No preview available
HomeMy WebLinkAboutAddenda - BID - 5821 PEDESTRIAN BRIDGE AND BIKE (4)Administrative Services Purchasing Division CITY OF FORT COLLINS ADDENDUM No. 1 BID #5821 PEDESTRIAN BRIDGE AND TRAIL EXTENSION AT OVERLAND TRAIL ROAD AND CACHE LAPOUDRE RIVER SPECIFICATIONS AND CONTRACT DOCUMENTS Bid No. 5821 — Pedestrian Bridge and Trail Extension at Overland Trail Road and Cache LaPoudre River OPENING DATE: November 6, 2003 — 3:00 p.m. (Our Clock) To all prospective bidders under the specification and contract documents described above, the following changes are hereby made. SPECIFICATIONS 1. Bidder Qualifications — Bidder shall indicate experience in similar types and sizes of work within the past 5 years. Project experience shall specifically include construction of bridge structures (pedestrian and/or roadway) in a river environment, pre -fabricated pedestrian bridges, caisson construction, riverbank protection and stabilization, and general work in a river environment. Provide at least 5 references listing the following: Project Name: Year Completed: Reference Contact: (Name, Agency & Number) Superintendent of Project: 2. City Property Ownership and Construction Easements Exhibit —An 11" x 17" site exhibit map is attached. It depicts areas available for accessing the project site. The staging area location is described in the specifications. Geotechnical Report - Item A Four test borings were originally planned, but only two were actually bored due to site and access conditions at the time of the work. Test Boring No. 1 was the only boring that reached bedrock. Dave Richer, the geotechnical engineer from Terracon who was responsible for the investigation, stated that the results from Test Boring No. 1 could be considered generally indicative of the site. However, there may be some variation in depth to bedrock. He expected 3- to 8-inch cobbles with the possibility of up to 15-inch boulders, but did not expect there to be problems drilling the large diameter caissons through this material. Item B Please note that some copies of the Specifications and Contract Documents are missing pages from the Geotechnical section, so the report is included in its entirety in this Addendum. The Geotechnical Engineering Report by Terracon dated May 6, 2003, and the subsequent addendum letter addressing drilled pier design requirements dated August 18, 2003, is included with this Addendum. 4. Clarification to Section 01500/1 11 Construction Facilities and Temporary Controls Field Offices. Contractor is not required to provide and maintain a temporary office for himself, his subcontractors, or the Owner. However, the Contractor may do so if he so desires at the Contractor's cost. This item was also clarified in Section 01010, Paragraph 1.23A. 5. Modification to Section 01010/1.12A. Summary of Work. Records. The Specification refers to Paragraph 1.12, Field Measurements and Inspection of Surfaces. The reference should be changed to Paragraph 1.11. Page 1 of 2 215 North Mason Street • 2nd Floor • P.O. Box 580 • Fort Collins, CO 80522-0580 • (970) 221-6775 • FAX (970) 221-6707 11 Geotechnical Engineering Exploration . Proposed Pedestrian Bridge Cache La Poudre River @ Overland Trail Road Project No. 20035024 t SITE CONDITIONS Terracon The site for the proposed construction is located southeast of the intersection of the Cache La Poudre River and Overland Trail road north of Fort Collins, Colorado. The river runs southeast and was relatively low during site explorations. However, during our latest site exploration, water levels were higher, thus limiting our access. Several residences are to the north and south and trees border a majority of the river. SUBURFACE CONDITIONS Soil Conditions The subsoils encountered on the bank of the Over, Test Boring No. 1, consisted of an approximate 6-inch layer of silty topsoil underlain by silty clayey sand extending to the silty sand with gravel and/or silty sand with intermittent cobbles extending to the bedrock below. Claystone/siltstone bedrock was encountered at an approximate depth of 20-feet below existing site grade in Test Boring No. 1. The soils encountered within the river, Test Boring No. 4, consisted of silty sand with gravel and cobbles to the maximum depth explored. Field and Laboratory Test Results Field and laboratory test results indicate the granular soils are medium dense to dense in relative density, exhibits non -to -low swell potential and low to moderate load bearing characteristics. The bedrock is weathered to competent, exhibits moderate to high load bearing capabilities and low to moderate swell potential. Groundwater Conditions Groundwater was encountered at an approximate depth of 8-feet below existing site grades in Test Boring No. 1 and approximately 6-inches below existing site grade in Test Boring No. 4 during initial drilling operations. These observations represent groundwater conditions at the time of the field exploration, and may not be indicative of other times. Groundwater levels can be expected to fluctuate with varying seasonal and weather conditions. K, Geotechnical Engineering Exploration Terracon Proposed Pedestrian Bridge Cache La Poudre River @ Overland Trail Road Project No. 20035024 ENGINEERING ANALYSES AND RECOMMENDATIONS Geotechnical Considerations Foundation Systems — Spread Footings The proposed bridge structure may be supported by conventional type spread footings bearing upon the undisturbed native granular soils extended below the river channel. The footings should be designed for a net allowable bearing pressure of 2,500 psf. Footings should be placed a minimum of 42-inches below final grade for frost protection and to provide confinement for the bearing soils. In addition, the footings should be constructed below anticipated scour depth or scour countermeasures should be provided in the design. Footings should be proportioned to reduce differential foundation movement. Proportioning on the basis of equal total settlement is recommended; however, proportioning to relative constant dead -load pressure will also reduce differential settlement between adjacent footings. Total settlement resulting from the assumed structural loads is estimated to be on the order of 1-inch or less. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. Lateral Earth Pressures For soils above any free water surface, recommended equivalent fluid pressures for unrestrained foundation elements are: • Active: Cohesionless soils (on -site sand or imported material) .......... 35 psf/ft • Passive: Cohesionless soils (on -site sand or imported material) ........ 300 psf/ft • Coefficient of Base Friction...................................................0.45* psf *The coefficient of base friction should be reduced to 0.30 when used in conjunction with passive pressure Where the design includes restrained elements, the following equivalent fluid pressures are recommended: • At rest: 4 I' Geotechnical Engineering Exploration Terracon Proposed Pedestrian Bridge 1 Cache La Poudre River @ Overland Trail Road Project No. 20035024 ICohesionless soils (on -site sand or imported material) .......... 55 psf/ft For soils below any free water surface (submerged soils/hydrostatic loading), recommended 1 equivalent fluid pressures for unrestrained foundation elements are: • Active: ICohesionless soils (on -site sand or imported material) .......... 80 psf/ft • Passive: ICohesionless soils (on -site sand or imported material) ........150_ psf/ft At rest: ' ICohesionless soils (on -site sand or imported material) .......... 90 psf/ft Fill against retaining walls should be compacted to densities specified in Earthwork. Compaction of each lift adjacent to walls should be accomplished with hand -operated tampers or other lightweight compactors. Overcompaction may cause excessive lateral earth 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 1997 Uniform Building Code. Based upon the nature of the subsurface Imaterials, a soil profile type Sc should be used for the design of structures for the proposed project (1997 Uniform Building Code, Table No. 16-J). IEarthwork IGeneral Considerations The following presents recommendations for site preparation, excavation, subgrade Ipreparation and placement of engineered fills on the project. All earthwork on the project should be observed and evaluated by Terracon. The I evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, foundation bearing soils, and other geotechnical conditions exposed during the construction of the project. • Site Preparation IThe 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. ' 5 Geotechnical Engineering Exploration Terracon Proposed Pedestrian Bridge Cache La Poudre River @ Overland Trail Road Project No. 20035024 1 All exposed areas which will receive fill, once properly cleared and benched where necessary, should be scarified to a minimum depth of 12-inches, conditioned to near optimum moisture content, and compacted. It is anticipated that excavations for the proposed construction can be accomplished with conventional earthmoving equipment. 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. Fill Materials and Placement Clean on -site soils or approved imported materials may be used as fill material and are suitable for use as compacted fill. Imported granular soils (if required) should conform to the following: Gradation Percent finer by weight (ASTM C136) 6"..........................................................................................................100 3"..................................................................................................... 70-100 No. 4 Sieve.............................................................. ....................... 40-100 No. 200 Sieve...............................................................................30 (max) • Liquid Limit.......................................................................30 (max) • Plasticity Index............................................10 (max) to non -plastic Engineered fill should be placed and compacted in horizontal lifts, using equipment and procedures that will produce recommended moisture contents and densities throughout the lift. It is recommended all fill material be compacted to a minimum 95 percent of Standard Proctor Density ASTM D698. On -site soils for backfill or grading purposes should be compacted within a moisture content range of 2 percent below, to 2 percent above optimum. Imported granular soils should be compacted within a moisture range of 3 percent below to 3 percent above optimum unless modified by the project geotechnical engineer. 9 Geotechnical Engineering Exploration Terracon Proposed Pedestrian Bridge Cache La Poudre River @ Overland Trail Road Project No. 20035024 • Excavation and Trench Construction Excavations into the on -site soils may encounter caving soils and groundwater, depending upon the final depth of excavation. 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. Additional Design and Construction Considerations Underground Utility Systems All piping should be adequately bedded for proper load distribution. It is suggested that clean, graded gravel compacted to 75 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 discussed above. Backfill should consist of the on -site . soils or imported material approved by the geotechnical engineer. The pipe backfill should be compacted to a minimum of 95 percent of Standard Proctor Density ASTM D698. Corrosion Protection ASTM Type I Portland cement is suitable for all concrete on and below grade. However, if there is no, or minimal cost differential, use of ASTM Type II Portland cement is recommended for additional sulfate resistance of construction concrete. Foundation 7 Geotechnical Engineering Exploration Proposed Pedestrian Bridge Cache La Poudre River @ Overland Trail Road Project No. 20035024 Terracon concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. GENERAL COMMENTS Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide testing and observation during excavation, grading, foundation and construction phases of the project. The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that, further evaluation and supplemental recommendations can be provided. The scope of services for this project does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken. 1 This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical I engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing. l . it D v m a X I , FIGURE 1: SITE PLAN LEGENDPROPOSED BRIDGE L;;N ERLAND TRAIL ROAD & POUDRE RNER APPROXIMATE FORTCOLLINS,COLORADO TEST BORING LOCATION lrerracan DAR Chsckee DAR 301 N. Howes Sired VF=jpnN. 1FNDg AA LOCATON ONLY. FARCONSTRUCTION Appiova4 BY• DAR Fort Collins. Cobredo 80521 PURPOSES. Fb Nenw: 2003502¢1 1 LOG OF BORING NO. 1 CLIENT ARCHITECT/ENGINEER Page 1 of 1 Ayres and Associates SIT�ache La Poudre River @Overland Trail Road PROJECT Fort Collins, Colorado Proposed Pedestrian Bridge Boring Location: North River Bank SAMPLES TESTS 0 0 m C W DESCRIPTION > e w U } w � Z� a = W > z(n ofW Z Zz W D D_ W a0 K U, 0 0Ui n Z tr d-i mm �U 0 a Z� Cl)j ' /. .� 0.5 6" TOPSOII I an, gray, brown, moist to wet, medium dense *Intermittent Dense Cobble Lenses 1 AC O:. Encountered 5 l 10 1 17 SILTY SAND Tan, gray, brown, wet, medium dense 20 WEATHERED CLAYSTONFJSILTSTONE 22.5 Gray, moist, moderately hard x x CLAYSTONEISILTSTONE x x Gray, moist, hard to very hard I x x x x x x x x I x x x x x x x x x n x x x x x x Qx x 29.7 a BOTTOM OF BORING aU WR F q The stratification lines represent the appropmate boundary lines 8 H between soil and rock types: in -situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft �W W L 4-80 WD I 1rerracon = WL Y WL Initial Water Level Reading BORING STARTED 4-16-03 BORING COMPLETED 4-16-03 RIG CME-751 FOREMAN DRL APPROVED DAR I JOB # 20035024 LOG OF BORING NO. 4 page 1 of 1 CLIENT ARCHITECT/ENGINEER Awes and Associates SITICache La Poudre River @ Overland Trail Road PROJECT Fort Collins, Colorado Boring Location: South River Bank k7 DESCRIPTION U S 0 Tan, gray, brown, moist to wet, medium dense ' Intermittent Dense Cobble Lenses Encountered AUGER Pedestrian SAMh'LtS TESTS m c O ii } w F H w zF 2 ILO) w 020 > W 0 ZVJ 3 ofW Z ZZ 0W w a w a- ¢0 o Z� o D Z wm 3� o a Drn 5 1 The stratification lines represent the approximate boundary lines between soil and rock types: in -situ, the transition may be gradual. WATER LEVEL OBSERVATIONS, ft RING STARTED 4-2-03 WL 0 5 WD � lrerracon[RlING COMPLETED 4-2-03 WL 5L y CME 45 FOREMAN ASRWL Initial Water Level Reading ROVED DAR I JOB # 20035024 6. Clarification to Section 01010/1.09D Summary of Work Regulatory Requirements and Section 02140/3.02, Water Control, Water Quality. A construction dewatering and groundwater discharge permit is required from the State of Colorado. Contractor shall submit application for this permit, and others that are time sensitive, upon Notice of Award. The permit typically takes approximately one month to obtain if prepared properly. Construction cannot begin onsite until the permit is obtained. 7. Clarification to Section 02140/3.01 D. Engineer will provide 100-year flow rate, depths, velocities, and floodplain limits if requested by the Contractor. ATTACHMENTS 1. Geotechnical Engineering Report Terracon Project No. 20035024 May 6, 2003 Total Page(s) - 26 2. Geotechnical Addendum Letter Terracon August 18, 2003 Total Page(s) - 4 3. City Property Ownership and Construction Easements Exhibit 8'r X 11" exhibit Total Page(s) - 1 If you should have any questions, please contact Jason Stutzman, P.E., Project Manager at (970) 221-6366, John Stephen, CPPO, Senior Buyer at (970) 221-6777 or Chris Carlson, P.E., C.F.M., Consultant Engineer at (970)223-5556. RECEIPT OF THIS ADDENDUM MUST BE ACKNOWLEDGED BY A WRITTEN STATEMENT ENCLOSED WITH THE BID/QUOTE STATING THAT THIS ADDENDUM HAS BEEN RECEIVED. Page 2 of 2 D -a CD Q X u GENERAL NOTES DRILLING & SAMPLING SYMBOLS: SS: Split Spoon - 1 3/8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin -Walled Tube - 2" O.D., unless otherwise noted PA Power Auger RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger DB: Diamond Bit Coring - 4", N, B RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary The number of blows required to advance a standard 2-inch O.D. split -spoon sampler (SS) the last 12 inches of the total 18- inch penetration with a 140-pound hammer falling 30 inches is considered the 'Standard Penetration' or 'N-value'. For 3' O.D. ring samplers (RS) the penetration value is reported as the number of blows required to advance the sampler 12 inches using a 140-pound hammer failing 30 inches, reported as 'blows per foot," and is not considered equivalent to the "Standard Penetration' or'N-value". WATER LEVEL MEASUREMENT SYMBOLS: WL: Water Level WS: While Sampling WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal Water levels indicated on the boring logs are the levelsmeasured in the borings at'the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils„the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels may not be possible with only short- term observations. DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse -grained soils are defined on the basis of their in -place relative density and fine-grained soils on the basis of their consistency. FINE-GRAINED SOILS COARSE -GRAINED SOILS BEDROCK RS (SS) fRS) SS Relative fRS) fSS) , Blows/Ft: Blows/Ft. Consistency Blows/Ft. Blows/Ft. Densit Blows/Ft. Blows/Ft. Consistency < 3 < 2 Very Soft 0-6 < 3 Very Loose < 30 < 20 Weathered 3-4 2-3 Soft 7-18 4-9 Loose 301t9 20-29 Firm 5-9 4-6 Medium Stiff 19-58 10-29 Medium Dense 50-89 30A9 Medium Hard 10-18 7-12 Stiff 59-98 30-49 Dense 90-119 50-79 Hard 19-42 13-26 Very Stiff > 98 > 49 Very Dense > 119 > 79 Very Hard > 42 > 26 Hard RELATIVE PROPORTIONS OF SAND AND GRAVEL Descriptive Terms of Percent of Other Constituents Dry Weight GRAIN SIZE TERMINOLOGY Major Component of Sample Particle Size Trace < 15 . Boulders Over 12 in. (300mm) With 15 — 29 Cobbles 12 in. to 3 in. (300mm to 75 mm) Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm) Sand #4 to #200 sieve (4.75mm to 0.075mm) Silt or Clay Passing #200 Sieve (0.075mm) RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION Descriptive Terms of Percent of Other Constituents Dry Weight Term Plasticity Index Trace < 5 Non -plastic 0 With 5-12 Low 1-10 Modifiers > 12 Medium 11-30 High 30+ 11%=1 I cJa_ul I UNIFIED SOIL CLASSIFICATION SYSTEM Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests4 Coarse Grained Soils Gravels Clean Gravels Cu Z 4 and 1 5 Cc:5 3E More than 50% retained More than 50% of coarse Less than 5% fines` Cu < 4 and/or 1 > Cc > 3E fraction retained on on No. 200 sieve No. 4 sieve Gravels with Fines More Fines classify as ML or MH than 12% fires` Fines classify as CL or CH Sands Clean Sands Cu 2 6 and 1 5 Cc:5 3E 50% or more of coarse Less than 5% fines Cu < 6 and/or 1 > Cc > 3E fraction passes No. 4 sieve Sands with Fines Fines classify as ML or MH More than 12% fines' Fines classify as CL or CH Fine -Grained Soils Silts and Clays inorganic 50% or more passes the Liquid limit less than 50 No. 200 sieve _ organic Sifts and Clays inorganic Liquid limit 50 or more organic PI > 7 and plots on or above "A" line'' PI < 4 or plots below "A" line Soil Classification Group Symbol Group Name° GW Well graded graveiF GP Poorly graded gravel" GM Silty graVelFA H GC Clayey gravelF•O-" SW SP Well graded sand' Poorly graded sand' SM Silty sandOx' SC Clayey sandGA' CL Lean dayKL-" ML SikK4" Liquid limit -oven Organic clayK4" 1_-_1 <0.75 OL Liquid limit - not organic sieLMO dried PI plots on or above 'A" line PI plots below "A" line CH Fat cWL." MH Elastic sift"" Liquid limit - oven dried Organic dajAL,'" <0.75 OH Liquid limit - not dried Organic siftKLAO Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat "Based on the material passing the 34n. (75-mm) sieve e If field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. O Gravels with 5 to 12% fines require dual symbols: GW-GM well graded gravel with sift, GW-GC well graded gravel with day, GP -GM poorly graded gravel with sift, GP -GC poorly graded gravel with day. ° Sands with 5 to 12% fines require dual symbols: SW-SM well graded sand with sift, SW -SC well graded sand with day, SP-SM poorly graded sand with sift, SP-SC poorly graded sand with day z ECU = DwrD10 Cc = (1330) Dto K Dso F If Sa contains z 15% sand, add'with sand" to group name. olf fines classify as CL-ML, use dual symbol GC -GM, or SC-SM. a- 4", 10 7 4 "If fines are organic, add "with organic fines" to group name. If soil contains 215% gravel, add `with graver to group name. If Atterberg Omits plot in shaded area, soil is a CL-ML, silty clay. K If sal contains 15 to 29% plus No. 200, add 'with sand" or "with gravel," whichever is predominant. L If soil contains 2 30% plus No. 200 predominantly sand, add "sandy" to group name. "" If sal contains 2 30% plus No. 200, predominantly gravel, add 'gravely' to group name. "PI z 4 and plots on or above "A' line. Opt < 4 or plots below "A' line. "PI plots on or above'A' fine. GPI plots below'A' line. For classification of fine-grained ' soils and fine-grained fraction of coarse -grained soils ! Jae Equation of A" - line +J , •A Horizontal at PIy1 to LL=25.5. then PI--0.73 (LL-20) o` Q\ Equation a'v'- fine Vertical at LL=16 to PI=7, • G VW PI=0.9 (LL-6) . i OL MH or OH ' ML or OL 0 0 10 16 20 30 40 50 60 70 so LIQUID LIMIT (LL) 90 100 110 rerracon_ 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 or pre-existing rocks derived by mechanical weathering, evaporation or by chemical or organic origin. The sediments are usually indurated by cementation or compaction. Chert Very fine-grained siliceous rock composed of micro -crystalline or. cryptocrystalline 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 and may contain carbonate minerals. 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)2). May contain non -carbonate impurities such as quartz, chert, day 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 non -carbonate impurities such as quartz, chert, clay minerals, organic matter, gypsum and sulfides. Reacts with hydrochloric acid (HCL). 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 days or any rock containing clay. Shale is hard, platy, of fissile may be gray, black, reddish or green and may contain some carbonate minerals (calcareous shale). Siltstone Fine grained rock composed of or derived by erosion of silts or rock containing silt. Siltstones consist predominantly of silt sized particles (O.Q625 to 0.002 mm in diameter) and are intermediate rocks between .claystones and sandstones and may contain carbonate minerals. 1fe ROCK CLASSIFICATION (Based on ASTM C-294) Metamorphic Rocks Metamorphic rocks form from igneous, sedimentary, or pre-existing metamorphic rocks in response to changes in chemical and physical conditions occurring within the earth's crust after formation of the original rock. The changes may be textural, structural, or mineralogic and may be accompanied by changes in chemical composition. The rocks are dense and may be massive but are more frequently foliated (laminated or layered) and tend to break into platy particles. The mineral composition is very variable depending in part on the degree of metamorphism and in part on the composition of the original rock. Marble A recrystallized medium- to coarse -grained carbonate rock composed of calcite or dolomite, or calcite and dolomite. The original impurities are present in the form of new minerals, such as micas, amphiboles, pyroxenes, and graphite. Metaquartzite A granular rock consisting essentially of recrystallized quartz. Its strength and resistance to weathering derive from the.intedocking of the quartz grains. Slate A fine-grained metamorphic rock that is distinctly laminated and tends to split into thin parallel layers. The mineral composition usually cannot be determined with the unaided eye. Schist A highly layered rock tending to split into nearly parallel planes (schistose) in which the grain is coarse enough to permit identification of the principal minerals. Schists are subdivided into varieties on the basis of the most prominent mineral present in addition to quartz or to quartz and feldspars; for instance, mica schist. Greenschist is a green schistose rock whose color is due to abundance of one or more of the green minerals, chlorite or amphibole, and is commonly derived from altered volcanic rock. Gneiss One of the most common metamorphic rocks, usually formed from igneous or sedimentary rocks by a higher degree of metamorphism than the schists. It is characterized by a layered or foliated structure resulting from approximately parallel lenses and bands of platy minerals, usually micas or prisms, usually amphiboles, and of granular minerals, usually quartz and feldspars. All intermediate varieties between gneiss .and schist and between gneiss and granite are often found in the same areas in which well-defined gneisses occur. 1 ROCK CLASSIFICATION (Based on ASTM C-294) Igneous Rocks Igneous rocks are formed by cooling from a molten rock mass (magma). Igneous rocks are divided into two classes (1) plutonic, or intrusive, that have cooled slowly within the earth; and (2) volcanic, or extrusive, that formed from quickly cooled lavas. Plutonic rocks have grain sizes greater than approximately 1 mm, and are classified as coarse- or medium -grained. Volcanic rocks have grain sizes less than approximately 1 mm, and are classified as fine-grained. Volcanic rocks frequently contain glass. Both plutonic and volcanic rocks may consist of porphyries that are characterized by the presence of large mineral grains in a fine-grained or glassy groundmass. This is the result of sharp changes in rate of cooling or other physio-chemical conditions during solidification of the melt. Granite Granite is a medium- to coarse -grained light-colored rock characterized by the presence of potassium feldspar with lesser amounts of plagioclase feldspars and quartz. The characteristic potassium feldspars are orthoclase or microcline, or both; the common plagioclase feldspars are albite and oligoclase. Feldspars are more abundant than quartz. Dark -colored mica (biotite) is usually present, and light-colored mica (muscovite) is frequently present. Other dark -colored ferromagnesian minerals, especially homblende, may be present in amounts less than those of the light-colored constituents. Quartz-Monzonite Rocks similar to granite but contain more plagioclase feldspar than potassium and Grano -Diorite feldspar. Basalt Fine-grained extrusive equivalent of gabbro and diabase. When basalt contains natural glass, the.glass is generally lower in silica content than that of the lighter - colored extrusive rocks. ,I re LABORATORY TEST SIGNIFICANCE AND PURPOSE TEST SIGNIFICANCE PURPOSE California Bearing Used to evaluate the potential strength of subgrade soil, Pavement Thickness Ratio subbase, and base course material, including recycled Design materials for use in road and airfield pavements. Consolidation Used to develop an estimate of both the rate and amount Foundation Design of both differential and total settlement of a structure. Direct Shear Used to determine the consolidated drained shear strength Bearing Capacity, of soil or rock. Foundation Design, and Slo . e Stability Dry Density Used to determine the in -place density of natural, Index Property Soil inorganic, fine-grained soils. Behavior Expansion Used to measure the expansive potential of fine-grained Foundation and Slab soil and to provide a basis for swell potential classification. Design Gradation Used for the quantitative determination of the distribution Soil Classification of particle sizes in soil. Liquid & Plastic Limi> Used as an integral part of engineering classification Soil Classifcadon Plasticity Index systems to characterize the fine-grained fraction of soils, and to specify the fine-grained fraction of construction materials. Permeability Used to determine the capacity of soil or rock to conduct a Groundwater Flow liquid or gas. Analysis pH Used to determine the degree of acidity or alkalinity of a Corrosion Potential soil. Resistivity Used to indicate the relative ability of a soil medium to Corrosion Potential carry electrical currents. R-Value Used to evaluate the potential strength of subgrade soil, Pavement Thickness subbase, and base course material, including recycled Design materials for use in road and airfield pavements. Soluble Sulfate Used to determine the quantitative amount of soluble Corrosion Potential sulfates within a soil mass. Unconfined To obtain the approximate compressive strength of soils Bearing Capacity Compression that possess sufficient cohesion to permit testing in the Analysis for unconfined state. I Foundations Water Content Used to determine the quantitative amount of water in a Index Property Soil soil mass. Behavior Irerraco REPORT TERMINOLOGY (Based on ASTM D653) Allowable Soil The recommended maximum contact stress developed at the interface of the foundation Bearing Capacity 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 slabs or Course 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 A concrete foundation element cast in a circular excavation which may have an enlarged Pier or Shaft) 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 shear stress Friction at which sliding starts between the two surfaces. Colluvium 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 typically used Grade as a floor system. Differential Unequal settlement or heave between, or within foundation elements of structure. Movement Earth Pressure The pressure 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 liy 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 throughout the action of man prior to exploration of the site. Man -Made Fill Existing Grade The ground surface at the time of field exploration. rerracon REPORT TERMINOLOGY (Based on ASTM D653) Expansive The potential of a soil to expand (increase in volume) due to absorption of moisture. Potential Finished Grade The final grade created as a part of the project. Footing A portion of the foundation of a structure that transmits loads directly to the soil. Foundation The lower part of a structure that transmits the loads to the soil or bedrock. Frost Depth The depth at 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 occurring 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 weight by a Content given compactive effort. Perched Water Groundwater, usually of limited area maintained above a normal water elevation by the presence of an intervening relatively impervious continuous 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 the structure such as a Shear) drilled pier. 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 chahge 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. - 1rerracon 9 August 18, 2003 Ayres Associates 3665 JFK Parkway Building 2 — Suite 200 Fort Collins, Colorado 80527 Attn: Chris Carlson Irerracon 301 N. Howes • P.O. Box 503 Fort Collins. Colorado 80521-0503 (970) 484.0359 Fax (970) 484-0454 Re: Geotechnical Engineering Report —Addendum No.1 (Drilled Piers) Proposed Pedestrian Bridge Cache La Poudre River at Overland Trail Road Larimer County, Colorado Terracon Project No. 20035024 Terracon completed a geotechnical engineering exploration for the proposed pedestrian bridge to span the Cache La Poudre River near the river's intersection with Overland Trail Road north of Fort Collins, Colorado. Terracon submitted a "Geotechnical Engineering Report" dated May 6, 2003, in which conventional type spread footings were recommended. However, after further review and consultation with the projects structural engineer • and the City of Fort Collins Park Planning Department, a deep foundation system, such as drilled piers/caissons are required due to the potential for scour and erosional effects: Therefore, the following information provides the appropriate foundation design recommendations for the use of drilled piers based on the on -site subsurface conditions. Soil and Bedrock Conditions The subsoils encountered on the bank of the river, in Test Boring No. 1, consisted of an approximate 6-inch layer of silty topsoil underlain by silty clayey sand extending to the coarse silty sand with gravel and/or silty sand with intermittent cobbles extending to the bedrock below. Claystone/siltstone bedrock was encountered at an approximate depth of 20-feet below existing site grade in Test Boring No. 1. The soils encountered within the river, Test Boring No. 4, consisted of silty sand with gravel and cobbles to the maximum depth explored, where auger refusal was encountered. Groundwater was encountered at an approximate depth of 8-feet below existing site grades in Test Boring No. 1 and approximately 6-inches below existing site grade in Test Boring No. 4 during initial drilling operations. Geotechnical Engineering Recommendations — Drilled Piers Straight shaft piers, drilled a minimum of 5-feet into competent or hard claystone/siltstone bedrock are recommended for support of the proposed structure. For axial compression loads, piers may be designed for a maximum end -bearing pressure of 30,000 pounds per square foot (psf), and a skin friction of 3,000 psf for the portion of the pier in the competent bedrock stratum. All piers require sufficient dead -load and/or additional penetration into the bearing strata to resist the potential uplift of the expansive materials. All piers should be designed for a minimum dead -load pressure of 5,000 psf, based upon pier end area. Arizona ■ Arkansas ■ Colorado ■ Georgia ■ Idaho ■ Illinois ■ Iowa ■ Kansas ■ Kentucky ■ Minnesota ■ Missouri Montana ■ Nebraska ■ Nevada ■ New Mexico ■ Oklahoma ■ Tennessee ■ Texas ■ Utah ■ Wisconsin ■ Wyoming Quality Engineering Since 1965 GEOTECHNICAL ENGINEERING REPORT PROPOSED PEDESTRIAN BRIDGE CACHE LA POUDRE RIVER AT OVERLAND TRAIL ROAD FORT COLLINS, COLORADO TERRACON PROJECT NO. 20035024 MAY 6, 2003 Irerracon Geotechnical Engineering Report —Addendum No. 1 Cache La Poudre — Pedestrian Bridge Overland Trail, Larimer County, Colorado Project No. 20035024 Page 2 Terracon A minimum practical horizontal spacing between piers of at least three (3) diameters should be maintained, and adjacent piers should bear at about the same elevation. Piers should be considered to work in-group action if the horizontal spacing is less than three pier diameters. The capacity of individual piers may need to be reduced when considering the effects of group action. Capacity reduction is a function of pier spacing and the number of piers within a group. If group action analyses are necessary, capacity reduction factors can be provided. All piers require sufficient dead load and/or additional penetration into the bearing strata to resist potential uplift of the expansive materials. To satisfy forces in the horizontal direction, for a pier diameter of 12 inches, piers may be designed for lateral loads using a modulus of 100 tons per square foot, (tsf) for any portion of the pier in the overburden soils, and 350 tsf in the siltstone/claystone bedrock formation. The coefficient of subgrade reaction for varying pier diameters is as follows: The soil modulus and coefficient of subgrade reaction are ultimate values; therefore, appropriate factors of safety should be applied in the pier design. When the lateral capacity of drilled piers is evaluated by the L-Pile (COM 624) computer program, we recommend that intemally generated load -deformation (P-Y) curves be used. The following parameters may be used for the design of laterally loaded piers, using the L-Pile (COM 624) computer program: Unit Weight of Soil (PCF) 130 115i") 65(1) Cohesion (psf) 0 1500 5000 Angle of Internal Friction 0 35 23 0 (degrees) Strain Corresponding to % Max. — 0.02 0.015 Principal Stress Difference W *Notes: 1) Use of 65 PCF below the water table Geotechnical Engineering Report —Addendum No. 1 Cache La Poudre — Pedestrian Bridge Overland Trail, Larimer County, Colorado Project No. 20035024 Page 3 Terracon All piers should be reinforced full depth for the applied axial, lateral and uplift stresses imposed. The amount of reinforcing steel for expansion should be determined by the tensile force created by the uplift force on each pier, with allowance for dead load. Minimum reinforcement of at least one-half percent of the cross -sectional area of each pier should be specified. To reduce potential uplift forces on piers, use of long grade beam spans to increase individual pier loading is recommended. For this project, a minimum pier diameter of 18-inches is recommended. Drilling to design depths should be possible with conventional single flight power augers. However interbedded cemented sandstone/siltstone lenses may be encountered at increased depths and may require the use of specialized equipment to achieve designed lengths. Groundwater conditions indicate that temporary steel casing will likely be required to properly drill and clean piers prior to concrete placement. Groundwater was encountered at approximate depths of % to 8-feet below existing site grades. Groundwater should be removed from each pier hole prior to concrete placement. Pier concrete should be placed immediately after completion of drilling and cleaning. If pier concrete cannot be placed in less than 3 inches of water, a tremie should be used for concrete placement up to a maximum of 6-inches of water. Due to potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric volumes. Casing should be withdrawn in a slow continuous manner maintaining a sufficient head of concrete to prevent infiltration of water or the creation of voids in pier concrete. Pier concrete should have a relatively high fluidity when placed in cased pier holes or through a tremie. Pier concrete with a slump in the range of 6 to 8-inches is recommended. Free -fall concrete placement in piers will only be acceptable if provisions are taken to avoid striking the concrete on the; sides of the hole or reinforcing steel. The use of a bottom -dump hopper, or tremie discharging near the bottom of the hole where concrete segregation will be minimized, is recommended. To provide increased resistance to potential uplift forces, the sides of each pier should be mechanically roughened in the bearing strata. This should be accomplished by a roughening tooth placed on the auger. Pier bearing surfaces must be cleaned prior to concrete placement. A representative of the geotechnical engineer should inspect the bearing surface and pier configuration and the foundation excavations. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. Geotechnical Engineering Report —Addendum No. 1 Cache La Poudre — Pedestrian Bridge Overland Trail, Larimer County, Colorado Project No. 20035024 Page 4 Terracon We appreciate the opportunity to be of service to you on this phase of your project. If you have any questions concerning this report, or if we may be of further service to you, please do not hesitate to contact us. Sincerely, David A. Rice Geotechnical Copies to: Manager Addressee (5) City of Fort Collins — Park Planning Department (1): Mr. Jason Stutzman w I � w W W w N • �� S 410 a� al O � FJ-1 E-1 2 Ula 4O �W 4, UJ w WILL ONVN18A0 "Y F w W ® II 04 0. OCTOBER 21, 2003 CITY OF FORT COLLINS PLANHOLDERS LIST FOR BID #5821 PEDESTRIAN BRIDGE & BIKE TRAIL EXTENSION AT OVERLAND TRAIL RD. & CACHE LA POUDRE RIVER R C HEATH P O DRAWER H FT. COLLINS, CO 80522 PH 970-221-4195 FAX 970-221-2907 NORTHSTAR CONCRETE POBOX Y BERTHOUD, CO 80513 PH 970-532-0805 FAX 970-532-4682 NARANJO CIVIL CONSTRUCTION 1863 2ND AVE. GREELEY, CO 80631 PH 970-356-7909 FAX 970-356-0887 ECI SITE CONSTRUCTION P O BOX 2135 LOVELAND, CO 80539 PH 970-669-6291 FAX 970-669-6411 G L HOFF P O BOX 7448 LOVELAND, CO 80532-7448 PH 970-669-3255 FAX 970-663-1566 EAGLE SPAN STEEL STRUCTURES 102 W 4T" ST LOVELAND, CO 80537 PH 970-593-0596 FAX 970-593-0583 CARNES P O BOX 1258 WELLINGTON, CO 80549 PH 970-56&8632 FAX 970-568-3165 TARCO 1401 RIVERSIDE, SUITE 3 FT. COLLINS, CO 80525 PH 970-493-9006 FAX 970-493-9022 ALL ABOUT SAFETY 12607 WCR 76 EATON, CO 80615 PH 970-686-6644 FAX 970-686-6059 UNITED RENTAL 2456 E 9T" ST LOVELAND, CO 80537 PH 970-667-3620 FAX 970-667-3930 MEZA CONSTRUCTION 740 S BRYANT ST DENVER, CO 80202 PH 303-778-8381 FAX 720-570-1894 EDWARD KRAEMER & SONS 680 ATCHINSON WAY, SUITE 500 CASTLE ROCK, CO 80104 PH 303-688-7500 FAX 303-688-8811 VOGEL CONCRETE 1313 BLUE SPRUCE DR., SUITE B PH 970-484-3880 FAX 970-407-9484 LEFT HAND EXCAVATING 3756 EUREKA WAY FREDERICK, CO 80516 PH 303-833-3326 FAX 303-833-3353 Bid #5821 Page 2 MOUNTAIN CONSTRUCTORS P O BOX 405 PLATTEVILLE, CO 80651 PH 970-785-6161 FAX 970-785-2515 EXPRESS CONCRETE 5305 ZIEGLER RD FT. COLLINS, CO 80528 PH 970-225-1287 FAX 970-229-0800 ATTENDANCE RECORD PRE CONFERENCE Project: Bid #5821 PEDESTRIAN BRIDGES & BIKE TRAIL EXTENSION AT OVERLAND TRAIL ROAD AND CACHE LA POUDRE RIVER Time: 10:OOA.M. Date: OCTOBER 16, 2003 Location: 215 N. MASON, 3 rd FLOOR, 36 NAME FIRM NAME ADDRESS TELEPHONE FAX # E-MAIL ADDRESS IG�rZCoHy3-yo�a J© a) -55- J-,o�el�4 � �� q70- (2&q-(zg ��y-��t T � GAS t 13 YM G ; O'► G I k tt"la- �xt.dow� pp. w 4L-am 9 7e C=-t> BVIL sic 1ZC � eOrisT. <L A::f- C04'-LNs Co broS �/4 ZZ!-`11cl-'r ��a 3 Zzi-z9a Q7a -34 bo �lkerl- C-cNs rGv c77 (- �u)a, STEAR�S �,AGL&5PA•) Sr6ec Sm. loz w. 4�= i,w��a��CQ 40537 Q-7o 5q� s— 59� sY3 -vsg3 r�STEaR,,S �EAl�E5PAti1. /-r�jtr cet i ¢84--a3 5 # d1-.5 C Ha/7��-1g.V �o ��a�*11N �N l�Yr�9_5� aaI-/077'7 aa1-�707 Q reb 45-5-0c-"a s .ytiK $oszs- cl-70 aa�-ssS>o q70 �0?3- sS78 Ca.isonc@a��o�� � motes. /, rN (l ZK ff tisl r w co xr� a a 8 83 ki CVkeu-(P ctwc� sir�c Oom en GEOTECHNICAL ENGINEERING REPORT PROPOSED PEDESTRIAN BRIDGE CACHE LA POUDRE RIVER AT OVERLAND TRAIL ROAD FORT COLLINS, COLORADO TERRACON PROJECT NO. 20035024 MAY 6, 2003 Prepared for. AYRES AND ASSOCIATES 3665 JFK PARKWAY BUILDING 2 — SUITE 200 FORT COLLINS, COLORADO 80527 ATTN: CHRIS CARLSON Prepared by. Terracon 301 North Howes Street Fort Collins, Colorado 80521 1rerraco 0 I I rerra on 301 North Howes • P.O. Box 503 Fort Collins, Colorado 80521-0503 (970) 484-0359 Fax: (970) 484-0454 May 6, 2003 Ayres Associates 3665 JFK Parkway Building 2 — Suite 200 Fort Collins, Colorado 80527 Attn: Chris Carlson Re: Geotechnical Engineering Report Proposed Pedestrian Bridge Cache La Poudre River at Overland Trail Road Fort Collins, Colorado Terracon Project No. 20035024 Terracon has completed a geotechnical engineering exploration for the proposed pedestrian bridge to span the Cache La Poudre River near the river's intersection with Overland Trail Road north of Fort Collins, Colorado. This study was performed in general accordance with our Proposal No. D2002280 dated July 25, 2002, and modified to comply with the project specifications at the time of our field exploration. The results of our engineering study, including the boring location diagram, laboratory test results, and the geotechnical engineering recommendations needed to aid in the design and construction of foundations and other earth connected phases of this project are attached. Initially, we proposed to drill 4 test borings. However, due to accessibility issues and alluvial deposits, we were only able to drill 2 borings. The subsoils encountered on the bank of the river, in Test Boring No. 1; consisted of an approximate 6-inch layer of silty topsoil underlain by silty clayey sand extending to the coarse silty sand with gravel and/or silty sand with intermittent cobbles extending to the bedrock below. Claystone/siltstone bedrock was encountered at an approximate depth of 20-feet below existing site grade in Test Boring No. 1. The soils encountered within the river, Test Boring No. 4, consisted of silty sand with gravel and cobbles to the maximum depth explored, where auger refusal Was encountered. Groundwater was encountered at an approximate depth of 8-feet below existing site grades in Test Boring No. 1 and approximately 6-inches below existing site grade in Test Boring No. 4 during initial drilling operations. It is our opinion the proposed bridge structure could be supported by spread footings bearing upon the undisturbed native granular soils extended below the bottom of the river channel Arizona ■ Arkansas ■ California ■ Colorado ■ Georgia ■ Idaho ■ Illinois ■ Iowa ■ Kansas ■ Kentucky ■ Minnesota ■ Missouri Montana,■ Nebraska ■ Nevada ■ New Mexico ■ North Carolina ■ Oklahoma ■ Tennessee ■ Texas ■ Utah ■ Wisconsin ■ Wyoming Consulting Engineers & Scientists Since 1965 www.terracon.com Geotechnical Engineering Exploration Proposed Pedestrian Bridge " Terracon-- Cache La Poudre River @ Overland Trail Road Project No. 20035024 provided hydraulic and scour concerns are dealt with. Other design and construction recommendations, based upon geotechnical conditions, are presented in the report. We appreciate the opportunity to be of service to you on this phase of your project. If you have any questions concerning this report, or if we may be of further service to you, please do not hesitate to contact us. Sincerely, TERRACON �7 Daniel R. Copies lbert, P.E. Engineer Addressee (4) City of Fort Collins — Park Planning (1): Mr. Jason Stutzman Y. Manager x. TABLE OF CONTENTS Letter of Transmittal .......................... Page No. I ...................... i INTRODUCTION................................................................................................................. I PROPOSED CONSTRUCTION..........................................................................................I SITEEXPLORATION..........................................................................................................2 FieldExploration...................................................................................................... 2 Laboratory Testing................................................................................................... 2 SITE CONDITIONS.............................................................................................................3 SoilConditions..................................................................................... Field and Laboratory Test Results........................................................................... 3 Groundwater Conditions..........................................................................................3 ENGINEERING ANALYSES AND RECOMMENDATIONS.................................................4 Geotechnical Considerations................................................. 4 ............................. Foundation Systems...............................................................................................4 LateralEarth Pressures........................................................................................... 5 SeismicC Considerations........................................................................................... 5 Earthwork................................................................................................................ 5 General Considerations................................................................................ 5 SitePreparation........................................................................................... 5 C Fill Materials and Placement .................................. ........................... Excavation and Trench Construction............................................................7 Additional Design and Construction Considerations.................................................7 r Underground Utility Systems ............................................... 7 CorrosionProtection.....................................................................................7 GENERALCOMMENTS.....................................................................................................8 APPENDIX A Site Plan and Boring Location Diagram Logs of Borings APPENDIX B [ General Notes GEOTECHNICAL ENGINEERING REPORT PROPOSED PEDESTRIAN BRIDGE CACHE LA POUDRE RIVER AT OVERLAND TRAIL ROAD FORT COLLINS, COLORADO TERRACON PROJECT NO. 20035024 MAY 6, 2003 INTRODUCTION This report contains the results of our geotechnical engineering exploration for the proposed pedestrian bridge to span the Cache La Poudre River near the river's intersection with Overland Trail Road north of Fort Collins, Colorado. The site is located in the Northeast 1/4 of Section 32, Township 8 North, Range 69 West of the 6th Principal Meridian, Larimeir County, Colorado. The purpose of these services is to provide information and geotechnical engineering recommendations relative to: 1 subsurface soil and bedrock conditions Igroundwater conditions • foundation design and construction Ilateral earth pressures • earthwork Idrainage The recommendations contained in this report are based upon the results of field and laboratory I testing, engineering analyses, and experience with similar soil conditions, structures and our understanding of the proposed project. PROPOSED CONSTRUCTION Based on information provided, we understand the proposed construction will consist of a pre- fabricated metal pedestrian bridge spanning the Cache La Poudre River near the intersection with Overland Trail Road north of Fort Collins, Colorado. It is our understanding the bridge is to be supported by concrete columns extending to spread footings bearing upon the native granular soils below the river channel. Anticipated loads were not provided prior to our site exploration, however, it is assumed the reaction loads at each abutment will be on the order of 50 to 100 kips. 1 Geotechnical Engineering Exploration Proposed Pedestrian Bridge Cache La Poudre River @ Overland Trail Road Project No. 20035024 SITE EXPLORATION Terracon The scope of the services performed for this project included a site reconnaissance by a geotechnical engineer and an engineering geologist, a subsurface exploration program, laboratory testing and engineering analyses. Field Exploration A total of 2 test borings were drilled on April 2 and 16, 2003, to approximate depths of 7 to 30- feet below existing site grades at the locations shown on the Site Plan, Figure I. Test Boring Nos. 2 and 3 were not drilled due to lack of equipment accessibility encountered during the site exploration. The test borings drilled at the site were advanced with a truck -mounted drilling rig, utilizing 4-inch diameter solid stem and/or 3-1/4 inch inside diameter hollow stem auger. The borings were located in the field by pacing from existing site features. The accuracy of boring locations should only be assumed to the level implied by the methods used. Lithologic logs of the borings were recorded by the geotechnical engineer and/or the engineering geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by means of driving split -spoon samplers. i 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 in estimating the consistency, relative density or hardness of the materials encountered. Groundwater conditions were evaluated in each boring at the time of site exploration. 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 of bedrock were classified in accordance with the general notes for Bedrock Classification. At that time, the field descriptions were confirmed or modified as necessary and 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. Laboratory tests were conducted on selected soil samples. The test results 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 other accepted standards. Selected soil and bedrock samples were tested for in -situ moisture contents. Pa