SAND_ COBBLES, 6.5 AND BOULDERS Brown, moist to wet Dense to extremely dense (Cobbles and boulders 6.5 ft.) 11.5 WEATHERED SANDSTONE 12.5 Tan, moist, moderately cemented SANDSTONE Tan, moist, well cemented 14.4 i 90.0 GM 3 SS 12" 32 1 1 5 4 1 SS 1 12"1 58 10 NR 1 50/2 82.1 1 1 1 61 SS 1 5"1 50/5 1 17 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE .TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated of Terracon BORING STARTED 14-95 g None WD T 13.0, A.B. BORING COMPLETED 1-4-95 rWL RIG CME-55 FOREMAN DML Water checkedDivision 2 days A.B. APPROVED N12S JOB" LOG OF BORING No. 5 Page 1 of 1 CLIENT ARCHITECT/ENGINEER City of Fort Collins Facilities SITE C & S Depot PROJECT Fort Collins, Colorado Storm Drainage Office Building SAMPLES TESTS I— o CD o a J U- E Y W (~A ' Z 2 H DESCRIPTION } fA W W z D z W HF- LL LD 2 W CO z W° U (JI O a. Y U W F-O 0-J H O }LL WL) U�0- LL ZF-(n Approx. Surface Elev.: 95.0 ft. o Z i W (n m E o o- :3 (n o- 0.3 2" ASPHALT 94.7 0,5 4" BASE COURSE 94.5 SM 1 SS 12" 16 8 1.5 FTi T .-Silty sand with gravel 93.5 Black, moist, medium dense GW 2 ST 12" 8 M e WELL GRADED GRAVEL WITH 3 SS 12" 4 SILT SAND COBBLES, AND BOULDERS 5 Brown, moist to wet Loose to very dense I i� 4 SS NR 68 �' 10 11.0 84.0 WEATHEREDSANDSTONE _ Tan, moist, moderately cemented - 12.5 82.5 SANDSTONE Tan, moist, well cemented 14.3 80.7 =. 5 1 SS 3.5" 0/3.5 11 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Terracon BORING STARTED 14-95 WL Q None W.D. 11.7, A.B. BORING COMPLETED 1-4-95 WL 1,WL RIG ME-55 FOREMAN DML Water checked 2 days A.B. APPROVED NRS JOB H 2O945281 LOG OF BORING No. 4 Page 1 of 1 CLIENT ARCHITECT/ENGINEER City of Fort Collins Facilities STTE C & S Depot PROJECT Fort Collins, Colorado Storm Drainage Office Building SAMPLES- TESTS I \ >- O (D J O no W W NLl- Z x H DESCRIPTION } Nw z o z H � I O o zz Ow a U (n z .:3 aU } W �o (L _j O rW Q: U UWL Z F (n 0 Approx. Surface Elev.: 97.5 ft. O x z 0: to CO s OIL m N IL 0.3 3" ASPHALT 97.2 0.5 3" BASE COURSE 97.0 CL I 1 SS 12" 8 8 1.5 FILL -Silly sand with gravel 96.0 Black, moist, loose CL CANDY LEAN CLAY Y WITH GRAVEL 2 ' ST 12" 15 103 1060 Brown, moist, medium to stiff 4.0 93.5 3 SS NR 50/1 S e: WELL GRADED GRAVEL WITH SILT, SAND. COBBLES, AND BOULDERS Brown, dry to wet GW 4 SS 12" 35 3 Dense to extremely dense M 0 10 es 12.5 85.0 1-14.0 WE THFREDSANDSTONE Tan, moist, moderately cemented 83.5 14.5 SANDSTONE 83.0 Tan, moist, well cemented 1 5 SS 6" 50/6 21 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS BORING STARTED 14-95 Empire Laboratories Incorporated Division of Terracon Q None W.D.i 12.0' A.B. BORING COMPLETED 1-4-95 r�- , L RIG CME-55 FOREMAN DML WL Water checked 2 days A.B. APPROVED NRS JOB # 2094528, LOG OF BORING No. 3 Page 1 of 1 CLIENT ARCHTTECT/ENGINEER City of Fort Collins Facilities SITE C & S Depot PROJECT Fort Collins, Colorado Storm Drainage Office Building SAMPLES TESTS o o o J LLLL E Y WH. W (n z2 c.I DESCRIPTION } m o: W W z� � z W HF- IL o H = i=- W m W O 3 f~A o W IL O_ W U o E a r U W � o O--j H o >- IL 0:u c) ix IL ZF-U) LLD Approx. Surface Elev.: 97.5 ft. o z o m E o O o rn o FILL -Silly sand with gravel SM I SS 12" 12 16 1.0 Black/brown, moist, medium dense 96.5 CL 2 SS 12" 8 SANDY LEAN CLAY WITH QRAVEL Brown, moist, medium to stiff 3 ST 12" 16 117 1820 4 SS 12" 10 7 5.0 92.5 5 GW 5 SS 12" 52 M WELL GRADED GRAVEL WITH SILT. SAND COBBLES AND BOULDERS Brown, dry K" Dense to extremely dense 6 SS 12" 78 4 (Cobbles and boulders 7.5 ft.) 10 11.5 86.0 WEATHERED SANDSTONE— i_ 12.5 Tan, moist, moderately cemented 85.0 SANDSTONE Tan, moist, well cemented _ — -• 14.1 83.4 7 SS NR 0/1.5 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES ' BETWEEN SOIL AND ROCK TYPES: IN -SITU; THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Terracon BORING STARTED 1-4-95 WL Y None WD• T 12.0' A.B. BORING COMPLETED 1-4-95 WL RIG CME-$5 FOREMAN DML WL Water checked 2 days A.B. APPROVED NRS JOB N 20945281 LOG OF BORING No. 2 Page 1 of 1 CLIENT ARCHITECT/ENGINEER City of Fort Collins Facilities SITE C & S Depot PROJECT Fort Collins, Colorado Storm Drainage Office Building SAMPLES TESTS F- � F_ o co o 0 LL � z H� w d H DESCRIPTION } cn W � w Z\ � w tL 0 CO N\ = 2 L•- (A W 00 W > O f Cn 3 F-- N O ZZ O W fYFJ W H(L a a- U E 0- U HO H > UfY LL F-L\ 0Approx. Surface Elev.: 97.5 ft. W o (A m O Z Y W W dJ Nm O E �U oa ZI—(A (n0- FH_I ¢_i_i FILL -Silly sand with gravel SM 1 SS 12" 17 13 Black/brown, moist, medium dense 2.0 95.5 27/19/8 CANDY LEAN CLAY WITH GRAVEL CL 2 ST 12" 18 104 2520 Brown, moist, stiff 93.5 4.0 GW 3 SS 12" 49 14 M I p WELL r.R ADED GRAVEL WITH SILT, SAND- _COBBLES. AND BOULDERS Brown, moist to wet Dense to extremely dense 4 SS 9" 50/9 3 (Cobbles below 5.5 ft.) 10 I to Q — L� 14.0 83.5 14.5 WE THERED SANDSTONE 83.0 5 SS 9" 50/9 22 Tan, moist, moderately cemented SANDSTONE Tan, moist, cemented BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION. MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Terracon BORING STARTED 14-95 WL Q 12 8' W.D. i BORING COMPLETED 14-95 wI 10.0' D.C.I. RIG CME-55 FOREMAN DML WI Water checked 2 days A.B. APPROVED NRS JOB N 20945281 3 �J LOG OF BORING No. 1 Page 1 of 1 CLIENT ARCHITECT/ENGINEER City of Fort Collins Facilities SITE C & S Depot PROJECT Fort Collins, Colorado Storm Drainage Office Building SAMPLES TESTS X >- uu_ E } v W (n z x H DESCRIPTION } Cl)W W w Z\ W =3 Z w H H U_ co za m m w o � M (n a zz ow O_ w U W Z: o d r U w 1_o a-_j H o YlL WU UXIL ZE-cn CD Approx. Surface Elev.: 97.5 ft. o o Z F- o m E o 0 o cn a . FILL-Sillysand with ravel SM 1 SS 12" 31 6 Black/brown, moist, dense 1 2.5 95.0 SANDY LEAN CLAY CL 2 ST 12" 9 117 Brown, moist, stiff 4.0 93.5 GW 3 SS 12" 37 4 M 5 Q WELL GRADED GRAVEL WITH SILT SAND. COBBLES. ' AND BOULDERS .4 SS 6" 50/6 2 # Brown, moist to wet Dense to extremely dense e. (Cobbles and boulders below 6 ft.) 10 SZ 13.0 84.5 WE THFREDSANDSTONE Tan, moist, moderately cemented 5 SS 8" 50/8 23 14.5 83.0 �Tan,ll cemented BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES ' BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Terracon BORING STARTED 14-95 W- g 11.7' W.D. _ BORING COMPLETED 1 4-95 wL 10.0' D.C•I• RIG CME_55 FOREMAN DML WL Water checked 2 days A.B. APPROVED AIRS JOB k 20945281 MAPLE 5ffEf 1.6.M. @ Krc. 60NNEf 601.E OF EX151116 FIRE HyVMf ON W. cawt LOADING OE MAPLE & MA50N %M f POCK ELEVATION - 100.0 No. 5 I No.6 I z O I No.4 �z O O � No.2 O _ \Z o fl oa I � No.1 La POI;Tf, AVENUE FIGURE 1: SITE PLAN MAPLE STREET & NORTH MASON STREET FORT COLLINS, COLORADO ELI. PROJECT No. 20945281 CITY OF Fort COLLIN5 OFFICES VACANT' LOT I� 3i 0 EX1511NG ' I %ILnING N SCALE 1" = 60' Empire Laboratories, Inc. A Division of The Terracon Companies. Inc. O }. Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 GENERAL COMMENTS It is recommended that the Geotechnical Engineer be retained to provide a general review of final design plans and specifications in order to' confirm that grading and foundation recommendations have been interpreted and implemented. In the event that any changes of the proposed project are planned, the conclusions and recommendations contained in this report should be reviewed and the report modified or supplemented as necessary. The Geotechnical Engineer should also be retained to provide services during excavation, grading, foundation and construction phases of the work. Observation of footing excavations should be performed prior to placement of reinforcing and concrete to confirm that satisfactory bearing materials are present and is considered a necessary part of continuing geotechnical engineering services for the project. Construction testing, including field and laboratory evaluation of fill, backfill, pavement materials, concrete and steel should be performed to determine whether applicable project requirements have been met. It would be logical for Empire Laboratories, Inc. to provide these additional services for continuing from design through construction and to determine the consistency of field conditions with those data used in our analyses. The analyses and recommendations in this report are based in part upon data obtained from -- the field exploration. The nature and extent of variations beyond the location of test borings may not become evident until construction. If variations then appear evident, it � may be necessary to re-evaluate the recommendations of this report. Our professional services were performed using that degree of care and skill ordinarily exercised, under similar circumstances, by reputable geotechnical engineers practicing in this or similar localities. No warranty, express or implied, is made. We prepared the report as an aid in design of the proposed project. This report is not a bidding document. Any contractor reviewing this report must draw his own conclusions regarding site conditions and specific construction techniques to be used on this project. This report is for the exclusive purpose of providing geotechnical engineering and/or testing information and recommendations. The scope of services for this project does not include, either specifically or by implication, any environmental assessment of the site or identification of contaminated or hazardous materials or conditions. If the owner is concerned about the potential for such contamination, other studies should be undertaken. is I I i Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 3. Downspouts, roof drains or scuppers should discharge into splash blocks or i extensions when the ground surface beneath such features is not protected by exterior slabs or paving. 4. Sprinkler systems should not be installed within 5 feet of foundation walls. Landscaped irrigation adjacent to the foundation system should be minimized i or eliminated. I Additional Design and Construction Considerations: • Exterior Slab Design and Construction: Exterior slabs -on -.grade, exterior architectural features, and utilities founded on, or in backfill may experience some movement due to the volume change of the backfill. Potential movement could be reduced by: • minimizing moisture increases in the backfill • controlling moisture -density during placement of backfill • using designs which allow vertical movement between the exterior features and adjoining structural elements • placing effective control joints on relatively close centers :_..i • allowing vertical movements in utility connections • Underground Utility Systems: All piping should be adequately bedded for proper load distribution. 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 discussed above. Backfill ' should consist of the on -site soils. If on -site bedrock is used, all plus 6-inch material -� should be removed from it prior to its use. The pipe backfill should be compacted t to a minimum of 95 percent of Standard Proctor Density ASTM D698. i • Corrosion Protection: Results of soluble sulfate testing indicate that ASTM Type - 11 Portland cement is suitable for all concrete on and below grade. Foundation concrete should be designed in accordance with the provisions of the ACI Design T Manual, Section 318, Chapter 4. 17 0 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 expected to stand on relatively steep temporary slopes during construction. However, the granular soils may cave and groundwater may also 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. The soils to be penetrated by the proposed excavations may vary significantly across the site. The preliminary soil classifications are based solely on the materials encountered in widely spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions are encountered at the time of construction, the actual conditions should be evaluated to determine any excavation modifications necessary to maintain safe conditions. As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. The exposed slope face should be protected against the elements. Drainage: • Surface Drainage: 1. Positive drainage should be provided during construction and maintained throughout the life of the proposed facility. Infiltration of water into utility or foundation excavations must be prevented during construction. Planters and other surface features which could retain water in areas adjacent to the building or pavements should be sealed or eliminated. 2. In areas where sidewalks or paving do not immediately adjoin the structure, we recommend that protective slopes be provided with a minimum grade of approximately 10 percent for at least 10 feet from perimeter walls. Backfill against footings, exterior walls, and in utility and sprinkler line trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration. 16 I Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 • Fill Materials: 1. Clean on -site soils or approved imported materials may be used as fill material for the following: • general site grading • foundation areas • interior floor slab areas • exterior slab areas • pavement areas • foundation backfill 2. Select granular materials should be used as backfill behind retaining walls. 3. Frozen soils should not be used as fill or backfill. 4. Imported soils (if required) should conform to the following or be approved by the geotechnical engineer: Percent fines by weight Gradation (ASTM C136) 6.. ................... 100 3.. .................. 70-100 No. 4 Sieve .............. .. .............. 50-80 No. 200 Sieve .............................. 60 (max) • Liquid Limit ........................... 30 (max) • Plasticity Index ......................... 15 (max) 5. Aggregate base should conform to Colorado Department of Transportation Class 5 or 6 specifications. • Placement and Compaction: 1. Place and compact fill in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. 2. No fill should be placed over frozen ground. 14 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 2. If excavations penetrate into the bedrock, a large track -mounted backho.e may be needed to advance the excavation. 3. Some additional effort may be necessary to extract boulder sized materials, particularly in deep narrow excavations such as utility trenches. 4. Depending upon depth of excavation and seasonal conditions, groundwater may be encountered in excavations on the site. Pumping from sumps may be utilized to control water within excavations. Well points may be required for significant groundwater flow, or where excavations penetrate groundwater to a significant depth. • Slab Subgrade Preparation: ♦:psi 1. Where existing soils will support floor slab, the soils should be scarified, moisture conditioned and compacted to a minimum depth of 8 inches. 2. A minimum 4-inch layer of clean -graded gravel should be placed beneath slabs. • :Pavement Subgrade Preparation: 1. The subgrade should be scarified, moistened as required, and recompacted for a minimum depth of 8 inches prior to placement of fill and pavement materials. 2. On -site clay soils may pump or become unstable or unworkable at high water contents. Workability may be improved by scarifying and drying. Overexcavation of wet zones and replacement with granular materials may be necessary. Lightweight excavation equipment may be required to reduce subgrade pumping. Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered as a stabilization technique. Laboratory evaluation is recommended to determine the effect of chemical stabilization on subgrade soils prior to construction. 13 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 Earthwork: • Site Clearing: 1. Strip and remove existing vegetation, debris, and other deleterious materials from proposed building and pavement areas. All exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. 2. If unexpected fills or underground facilities are encountered during site clearing, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. Since the area has been used as a railroad depot, the potential exists that additional fill and underground utilities may be encountered. All excavations should be observed by the geotechnical engineer. prior to backfill placement. 3. Stripped materials consisting of vegetation and organic materials should be I�l wasted from the site, or used to revegetate exposed slopes after completion of grading operations. j 4. Demolition of the existing loading dock should include removal of any foundation system. 5. The site should be initially graded to create a relatively level surface to receive fill, and to provide for a relatively uniform thickness of fill beneath proposed building structures. 6. All materials derived from the demolition of existing loading dock should be removed from the site, and not be allowed for use in any on -site fills. 7. All exposed areas which will receive fill, once properly cleared and benched where necessary, should be scarified to a minimum depth of eight inches, conditioned to near optimum moisture content, and compacted. • Excavation: 1. It is anticipated that excavations in the upper subsoils for the proposed construction can be accomplished with conventional earthmoving equipment. 12 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 Since the clay soils on the site have shrink/swell characteristics, pavements could crack in the future. primarily because of expansion 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 performance of all pavements can be enhanced by minimizing excess moisture which can reach the subgrade soils. The following recommendations should be considered at minimum: • Site grading at a minimum 2% grade away from the pavements; • Compaction of any utility trenches for landscaped areas to the same criteria as the pavement subgrade; • Sealing all landscaped areas in, or adjacent to pavements to minimize or prevent moisture migration to subgrade soils; • Placing compacted backfill against the exterior side of curb and gutter; and, • Placing curb, gutter and/or sidewalk directly on subgrade soils without the use of base course materials. Preventative maintenance should be planned, and provided for an on -going pavement management program in order to enhance future pavement performance. Preventative maintenance activities are intended to slow the rate of pavement deterioration, and to preserve the pavement investment. Preventative maintenance consists of both localized maintenance (e.g. crack sealing and patching) and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first priority when implementing a planned pavement maintenance program and provides the highest return on investment for pavements. Recommended preventative maintenance policies for asphalt and jointed concrete pavements, based upon type and severity of distress, are provided in Appendix D. Prior to implementing any maintenance, additional engineering observation is recommended to determine the type and extent of preventative maintenance. 11 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 recommended. The mix design should be submitted prior to construction to verify it adequacy. The asphalt material should be placed in maximum 3-inch lifts, and should be compacted to a minimum of 95% Hveem density (ASTM D1560). Where rigid pavements are used, the concrete should be obtained from an approved mix design with the following minimum properties: • Modulus of Rupture @ 28 days ................. 650 psi minimum • Strength Requirements ....• • • . ASTM C94 ........... • Minimum Cement Content ...................... 6.5 sacks/cu. yd. • Cement Type .................. Type I Portland • Entrained Air Content ........ • • • • • • • •. • • • 6 to 8% • Concrete Aggregate ...........ASTM C33 and CDOT Section 703 • Aggregate Size ............................. 1 inch maximum • Maximum Water Content 0.49 lb/lb of cement • Maximum Allowable Slump .............. 4 inches Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes from time the water is added to the mix. Other specifications outlined by the Colorado Department of Transportation should be followed. .Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation. The location and extent of joints should be based upon the final pavement geometry and should be placed (in feet), at roughly twice the slab thickness (in inches), on center in either direction. Sawed joints should be cut within 24- hours of concrete placement, and should be a minimum of 25 % of slab thickness plus 1 /4 inch. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer. Where dowels cannot be used at joints accessible to wheel loads, pavement thickness should be increased by 25 percent at the joints and tapered to regular thickness in 5 feet. Future performance of pavements constructed on the clay soils at this site will be i dependent upon several factors, including: • maintaining stable moisture content of the subgrade soils; and, j • providing for a planned program of preventative maintenance. t i 10 1 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 Recommended Pavement Section Thickness (inches) Asphalt Plant Mix Portland Traffic Area Alternative Concrete Aggregate Bituminous Cement TOTAL Surface Base Course Base Course Concrete A 3 4 7 B 2 2y, 4%: ile EParking C 5 5 A 3 6 9 B 2 3% 5 h Drive Areas C 6 6 `. Each alternative should be investigated with respect to current material availability and <ssi economic conditions. Aggregate base course (if used. on the site) should consist of a blend of sand and gravel which meets strict specifications for quality and gradation.. Use of materials meeting Colorado Department of Transportation Class 5 or 6 specifications is recommended for base I course. Aggregate base course and select subbase should be placed in lifts and compacted to a minimum of 95% Standard Proctor Density (ASTM D698). Asphalt concrete should be obtained from an approved mix design stating the Hveem properties, optimum asphalt content, job mix formula, and recommended mixing and placing temperatures. Aggregate used in asphalt concrete should meet a particular gradation. Use of materials meeting Colorado Department of Transportation Grading C or CX specification is recommended. The mix design should be submitted prior to construction to verify its adequacy. The asphalt materials should be placed in maximum 3-inch lifts, and should be compacted to a minimum of 95% Hveem density (ASTM D1560). Plant -mixed bituminous base course should be composed of a mixture of aggregate, filler and additives if required, and approved bituminous material. The bituminous base should conform to an approved mix design stating the Hveem properties, optimum asphalt content, job mix formula, and recommended mixing and placing temperatures. Aggregate used in plant -mixed bituminous base course should meet a particVlar gradation. Use of aggregates meeting Colorado Department of Transportation Grading G or C specifications is Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 • Active: Cohesive soil backfill (on -site clays) .................... 40 psf/ft Cohesionless soil backfill (on -site gravels) ................ 30 psf/ft ` • Passive: Cohesive soil backfill (on -site clays) ................... 360 psf/ft Cohesionless soil backfill (on -site gravels) ............... 500 psf/ft • Coefficient of base friction ............................. 0.40 • Adhesion at base of footing ............................ 500 psf Where the design includes restrained elements, the following equivalent fluid pressures are recommended: { • At rest: Ik Cohesive soil backfill (on -site clays) .................... 60 psf/ft Cohesionless soil backfill (on -site gravels) ................ 50 psf/ft j The lateral earth pressures herein are not applicable for submerged soils. Additional 3 recommendations may be necessary if such conditions are to be included in the design. Fill against grade beams and retaining walls should be compacted to densities specified in "Earthwork". High plasticity clay soils should not be used as backfill against retaining walls. Compaction of each lift adjacent to walls should be accomplished with hand operated I tampers or other lightweight compactors. Overcompaction may cause excessive lateral fearth pressures which could result in wall movement. Seismic Considerations: The project site is located in Seismic Risk Zone I of the Seismic Zone Map of the United States as indicated by the Uniform Building Code. Based upon the nature of the subsurface materials, a seismic site coefficient, "s" of 1.0 should be used for the design of structures for the proposed project (Uniform Building Code, Table No. 23-J). Floor Slab Design and Construction: Non -expansive or low -swelling natural soils or engineered fill will support the floor slab. Some differential movement of a slab -on -grade 3 floor system is possible should the subgrade soils become elevated in moisture content. Such movements are considered within general tolerance for normal slab -on -grade } 7 i _ Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 Slab -on -grade construction is considered acceptable for use when subgrade soils consist of the on -site clays and/or gravels, provided that design and construction recommendations 7 are followed. Foundation Systems: Due to the presence of non- to low -swelling soils on the site, spread footing foundations bearing upon undisturbed subsoils and/or engineered fill are 1. recommended for support for the proposed additions. Footings founded on the clay soil or on a structural fill extended to the undisturbed clay stratum may be designed for a maximum bearing pressure of 2,000 psf (dead load plus maximum live load). Footings extended to the granular stratum may be designed for a maximum bearing pressure of 5,000 psf (dead load plus maximum live load). The design bearing pressure may be "f increased by one-third when considering total loads that include wind or seismic conditions. I Existing fill on the site should not be used for support of foundations without removal and j recompaction. Exterior footings should be placed a minimum of 30 inches below finished grade for frost protection. Finished grade is the lowest adjacent grade for perimeter footings. Footings should be proportioned to minimize differential foundation movement. Proportioning on the basis of equal total settlement is recommended; however, I proportioning to relative constant dead -load pressure will also reduce differential settlement between adjacent footings. Total or differential settlement resulting from the assumed structural loads are estimated to be on the order of 3/4 inch. Additional foundation movements could occur if water from any source infiltrates the foundation soils; therefore, proper drainage should be provided in the final design and during construction. It is recommended the proposed addition be constructed structurally independent of the existing building. The influence and interaction of the existing and proposed footings on the foundation soils should be evaluated by the structural engineer. Care should be taken during construction to avoid effecting the foundation of the existing structure. Lateral Earth Pressures: For soils above any free water surface, recommended equivalent fluid pressures for unrestrained foundation elements are: 0 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 Field and Laboratory Test Results: Field and laboratory test results indicate the clay soils exhibit low swell potential and moderate bearing characteristics. The granular soils are nonexpansive and exhibit high bearing characteristics, and the bedrock exhibits very high bearing characteristics. Groundwater Conditions: Groundwater was encountered Borings 1 and 2 at approximate depths of 1 1'/z to 12'% feet in the test borings at the time of field .exploration. The remaining borings were dry at the time of drilling. When checked two days after drilling, f-- groundwater was measured in Borings 3 through 6 at approximate depths of 11'/2 to 13 feet. Borings 1 and 2 were caved at approximate depths of 10 feet. These observations represent only current groundwater conditions, and may not be indicative of other times, or at other locations. Groundwater levels can be expected to fluctuate with .varying seasonal and weather conditions. s Based upon review of U.S. Geological Survey maps ('Hillier, et al, 1983), regional j groundwater is expected to be encountered in unconsolidated alluvial deposits on the site, at depths ranging from 10 to 20 feet below the existing ground surface at the project site. Fluctuations in groundwater levels can best be determined by implementation of a groundwater monitoring plan. Such a plan would include installation of groundwater monitoring wells, and periodic measurement of groundwater levels over a sufficient period of time. The possibility of groundwater fluctuations should be considered when developing design and construction plans for the project. i CONCLUSIONS AND RECOMMENDATIONS _J Geotechnical Considerations: The site appears suitable for the proposed construction. The following foundation systems were evaluated for use on the site: • spread footings bearing on undisturbed soils; and, • spread footings bearing on engineered fill. I l l 'Hillier, Donald E.; Schneider, Paul A., Jr.; and Hutchinson, E. Carter, 1983, Depth to Water Table (1979) in the Boulder -Fort Collins -Greeley Area, Front Range Urban Corridor Colorado, United States Geological Survey, Map 1-855-I. 5 i I Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 causing the uplifting of the Front Range and associated downwarping of the Denver Basin to the east. Relatively flat uplands and broad valleys characterize the present-day topography of the Colorado Piedmont in this region. The site is underlain by the Cretaceous Pierre Formation. The Pierre shale underlies the site at depths of 11 to 14 feet below the surface. The bedrock is overlain by alluvial gravels and clays of Pleistocene and/or Recent Age. Mapping completed by the Colorado Geological Survey ('Hart, 1972), indicates the site in an area of "Low Swell Potential". Potentially expansive materials mapped in this area include bedrock, weathered bedrock and colluvium (surficial units). Soil and Bedrock Conditions: As presented on the Logs of Boring, the subsurface soils are _3 presented as follows: 1 • Existin4 Pavement: Three (3) inches of asphalt were encountered at the surface of Borings 2, 4 and 5. • Fill Material: A layer of fill underlies the pavement in Borings 2, 4 and 5 and the surface of the remaining borings and extends to depths of 1 to 2'% feet below the surface. The fill consists of silty sand with gravel, is moist, and loose to dense. • Sandy Lean Clay: This stratum underlies the fill in Borings 1 through 4 and extends to depths .of 4 to 5 feet below the surface. The sandy lean clay is moist and medium stiff in consistency. • Well -Graded Gravel with Silt Sand Cobbles and Boulders: The gravel stratum extends to the bedrock below. The gravel is dry to wet and loose to extremely dense. It is anticipated that scattered boulders up to 18 inches in diameter will be -� encountered within the gravel stratum. • Sandstone Bedrock: The bedrock was encountered at depths of 11 to 14 feet and extends to greater depths. The upper '/z to 1'/z feet of the bedrock is highly weathered; however, the underlying sandstone is well cemented. �a 'Hart, Stephen S., 1972, Potentially Swelling Sal and Rock in the Front Range Urban Corridor, Colorado, Colorado Geological Survey, Environmental Geology No. 7. 4 I Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 At that time, the field descriptions were confirmed or modified as necessary, an applicable laboratory testing program was formulated to determine engineering properties of the subsurface materials. Boring logs were prepared and are presented in Appendix.A. Selected soil and bedrock samples were tested for the following engineering properties: • Water content • Expansion • Dry density • .Plasticity Index • Consolidation • Water soluble sulfate content • Compressive strength i The significance and purpose of each laboratory test is described in Appendix C. Laboratory test results are presented in Appendix B, and were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. All laboratory tests were performed in general accordance with the applicable ASTM, local or ,17 other accepted standards. SITE CONDITIONS The site consists of the vacant C & S Railroad. Depot which is a single -story, dock height brick structure. A wooden loading dock is located adjacent to the north side of the depot, and several asphalt paved strips are located adjacent to the building. The area is relatively flat and has minor drainage to the north. The area to the west of the depot has been ! levelled and is elevated slightly above the remaining area to the west. An animal grave with gravestone is located near the southwest corner of the property. The site is bordered to the north by Maple Street, to the east by a gravel alley, to the south by LaPorte Avenue and to the west by Mason Street. E SUBSURFACE CONDITIONS Geolocly: The proposed area is located within the Colorado Piedmont section of the Great Plains physiographic province. The Colorado Piedmont, formed during Late Tertiary and Early Quaternary time (approximately 2,000,000 years ago), is a broad, erosional trench which separates the Southern Rocky Mountains from the High Plains. Structurally, the site fj tiJ lies along the western flank of the Denver Basin. During the Late Mesozoic and Early Cenozoic Periods (approximately 70,000,000 years ago), intense tectonic activity occurred, 3 Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 SITE EXPLORATION The scope of the services performed for this project included site reconnaissance by an engineering geologist, a subsurface exploration program, laboratory testing and engineering analysis. Field Exploration: A total of six test borings were drilled on January 4, 1995 to depths of 14'/z feet at the locations shown on the Site Plan, Figure 1. The borings were drilled within the footprint of the proposed building addition and/or possible future expansion. All borings were advanced with a truck -mounted drilling rig, utilizing 4-inch diameter solid and 3 K-inch I.D. hollow stem augers. The borings were located in the field by measurements from the existing building and/or site features. Elevations were taken at each boring location by measurements with an engineer's level from a temporary bench mark (TBM) shown on the Site Plan. The accuracy of boring locations and elevations should only be assumed to the level implied by the methods used. j Continuous lithologic logs of each boring were recorded by the engineering geologist during the drilling operations. During the drilling operations, personnel from Stewart Environmental Consultants, Inc. were also present observing test borings and obtaining soil and groundwater samples for environmental analysis. At selected intervals, samples of the subsurface materials were taken by pushing thin -walled Shelby tubes, or by driving split - spoon samplers. Penetration resistance measurements were obtained by driving the split -spoon into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index to the consistency, relative density or hardness of the materials encountered. 1 Groundwater measurements were made in each boring at the time of site exploration. Groundwater measurements were made in each boring two days after drilling by Stewart I Environmental Consultants, Inc. a i Laboratory Testing: All samples retrieved during the field exploration were returned to the laboratory for observation by the project geotechnical engineer, and were classified in accordance with the Unified Soil Classification System described in Appendix C. Samples L of bedrock were classified in accordance with the general notes for Bedrock Classification. 2 GEOTECHNICAL ENGINEERING REPORT PROPOSED CITY OF FORT COLLINS STORM DRAINAGE DEPARTMENT OFFICE BUILDING FORT COLLINS, COLORADO ELI Project No. 20945281 I January 12, 1995 1 , INTRODUCTION -1 This report contains the results of our geotechnical engineering exploration for the proposed office addition to the existing C & S Depot between Maple Street and LaPorte Avenue east of North Mason Street in downtown Fort Collins, Colorado. The site is located in the Northeast 1 /4 of Section 11, Township 7 North, Range 69 West of the 6th Principal Meridian. The purpose of these services is to provide information and geotechnical engineering s,- <<� recommendations relative to: • subsurface soil and bedrock conditions ;� • groundwater conditions • foundation design and construction • lateral earth pressures • floor slab design and construction • pavement design and construction • earthwork I • drainage 1 The conclusions and recommendations contained in this report are based upon the results of field and laboratory testing, engineering analysis, and experience with similar soil conditions, structures and our understanding of the proposed project. PROPOSED CONSTRUCTION Based on information provided by Mr. Jack Gianola of the City of Fort Collins, the structure will be a single -story, slab -on -grade office addition to the existing C & S Depot. The addition will be placed west, north or south of the existing building: It is anticipated the building will exhibit light wall and column loads and will have masonry wall construction. We assume wall and column loads to be no more than 3 kips per lineal foot and 50 kips, respectively. If heavier loads are anticipated, our recommendations should be reviewed. t It IJ Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 TABLE OF CONTENTS (Cont'd) APPENDIX A Figure No. SitePlan ................................................. 1 Logs of BoringsingsAl thru A6 APPENDIX B .............................. Swell -Consolidation Test . 131 thru B2 Summary of Test Results ............ B3 APPENDIX C: GENERAL NOTES Drilling & Exploration ....................................... C1 Unified Soil Classification .................................... C2 Bedrock Classification, Sedimentary Bedrock ....................... C3 Laboratory Testing, Significance and Purpose ...................... C4 Report Terminology ........................................ C5 APPENDIX D Recommended Preventative Maintenance -Asphalt Concrete Pavements. D1 Recommended Preventative Maintenance -Jointed Concrete Pavements ..... D2 v e M Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 TABLE OF CONTENTS Page No. Letter of Transmittal ............................................... ii . INTRODUCTION ................................................. 1 PROPOSED CONSTRUCTION ....................................... 1 SITE EXPLORATION 2 ............................................. Field Exploration .......................................... 2 Laboratory Testing ......................................... 2 I SITE CONDITIONS .............................................. 3 l SUBSURFACE CONDITIONS ....................................... 3 jGeology 3 ................................................ Soil and Bedrock Conditions .................................. 4 Field and Laboratory Test Results ............................... 5 I, Groundwater Conditions ..................................... 5 CONCLUSIONS AND RECOMMENDATIONS ............................ 5 Geotechnical Considerations ..... ........................... 5 Foundation Systems ......................................... 6 Lateral Earth Pressures ...................................... 6 Seismic Considerations .................................... 7 Floor Slab Design and Construction ............................. 7 Pavement Design and Construction ............................. 8 Earthwork............................................... 12 SiteClearing ........................................ 12 Excavation......................................... 12 Slab Subgrade Preparation ............................... 13 Pavement Subgrade Preparation ........................... 13 Fill Materials ........................................ 14 Placement and Compaction .............................. 14 Compliance 15 Excavation and Trench Construction ........................ 15 16 Drainage ................................................ Surface Drainage ................................... 16. Additional Design and Construction Considerations 17 Exterior Slab Design and Construction ........ :............. 17 ' Underground Utility Systems ............................. 17 Corrosion Protection ................................. 17 18 GENERALCOMMENTS ........................................... ................................. I Geotechnical Engineering Exploration City of Fort Collins Facilities ELI Project No. 20945281 Terracon We appreciated being of service during the geotechnical engineering phase of this project, and are prepared to assist during the construction phases.as well. If you have any questions concerning this report or any of our testing; inspection, design and consulting services, please do not hesitate to contact us. Sincerely, EMPIRE LABORATORIES, INC. A Division of The Terr n mpanies, Inc. ifR.S er i Senior Engineering Geologist J Reviewed by: Larry G. O'Dell, P.E. Office Manager NRS\LGO\cic 4�.X\ %CA HF D _ A1PG y Fo�! 9. SHE4Q�O \`�U1111I a 111ryN/i VO• � ��Y G. '%,,,TNAI Copies to: Addressee (3) Stewart Environmental Consultants, Inc. - Mr. Tom Norman (1) I GEOTECHNICAL ENGINEERING REPORT PROPOSED CITY OF FORT COLLINS STORM DRAINAGE DEPARTMENT OFFICE BUILDING FORT COLLINS, COLORADO ELI PROJECT NO. 20945281 January 12, 1995 Prepared for. CITY OF FORT COLLINS FACILITIES P. 0. BOX 580 FORT COLLINS, COLORADO 80522 ATTN: MR. JACK GIANOLA Prepared by. - Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. i 301 North Howes Fort Collins, Colorado 80521 I I n JAN 1 7 1995 Empire Laboratories, Inc. A Division of The Terracon Companies, Inc.