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HomeMy WebLinkAboutHORSETOOTH BUSINESS PARK PUD - Filed GR-GEOTECHNICAL REPORT/SOILS REPORT -4110 REPORT OF A GEOTECIINICAL INVESTIGATION FOR PAVEMENT DESIGN COLLINS BUSINESS PARK ft 7 s-ETo o7r/ . R vs"iEss PORK COLLINS PARK VENTURE DENVER, COLORADO PROJECT NO. 11703-82 BY EMPIRE LAI3ORATORIES, INC. 214 NORTH NOWES STREET FORT COLLINS, COLORADO 80521 TABLE OF CONTENTS Table of Contents i Letter of Transmittal Report 1 Appendix A A-1 Test Boring Location Plan A-2 Key to Borings A-3 Log of Borings A-4 Appendix B E3-1 iivoern Stabilometer Results E3-2 Summary of Test Results 13-3 Appendix C C-1 Inc. Branch Offices Empire La atoriea, In 1242 Bramwood Place MATERIALS AND FOUNDATION ENGINEERS Longmont,Colorado 3I 11P.O. Box 35 214 No. Howes Fort Collins,Colorado 80522 303) 776 3921 P.O.Box 429 (303)484-0359 3151 Nation Way Cheyenne,Wyoming 82001 P.O. Box 10076 March 30, 1982 307) 632-9224 Collins Park Venture 1660 South Albion Street Denver, Colorado 80222 Attention: Mr. Phil Christensen Gentlemen: We are pleased to submit our Report of a Geotechnical investigation prepared for the streets In Collins Business Park located in southeast Fort Collins, Colorado. Based upon our findings In the subsurface, we feel that the site is suitable for the proposed roadway construction, providing the design criteria and recommendations set forth In this report are met. The accompanying report presents our findings in the subsurface and our recou mcI*d3tions based upon these findings, Very truly yours, EMPIRE LABORATO ES, it 1F, logo7 . cl Iiff I' c I R. Sherred k' '".».' '•.*' 09 .d° Senior Engineering Geologist 14c0,, R. stor. % 444"FaBSIJN _ Reviewed by: r F,S .. ,e.• vim . ia n 1 I Chester C. Smith, P.E.li. 1. President cic I r • I (;i)\. • cc JMmts 11. Stewart and Associates, Inc. atb IV M MEMBER OF CONSULTING ENGINEERS COUNCIL r) li REPORT OF A GEOTECHNI CAL INVESTIGATION SCOPE This report presents the results of a geotechnical evaluation prepared for the design of the proposed streets In Collins pusfness Park, located at the southwest corner of Horsetooth and Timberline Roads in southeast Fort Collins, Colorado. The scope of the project included test borings and laboratory testing of samples obtained from these borings. The objectives of this study were to (1) determine the soil and groundwater conditions at the site, (2) determine criteria for pavement design, and (3) make recommendations regarding the proposed street improvements, pavement types, and thicknesses at the site. SITE EXPLORATION The field exploration, carried out on March 16, 1962, consisted of drilling, logging, and sampling five (5) test borings. The locations of the test borings are shown on the Test Boring Location Plan Included In Appendix A of this report. Boring logs prepared from the field logs are shown in. Appendix A. These logs show soils encountered, location of sampling, and groundwater at the time of the exploration. The borings were advanced with a four-Inch diameter, continuous- type, power-flight auger drill. During the drilling operations, a geotechnicai engineer from Empire Laboratories, Inc. was- present and made continuous observations of the soils encountered. 1- a SITE LOCATION AND DESCRIPTION The property Is located at the southwest corner of Itorsetooth and Timberline Roads In southeast Fort Collins, Colorado. More particularly, the site is described as Collins Business Park, First Filing, situate in the northeast 1/4 of Section 31 , Township 7 North, Range 68 West of the Sixth P.M. , Ladner County, Colorado. The site consists of fallow farm land bordered on the north by IL,rsetuoth Road, on the east by Timberline Road, and on the west by the Union Pacific railroad. The property currently Is sparsely vegetated with grass and weeds.. The tract. Is relatively flat and has minor drainage to the east. LABORATORY TESTS AND EVALUATION Samples obtained from the test borings were subjected to testing in the laboratory to provide a sound basis for evaluating the physical properties of the soils encountered. Moisture contents, dry unit weights, and the Atterbery limits were determined. A summary' of the test. results is included In Appendix B. Hveern stabliorne ter tests were run 0 to determine "R" values, and curves showing these data are included i, Appendix B. SOIL Atii GROUNDWATER CONDITIONS The soil profile at the site consists of strata of materials ar - ranged in different combinations. In order of Increasing depths, they are as follows: 1 ) Silt ... Topsoil: A six (6) to twelve (12) inch layer of silty topsoil was encountered in Borings 1 , 3, and 5 at the surface. The upper six (6) inches of the topsoil has been penetrated by root growth and organic matter and should not he used for roadway subdrade or as embankment material. 2- 2) Fill P1e+terlal: A six (6) Inch layer of fill material was • encountered at the surface of Boring 4 and consists of a heterogeneous mixture of silt. sand, and gravel. Six (6) Inches of gravel base and/or subbase material was encountered at the surface of Boring 2. 3) Sandiy_Silty. Clay: This stratum underlies the topsoil and fill and extends to the depths explored. The silty clay is plastic and contains varying amounts of sand. It varies from a brown slightly sandy silty clay to a tan to red sandy silty clay containing traces of gravel. In general, the clay stratum is moderately plastic and is damp to moist In Its natural in situ condition. 4) Groundwater: At the time of the investigation, free groundwater was encountered in Boring 5 at a depth of seven 7) feet below the surface. llo free groundwater was encountered In the remaining test borings to depths eight (8) feet below the surface. Water levels in this area may .be subject to change due to seasonal variations and irrigation demands on and/or adjacent to the •site. RECOMMENDATIONS AND DISCUSSION. It Is our understanding that East Horsetooth Road Is to be widened, Timberline toad Is to be (reproved and reconstructed, and local conenerclal streets will be built within the proposed Collins Business Perk. Based on profiles provided to us by .James II. Stewart and Associates, Inc. , maximum cuts and fills of less than two (2) feet are proposed for all streets within the business park. Both rigid and flexible pavement sections have been evaluated for the proposed streets at the site. The street design is based on the City of Fort Collins "Design Criteria and Standards for Streets," dated September 1961 . Eighteen (18) kip equivalent daily load applications for iorsetuuth and Timberline Roads were provided by James H. Stewart and 3- Associates, Inc. , and eighteen (18) kip equivalent daily load applications fur the local commercial streets were assumed• by Empire Laboratories, inc. The City of Fort Collins "Design Criteria and Standards for Streets," a projected eighteen (18) kip equivalent daily load application of fifty (S0) for East Horsetooth and Timberline Roads and twenty (20) for the local commercial streets, and an "R" value of 15 determined from ilveem stablioreeter tests correlated with a "K" value of one hundred twenty (120) pounds per square inch per inch were utilized for the pavement design. Site_Gradlreer1 It is recommended that the upper six (6) inches of topsoil below proposed streets be stripped and stockpiled for reuse In planted areas. The existing asphalt along Timberline Road should also be removed and wasted off the site. The upper six (6) Inches of the natural subgrade or existing gravel base which may be utilized as. subgrade should be scarified and recompacted at or wet of optimum moisture to at least ninety-five percent (95%) o.f Standard Proctor Density ASTM D 69B-78. See Appendix C.) All till should consist of on-site soils or Imported eiateriai having an II" value of 15 or greater and approved by the geotechnical engineer. The fill should be placed In uniform six (6) to eight (8) inch lifts and compacted at or wet of optimum moisture to at least ninety-five percent 95%) of Standard Proctor Density ASTM D 698-78. Finished subgrade In cut sections should be scarified a minimum of six (6) inches and recompacted at or wet of optimum moisture to at least ninety-five percent 95%) of Standard Proctor Density ASTM D 698-78. Cut and fill slopes should be pieced on grades no steeper than 2:1 . Each successive lift of fill placed on embankment slopes should be benched slightly into the existing grade. All street subgrade should be i)leeed a minimum of three (3) feet abovu existing groundwater elevations. It Is recommended that all stripping, subgrade preparation, and fill placement be inspected by the geotechnical engineer. Field density tests should be taken. in the compacted subgrade and fill under 6- the supervision of the gcotechnical engineer to ensure proper compaction. Flexible Pavement It Is our opinion that flexible pavement Is a suittable alternate for roadway construction at the site. The flexible pavement alternate at. the site should consist of asphaltic concrete underlain by crushed aggregate. base course Or asphaltic concrete underlain by plant mix bituminous base cour ie. Using the City of Fort Collins "Design Criteria and Standards for Streets," a serviceability index of 2.5, u regional factor of 0.75, an "R" value, of 15, a twenty (20) year design life, an eighteen 18) kip equivalent daily load application of fifty (50) for ilorsetooth and Timberline Roads and twenty (20) for local commercial streets, and weighted structural numbers of 2.85 for Ilorsetoot.h and Timberline Roads and 2.50 for local commercial streets, the following pavement thicknesses are recommended: Iior-5ctooth and Timberline goads Asphaltic Concrete 9" Crushed Aggregate Base Course 9" Total Pavement Thickness 13" Asphaltic Concrete 3" tiI Bituminous Base Course 4}" Total Pay.cent Thickness 7;'+ Local Commercial Streets Asphaltic Concrete 3" Crushed Aggregate Base Course 10" Total Pavement Thickness 13" 5- Asphaltic. Concrete 2" Plant Mix Bituminous Base Course . 31" Total Pavement Thickness 5}= The crushed aggregate base course should meet City of Fort Collins Class 6 apecificationa. The subgrade below the proposed asphalt paverient should be prepared in accordance with the recommendations dh.r`ussed in the "Site Grading" section of this report. Upon proper preparation of the subgrado, the base course should be placed and compacted at optimum moisture to at least ninety-eight percent (98%) of Standard Proctor Density ASTP-t i) 698-78. (See Appendix C.) It is recommended that the asphaltic concrete and/or plant mix bituminous base be placed in two (2) to three (3) Inch lifts. Ali plant mix lrt:;e course and asphaltic concrete should meet City of Fort Collins specifications and should be placed In accordance with those specifications. All base course material should have a minimum "R" value of 78, the piarst Alai( bituminous base should have an Rt value of 90 or greater anti the asphaltic concrete should have an F'.t value of 95 or greater. Field density tests should be taken in the aggregate base, bituminous base, and asphalt under the direction of the geotechnlcal engineer. itigid Pavement A feasible foundation alternate at the site would be rigid pavement. Using the eighteen (18) kip equivalent daily load applications described above, a modulus of subgrade reaction of one hundred twenty (120) pounds per squire inch per inch based on an "R" value of 15, a design life of twc.rnty (20) years, and a concrete design with a modulus of. rupture of five hundred fifty (550) pounds per square inch, the following pavement thicknesses are recommended: Iiorsetooth and Timberline Roads F cnrelnforced Concrete - 51" 6- l.c>cal Commercial Streets NonreIr forced Concrete - 41" it is recommended that ell existing asphalt along Timberline Road be removed. The suhgrade below propcsod roadways should be prepared In ae:cerdencc with the recommendations discussed in the "Site Grading" section of this report. The concrete pavement should be placed directly on the subgrada that has been uniformly and properly prepared in accordance with the above recommendations. All concrete used In the pavement shall meet ASTi.t specifications, and all aggregate shall conform to ASTM C-33 specifications. The concrete should be designed with a minimum modulus of rupture of five hundred fifty (550) pounds per squire inch In twenty-eight (28) days. It Is recommended that laboratory mix designs be done to determine the proper proportions of aggregate, cement, and water necessary to meet the requirements. It is essential that the concrete have a low water-cement ratio, an adequate cement factor, and sufficient quantities of entrained air. Joints should be carefully designed and constructed In accordance with the City of Fort Collins "Design Criteria and Standards for Streets" to insure good performance of the pavement. It is recommended that all concrete pavement be placed in accordance with City of Fort Collins specifications. If paving is done during cold weather, acceptable cold weather procedures as outlined in the City specifications should he utilized. The concrete pavement should be properly cured and protected in accordance with the above specificetions. Concrete injured by frost should be removed and replaced. It is recommended that the pavement not be opened to traffic until a flexible strength of five hundred fifty (550) pounds per square inch is obtained er .i rni irnunt of fourteen (14) days after the concrete hes been pieced GENERAL COMMENTS This report hue been prepared to old In the evaluation of the prole-rty end to neeist the engineer In the design of this project. In 7- the event that any changes in the design of the pavement structure are planned, the conclusions and recommendations contained In this report will not be considered valid unless said changes are reviewed and conclusions of this report modified or approved in writing by Empire i_ahorctorie;s, Inc. , the gentcchnical engineer of record. Every effort was made to provide comprehensive site coverage through careful locations of the test borings, while keeping the site investigation economically feasible. Variations In soil and groundwater conditions between test borings may he encountered during construction. In order to permit correlation between the reported subsurface conditions nd the actual conditions encountered during construction and to aid in carrying out the plans and specifications as originally contemplated, it is recommended that Erirlre Laboratories, Inc. be retained to perform ccnntiiesoun construction review during the excavation and foundation phescs of the work. Empire Laboratories, Inc. assumes no responsibility for compliance with the recommendations included in this report unless they have been retained to perform adequate on-site construction review during the course of construction. 8- APPENDIX A. TEST BORING LOCATION PLAN GoLLi t\ s bJls i rAr Ite12-5 -rexf r.,0A > 31 .7, 68 t-c. I2 3 2 1 Q . f 3 0 ul r 3o0I A-2 i t n ir- 4 KEY TO BORING LOGS I i TOPSOIL GRAVEL de, FILL SAND& GRAVEL Owilhoo e SILT e i•/ SILTY SAND& GRAVEL r—,1 CLAYEY SILT sp COBBLES i •SANDY SILT a• SAND,GRAVEL& COBBLESi. ,. CLAY WEATHERED BEDROCK ElSILTY CLAY SILTSTONE BEDROCK SANDY CLAY NEN CLAYSTONE BEDROCK SAND SANDSTONE BEDROCK SILTY SAND s LIMESTONE CLAYEY SAND 17111311 GRANITE SANDY SILTY CLAY SHELBY TUBE SAMPLE nSTANDARD PENETRATION DRIVE SAMPLER WATER TABLE 7 Days AFTER DRILLING C HOLE CAVED 5/12 Indicates that 5 blows of a 140 pound hammer falling 30 inches was required to penetrate 12 inches. A-3 a LOG OF BORINGS t7i N_ 2 N 3_ 0 7. • 8/12 9/12 NC. 16/12 ,/ 5 10/12 •l 11/12 •/ 10/12 1 10 15 A-4 EMPIRE LABORATORIES, INC. LOG OF BORINGS 1.1Q 0 9/12 (/. 5/12 5 4/12 10 EMPIRE I.ABORATdRIES, INC. APPENDIX B. 111 1 I- _I -1 _ I:_, ( 1 E I - ' j_ R E l_1 [_ 1 `._, 1:1 I F1 L. 1.-IL I.IH5 VEI•ITUF E II'I•,:, I II..1 4 I'!'_; }:.1_1'_.T NE-L.' 7. ('r't='1 1 I_ + . +"+ • I.' 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O r N N-r N I\e- N N r N r N 01 • OZ r N Cr) d' LO CO R_Z CV e.)O O n Cr) U) CO r J ... 11) r- to r-- gzrct r U lD Cr) CV r CO r- cr) L11 CO Cr) I17 CO cr r- - r- IC)• M I U tD Cr) CV r to 1 CV Cr) CO n r tO CV r 1 J v C) O In O It) Cr, N U tD Cr) CV r- CO r 1 r- V) CD a w CO cc O O tO tD d Cr) Lad J v C\I r L1) Cr) r r Cr) U tO CY) C\! r I O cM CO CO O n d tD J -+• r O n 01 03 CV 1D C..) tD Ch r r- L1) 1 r 0 CZ I-- Z O O LJ F— ti r O 1--4 m -I E N X F- O I . >-- W Q O 2 --• J F- CD 0 U F= L U C U •-• •-' U 0 2 CD LU 0 •-• •--• Cl) Lii D •--• F- F- N O V) •- It) V) V). Cr V) L.L_ O• O' J J O CL J Q CO J 0- fZ CD U 0 Q APPENDIX C. APPENDIX C. Suggested Specifications for Placement of Compacted Earth Fill and/or Backfills. GENERAL A soils engineer shall be on-site to provide continuous observation during filling and grading operations and shall be the owner's repre- sentative to inspect placement of all compacted fill and/or backfill on the project. The soils engineer shall approve all earth materials prior to their use, the methods of placing, and the degree of compaction obtained. MATERIALS Soils used for all compacted fill and backfill shall be approved by the soils engineer prior to their use. The upper two (2) feet of compacted earth backfill placed adjacent to exterior foundation walls shall be an impervious, nonexpansive material . No material , including rock, having a maximum dimension greater than six inches shall be placed in any fill . Any fill containing rock should be carefully mixed to avoid nesting and creation of voids. In no case shall frozen material be used as a fill and/or backfill material. PREPARATION OF SUBGRADE All topsoil , vegetation (including trees and brush), timber, debris, rubbish, and other unsuitable material shall be removed to a depth satisfactory to the soils engineer and disposed of by suitable means before beginning preparation of the subgrade. The subgrade surface of the area to be filled shall be scarified a minimum depth of six inches, moistened a.s necessary, and compacted in a manner specified below for the subsequent layers of fill . Fill shall not be placed on frozen or muddy ground. PLACING FILL No sod, brush, frozen or thawing material , or other unsuitable material shall be placed in the fill , and no fill shall be placed during unfavorable weather conditions. All clods shall be broken into small pieces, and distribution of material in the fill shall be such as to preclude the formation of lenses of material differing from the surrounding material. The materials shall be delivered to and spread on the fill surface in a manner which will result in a uniformly compacted fill . Each layer shall be thoroughly blade mixed during spreading to insure uniformity of material and moisture in each layer. Prior to compacting, each layer shall have a maximum thickness of eight inches, and its upper surface shall be approximately horizontal . Each successive 6" to 8" lift of fill being placed on slopes or hillsides should be benched into the existing slopes, providing good bond between the fill and existing ground. MOISTURE CONTROL While being compacted, the fill material in each layer shall as nearly as practical contain the amount of moisture required for optimum compaction or as specified, and the moisture shall be uniform throughout the fill . The contractor may be required to add necessary moisture to the fill material and to uniformly mix the water with the fill material if, in the opinion of the soils engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. If, in the opinion of the soils engineer, the material proposed for use in the compacted fill is too wet to permit adequate compaction, it shall be dried in an acceptable manner prior to placement and compaction. COMPACTION When an acceptable, uniform moisture content is obtained, each layer shall be compacted by a method acceptable to the soils engineer and as specified in the foregoing report as determined by applicable standards. Compaction shall be performed by rolling with approved tamping rollers, r_ pneumatic-tired rollers, three-wheel power rollers, vibratory compactors, or other approved equipment well-suited to the soil being compacted. If a sheepfoot roller is used, it shall be provided with cleaner bars attached in a manner which will prevent the accumulation of material between the tamper feet. The' rollers should be designed so that effective weight can be increased. MOISTURE-DENSITY DETERMINATION Samples of representative fill materials to be placed shall be furnished by the contractor to the soils engineer for determination of maximum density and optimum moisture or percent of Relative Density for these materials. Tests for this determination will be made using methods conforming to requirements of ASTM D 698, ASTM D 1557, or ASTM D 2049. Copies of the results of these tests will be furnished to the owner, the project engineer, and the contractor. These test results shall be the basis of control for all compaction effort. DENSITY TESTS The density and moisture content of each layer of compacted fill will be determined by the soils engineer in accordance with ASTM D 1556, ASTM D 2167, or ASTM D 2922. Any material found not to comply with the minimum specified density shall be recompacted until the required density is obtained. Sufficient density tests shall be made and submitted to support the soils engineer's recommendations. The results of density tests will also be furnished to the owner, the project engineer, and the contractor by the soils engineer.