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HomeMy WebLinkAboutJFK PARKWAY - Filed GR-GEOTECHNICAL REPORT/SOILS REPORT -REPORT OF A GEOTECHNICAL INVESTIGATION FOR PROPOSED BOX CULVERT JFK PARKWAY OVER LARIMER NO. 2 CANAL PARSONS AND ASSOCIATES FORT COLLINS, COLORADO PROJECT NO. 9539-92 f:3M EMPIRE LABORATORIES, INC. 301 NORTH HOWES STREET FORT COLLINS, COLORADO 80521 TABLE OF CONTENTS Table of Contents .............................................. i Letter of Transmittal .......................................... ii Report......................................................... 1 Appendix A.......................................0.9.0........ A -1 Test Boring Location Plan .................................... A-2 Key to Borings ............................................... A -3 Log of Borings ............................................... A-4 Appendix B.................................................... B -1 Summary of Test Results ..................................... B-2 Appendix C ..... . . . .... .. . • . • . . . .. . . . . . . .. • .. • . . . ..... .. . • ..... C - 1 Empire Laboratories, Inc. GEOTECHNICAL ENGINEERING 8 MATERIALS TESTING October 5, 1992 Parsons 8 Associates 432 Link Lane Plaza Fort Collins, Colorado 80524 Attention: Mr. Jeff Couch Gentlemen: CORPORATE OFFICE P.O. Box 503 • 301 No. Howes Fort Collins, Colorado 80522 303) 484-0359 FAX No. (303) 484-0454 We are pleased to submit our Report of a Geotechnical Investigation prepared for the proposed box culvert carrying JFK Parkway across the Larimer No. 2 Canal in south Fort Collins, Colorado. Based upon our findings in the subsurface, it is our opinion the site is suitable for the proposed 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 recommendations based upon these findings. Very truly yours, EMPIRE LABORATORIES INC. Zlil&Verrod Senior Engineering Geologist Reviewed by: Chester C. Smith, P.E. Division Manager cic Branch Offices P.O. Box 16859 P.O. Box 1135 P.O. Box 1744 P.O. Box 5659 Colorado Springs, CO 80935 Longmont, CO 80502 Greeley, CO 80632 Cheyenne, WY 82003 719) 597-2116 (303) 776-3921 (303) 351-0460 (307) 632-9224 Member of Consulting Engineers Council REPORT OF A GEOTECHNICAL INVESTIGATION SCOPE This report presents the results of a geotechnical investigation prepared for the proposed box culvert located across the Larimer No. 2 Canal on JFK Parkway just north of Bockman Drive in south Fort Collins, Colorado. The investigation included test borings and laboratory testing of samples obtained from these borings. The objectives of this study were to (1) evaluate the subsurface conditions at the site relative to the proposed construction, (2) make recommendations regarding the design of the substructure, and (3) recommend certain precautions which should be taken because of adverse soil and/or ground water conditions. SITE EXPLORATION The field exploration, carried out on September 30, 1992, consisted of drilling, logging, and sampling two (2) test borings. The test borings were located by Empire Laboratories, Inc. from the existing canal and Bockman Drive using conventional chaining methods. 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 ground water 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 geotechnical engineer from Empire Laboratories, Inc. was present and made continuous observations of the soils encountered. 1- SITE LOCATION AND DESCRIPTION The site is located north of Bockman Drive at the Larimer No. 2 Canal in south Fort Collins, Colorado. More particularly, the site is described as a tract of land situate in the Northwest 1 /4 of Section 36, Township 7 North, Range 69 West of the Sixth P.M., Larimer County, Colorado. The site consists of a vacant tract of land currently vegetated with native grass and weeds. Trees line the banks of the Larimer No. 2 Canal. The canal is approximately eight -foot deep and ten -foot wide through the project area. The area is relatively flat and has minor drainage to the southeast. The Toys "R" Us building is located to the west, and residential housing is located to the east. The area to the south is vacant. The north side of the Canal is a vacant tract of relatively flat land. This area is vegetated with grass and weeds. LABORATORY TESTS 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, water soluble sulfates, swelling potentials, and the Atterberg limits were determined. A summary of the test results is included in Appendix B. SOIL AND GROUND WATER CONDITIONS The soil profile at the site consists of strata of materials arranged in different combinations. In order of increasing depths, they are as follows: 1) Silty Topsoil: The area tested is overlain by a six (6) inch layer of silty topsoil. The topsoil has been penetrated by root growth and organic matter and should not be used as a bearing soil or as a fill and/or backfill material. 2- 2) Sandy Silty Clay: This stratum underlies the topsoil and extends to the bedrock below. The silty clay is plastic, contains a large percentage of fine to medium grained sand, is dry to damp and exhibits generally moderate bearing characteristics. 3) Sandstone-Siltstone Bedrock: The bedrock was encountered below the upper clays at depths of three and one-half (3-1/2) to four and one-half (4-1 /2) feet below the surface and extends to greater depths. The upper one (1) to one and one-half 1-1 /2) feet of the sandstone interbedded with minor amounts of siltstone is highly weathered; however, the underlying bedrock is firm to dense and exhibits very high bearing characteristics. When wetted, the siltstone portion of the bedrock exhibits slight swell potential. 4) Ground Water: At the time of the investigation, no free ground water was encountered at the site to the depths explored. Water levels in this area are subject to change due to seasonal variations, irrigation demands on and/or adjacent to the site and the volume of flow in the Larimer No. 2 Canal through the project area. In addition, it is our opinion surface water may percolate through the upper subsoils and become trapped on the relatively impervious bedrock forming a perched ground water condition. RECOMMENDATIONS AND DISCUSSION It is our understanding a three -sided, reinforced concrete box culvert is to be constructed to carry JFK Parkway across the Larimer No. 2 Canal. The foundation for the box culvert will be placed approximately three (3) feet below the bottom of the canal. The culvert will have a twenty -foot span and will have eight -inch thick concrete wal Is. 3- r:­_A n+:-- In view of the loads transmitted by the proposed box culvert and the soil conditions encountered at the site, it is recommended the structure and wing walls be supported by conventional -type spread footings and/or continuous grade beams. Footings and/or grade beams should be founded on the original, undisturbed bedrock stratum a minimum of thirty (30) inches below finished grade for frost protection. The identification and undisturbed nature of the bedrock should be verified by the geotechnical engineer prior to placement of foundation concrete. Footings and/or grade beams founded at the above level may be designed for a maximum allowable bearing capacity of four thousand 4000) pounds per square foot (dead load plus maximum live load). To counteract swelling pressures which may develop if the bedrock becomes wetted, footings and/or grade beams should be designed for a minimum dead load of five hundred (500) pounds per square foot. Resistance to sliding may be evaluated using a coefficient of friction of the concrete to the bedrock stratum of .50. The predicted settlement under the above maximum loading should be negligible. It is recommended construction be done when the canal is dry. If this is not possible, all footing excavations should be thoroughly dewatered prior to excavation, placement of foundation concrete and/or backfill. Backfi Il Backfill placed adjacent to the box culvert and wing walls should consist of the on -site sandy silty clay soils or excavated bedrock broken into pieces of three (3) inches or less or imported granular material approved by the geotechnical engineer. The backfill should be mechanically compacted between optimum moisture and two percent (20) wet of optimum moisture in uniform six (6) to eight (8) inch Lifts to a minimum of ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78 (see Appendix C) or eighty percent (80%) of Relative Density ASTM D 4253, D 4254. Puddling of backfill should not be permitted as a method of compaction. Culvert and wing walls backfilled with the on -site 4- sandy silty clay soils or bedrock should be designed using a hydrostatic pressure distribution and equivalent fluid pressure of fifty (50) pounds per cubic foot per foot depth of backfill. In addition, all hydrostatic forces acting on the wall should be taken into account in the design of the structure. GENERAL RECOMMENDATIONS 1) Laboratory test results indicate water soluble sulfates in the soil are negligible, and a Type 1-II cement may be used in concrete exposed to subsoils. Slabs on grade subjected to de-icing chemicals should be composed of a more durable concrete with low water -cement ratios and higher air contents. 2) Finished grade should be sloped away from the structure on all sides to give positive drainage. Five percent (5%) for the first ten (10) feet away from the structure is the suggested slope. 3) Footing and/or grade beam sizes should be proportioned to equalize the unit loads applied to the soil and thus minimize differential settlements. 4) It is recommended compaction requirements in the project specifications be verified in the field with density tests performed under the direction of the geotechnical engineer. 5) It is recommended a registered professional structural engineer design the substructure, and he should take into account the findings and recommendations of this report. GENERAL COMMENTS This report has been prepared to aid in the evaluation of the property and to assist the architect and/or engineer in the design of this project. In the event any changes in the design of the structure 5- or its location 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 Laboratories, Inc., the geotechnical 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 viable. Variations in soil and ground water conditions between test borings may be encountered during construction. In order to permit correlation between the reported subsurface conditions and the actual conditions encountered during construction and to aid in carrying out the plans and specifications as originally contemplated, it is recommended Empire Laboratories, Inc. be retained to perform continuous construction review during the excavation and foundation phases 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. APPENDIX A TEST BORING LOCATION PLAN o P7K --,Lj LA#21r1 R LA A-2 EMPIRE LABORATORIES. INC. KEY TO BORING LOGS 7,01 TOPSOIL L•; GRAVEL FILL V' V*I SAND & GRAVEL SILT o SILTY SAND & GRAVEL F-71 CLAYEY SILT M-771 op COBBLES SANDY SILT c SAND, GRAVEL & COBBLES CLAY WEATHERED BEDROCK i SILTY CLAY SILTSTONE BEDROCK SANDY CLAY CLAYSTONE BEDROCK SAND rI SANDSTONE BEDROCK 0 i. . SILTY SANG LIMESTONE CLAYEY SAND R` x x 1[Rx GRANITE SANDY SILTY CLAY a SHELBY TUBE SAMPLE STANDARD PENETRATION DRIVE SAMPLER WATER TABLE 0 hrS AFTER DRILLING C HOLE CAVED T 5/12 Indicates that 5 blows of a 140 pound hammer failing 30 inches was requires A-3 EMPIRE LABORATORIES, INC. 4930 4925 4920 4915 4910 LOG OF BOWNGS 0. I a- z Q- m wommm m Nam A-4 EMPIRE LABORATORIES, INC. APPENDIX B C N r-1 N e 1 00 M N I 00 L0 N t\ n O O N O O OdmMLOLnr-1 LO LO LO r s O U o O Ln GN7 N _ Q r1 U L0 I Q C m O O 9 U.C. r-I Vm W C d c.E ae co cn J J N H J D N LI a F.. W LL O m1-4 w N O N CQ 7 N O .- 1 n N .I d d Ln a a pp$: ii UN LL Ol C+ 0 Cd Ln O N N y t0 00 th M N I" M r- LO G N LL) O O rl M O I.- LnIf! N r^ 1 to l0 O ri 4 ri 1 LO Ln O e--l. ct I m 1 p- 1 m I. O 1 O 1 O I O I m I O i O 1 O I O S- O ch Ln O d' O CI O l7 N 4 O O -- C} Caz m APPENDIX C APPENDIX C. Suggested Minimum Specifications for Placement of Compacted Earth Fill and/or Backfills GENERAL The geotechnical engineer shall be the owner's, architect's, engineer's or contractor's representative to observe placement. of compacted fill and/or backfill on the project. The geotechnical engineer or his representative shall approve all earth materials prior to their use, the method of placement and the degree of compaction. MATERIALS Soils used for all compacted fill and backfill shall be approved by the geotechnical engineer or his representative prior to their use. Fill material shall be free from organic matter, frozen material and other unsuitable substance and shall not contain rocks or lumps having a diameter greater than six (6) inches. SUBGRADE PREPARATION All topsoil, vegetation, trees, brush, timber, debris, rubbish and all other unsuitable material shall be removed to a depth satisfactory to the geotechnical engineer or his representative. The material shall be disposed of by suitable means prior to beginning preparation of the subgrade. The subgrade shall be scarified a minimum depth of six (6) inches, moisture conditioned as necessary and compacted in a suitable manner prior to placement of fill material. Fill shall not be placed until approval by the geotechnical engineer or his representative; and in no case, shall fill material be placed on frozen or unstable ground. Subgrade which is not stable may require the use of imported granular material, geotextiles or other methods for stabilization as approved by the geotechnical engineer. FILL PLACEMENT Fill material shall not be placed during unfavorable weather conditions. Material proposed for use as fill shall be approved by the geotechnical engineer or his representative prior to use. Proposed import material shall. be approved by the geotechnical engineer or his representative prior to hauling to the project site. Fill material shall be C=2 uniformly mixed such as to preclude the formation of lenses of material differing from the surrounding material. All clods shall be broken into small pieces. The contractor shall construct the fill in approximately horizontal lifts extending the entire length of the fill. The thickness of the layers before compaction shall not be greater than eight (8) inches. Fill being placed on slopes or hillsides shall be benched into the existing slope. A minimum two (2) foot horizontal bench shall be cut into the existing excavated slope for each four (4) feet vertical of fill, or each lift should be benched slightly into the existing grade. MOISTURE CONTROL Prior to and during compaction operations, the fill material being placed shall be maintained within the range of optimum moisture specified. A general recommendation is to maintain the fill material within two percent (2%) plus or minus of optimum moisture so. that proper compaction to the specified density may be obtained with a minimal effort. In building pad and paved areas, material exhibiting swelling potential, shall be maintained between optimum moisture and two percent (2%) wet of optimum moisture content. The moisture content of the fill material shall be maintained uniform throughout the fill. The contractor may be required to add necessary moisture to the fill material and tv uniformly mix the water with the fill material if, in the opinion of the geotechnical engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. If, in the opinion of the geotechnical 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. Uniform mixing may require discing, blading or other methods approved by the geotechnical engineer or his representative. Adjustments of moisture content shall be made on the basis of determinations of moisture content by field tests as construction progresses. COMPACTION The contractor shall furnish and operate the necessary types and kinds of equipment to perform the operations required to obtain the specified compaction. This equipment may include approved tamping rollers, rubber tired rollers, smooth wheeled rollers and vibratory rollers. If a sheepsfoot roller is used, it shall be provided with cleaner bars so attached as to prevent the accumulation of material between the tamper feet. Fill areas which are not accessible to full-sized construction equipment shall be placed in maximum four (4) inch lifts and compacted with power tampers to the specified density. C-3 Compaction should meet the minimum percentages of maximum density as set forth in the project specifications or the recommendations of the report. The contract specifications supercede the recommendations given in this report. MOISTURE DENSITY RELATIONSHIP DETERMINATION Samples of representative fill materials to be placed shall be furnished by the contractor to the geotechnical engineer for determination of maximum density and optimum moisture or relative density. Sufficient laboratory moisture density or relative density curves will be made to determine the optimum moisture content and maximum density for the various soils placed as fill. Tests for this determination will be made using the appropriate method conforming to the requirements of ASTM D 698 (Standard Proctor) , ASTM D 1557 (Modified Proctor.) or ASTM D 4253, D 42.54 (Relative Density). The materials used for fill shall be classified in accordance with ASTM D 2487 in order to permit correlation between the moisture density relationship data and the material being placed and compacted. Copies of the results of these tests will be furnished to the client and others as directed by the client. These test results shall be the basis of control for all compaction effort. FIELD DENSITY AND MOISTURE TESTS The in -place density and moisture content of compacted fill will be determined by the geotechnical engineer or his representative in accordance with ASTM D 1556 (sand cone method) or ASTM D 2922, D 3017 (nuclear methods). Material not meeting the required compaction and/or moisture specifications shall be recompacted and/or moisture conditioned until the required percent compaction and/or moisture content is obtained. Sufficient compaction tests shall be made and submitted to support the geotechnical engineer's or his representative's recommendations. The results of density tests will also be furnished to the client and others as directed. C-4 ADDENDUM TO REPORT OF A GEOTECHNICAL INVESTIGATION FOR \ PROPOSED BOX CULVERT JFK PARKWAY OVER LARIMER NO. 2 CANAL PARSONS & ASSOCIATES FORT COLLINS, COLORADO PROJECT NO. 9539-92 m EMPIRE LABORATORIES, INC. 301 NORTH HOWES STREET FORT COLLINS, COLORADO 80521 TABLE OF CONTENTS Table of Contents .............................................. i Letter of Transmittal.......................0......0..........0 ii Report......................................................... 1 Appendix A .. . ...... ... . • ............... . .. . . ... . ... • 0 ...... 0 • . A - 1 Test Boring Location Plan .................................... A -2 Key to Borings ............................................... A-3 Log of Borings ............................................... A -4 Appendix B......................................... 0.......... B -1 Hveem Stabilometer Data ...................................... B-2 Summary of Test Results ..................................... B-3 Appendix C.................................................... C-1 Empire Laboratories, Inc. GEOTECHNICAL ENGINEERING & MATERIALS TESTING October 19, 1992 Parsons 8 Associates 432 Link Lane Plaza Fort Collins, Colorado 80524 Attention: Mr. Jeff Couch Gentlemen: CORPORATE OFFICE P.O. Box 503 a 301 No. Howes Fort Collins, Colorado 80522 303) 484-0359 FAX No. (303) 484-0454 We are pleased to submit an addendum to our Report of a Geotechnical Investigation prepared for the proposed box culvert across the Larimer No. 2 Canal for proposed JFK Parkway in southeast Fort Collins, Colorado. The purpose of the addendum is to provide recommendations for the design of the pavement of JFK Parkway in the project area. The accompanying addendum presents our findings in the subsurface and our recommendations for pavement design based upon these findings. Very truly yours, EMPIRE LABORATORIES INC. a•:; rdNS 4._ Senior Engineering Geologist Reviewed by: J e`eeeits€rEaertg® Q GISTFq Chester C. Smith, P.E. Division Manager 0 cic Branch Offices P.O. Box 16859 P.O. Box 1135 P.O. Box 1744 P.O. Box 5659 Colorado Springs, CO 80935 Longmont, CO 80502 Greeley, CO 80632 Cheyenne, WY 82003 719) 597-2116 (303) 776-3921 (303) 351-0460 (307) 632-9224 Member of Consulting Engineers Council ADDENDUM TO REPORT OF A GEOTECHNICAL INVESTIGATION SCOPE This addendum presents the results of a geotechnical investigation prepared for JFK Parkway between Bockman Drive and Larimer No. 2 Canal in southeast Fort Collins, Colorado. The investigation included test borings and laboratory testing of samples obtained from these borings. The objectives of this study were to (1) determine the soil and ground water conditions at the site, (2) develop criteria for determining pavement design, and (3) make recommendations regarding pavement types and thicknesses for the proposed JFK Parkway construction at the site. SITE EXPLORATION The field exploration, carried out on October 6, 1992, consisted of drilling, logging, and sampling two (2) additional test borings. Two borings were drilled by Empire Laboratories, Inc. for the proposed box culvert on September 30, 1992. The test borings were located by Empire Laboratories, Inc. from existing property corners using conventional chaining methods. 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 ground water at the time of the exploration. The borings were advanced with four- and six-inch diameter, continuous -type, power -flight auger drill. During the drilling operation, a geotechnical engineer an engineering geologist from Empire Laboratories, Inc. was present and made continuous observations of the soils encountered. 1- SITE LOCATION AND DESCRIPTION The site consists of the proposed J FK Parkway from Bockman Drive to the north side of the Larimer No. 2 Canal. More particularly, the site is described as a tract of land situate in the Northwest 1 /4 of Section 36, Township 7 North, Range 69 West of the Sixth P.M., Larimer County, Colorado. The site consists of a vacant tract of land located between Bockman Drive and Larimer No. 2 Canal. The area is vegetated with native grass and weeds. Trees line the bank of the canal. The area is relatively flat and has minor drainage to the southeast. Toys "R" Us is located to the west, and residential housing is located to the east. The area to the south is vacant. A vacant area vegetated with grass and weeds is located to the north of the canal. 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 Atterberg limits were determined. A summary of the test results is included in Appendix B. A Hveem stabilometer test was run to determine the "R" value of representative subgrade material at the site, and a curve showing this data is included in Appendix B. SOIL AND GROUND WATER CONDITIONS The soil profile at the site consists of strata of materials arranged in different combinations. In order of increasing depths, they are as fol lows 1) Silty Topsoil: The area tested is overlain by a six (6) inch layer of silty topsoil. The topsoil has been penetrated by root growth and organic matter and should not be used as a bearing soi 1. 2- 2) Sandy Silty Clay: This stratum underlies the topsoil in Boring 3 and extends to a depth of five (5) feet below the surface. The silty clay is plastic, contains varying amounts of sand, and is damp to moist in situ. 3) Sandstone-Siltstone Bedrock: This stratum underlies the clay in Boring 1 and the topsoil in Boring 2 and extends beyond the depths explored. The upper one (1) to two and one-half 2-1/2) feet of the bedrock is highly weathered; however, the underlying interbedded siltstone and sandstone is firm. 4) Ground Water: At the time of the investigation, no free ground water was encountered at the site to the depths explored. Water levels in this area are subject to change due to seasonal variations. In addition, it is our opinion surface water may percolate through the subsoils and become trapped on the relatively impervious bedrock, forming a perched ground water condition. RECOMMENDATIONS AND DISCUSSION It is our understanding that JFK Parkway is to be extended from Bockman Drive across the Larimer No. 2 Canal. JFK Parkway has been classified as an arterial street by the City of Fort Collins. Plans indicate that fill will be required for construction of the street. The fill is to come from the proposed detention pond located east of the intersection of JFK Parkway and Bockman Drive in the area of Boring 4. Site Grading, Excavation and Utilities It is recommended the upper six (6) inches of topsoil encountered at the site be stripped and stockpiled for reuse in planted areas. The upper six (6) inches of the natural subgrade below streets should be scarified and recompacted between optimum moisture and two percent 2%) wet of optimum moisture to at least ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78. (See Appendix C.) 1XIM All fill should consist of the on -site soils or imported material having an "R" value of 5 or greater, and this material should be approved by the geotechnical engineer. Any fill placed at the site should be placed in uniform six (6) to eight (8) inch lifts and compacted between optimum moisture and two percent (2°s) wet of optimum moisture to at least ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78. Finished subgrade below all pavement should be placed a minimum of three (3) feet above the bedrock stratum. In areas where subgrade compaction cannot be met due to saturated or unstable conditions, the subgrade should be stabilized by use of granular pit run, geotextiles, lime, fly ash or other suitable means. All excavations should be dug on safe and stable slopes. The slope of the sides of the excavations should comply with local codes or OSHA regulations. Where this is not practical, sheeting, shoring and/or bracing of the excavation will be required. The sheeting, shoring and bracing of the excavation should be done to prevent sliding or caving of the excavation walls and to protect construction workers and adjacent structures. The side slopes of the excavation or sheeting, shoring or bracing should be maintained under safe conditions until completion of backfilling. In addition, heavy construction equipment should be kept a safe distance from the edge of the excavation. Utility trenches dug four (4) feet or more into the upper soils should be excavated on safe and stable slopes in accordance with OSHA regulations, or the excavations should be properly shored. The bedrock may be excavated on vertical slopes. Excavation of the bedrock may require the use of heavy-duty construction equipment equivalent to a truck mounted excavator having a gross weight of ninety thousand 90,000) pounds. Where utilities are excavated below ground water, dewatering will be needed during placement of pipe and backfilling for proper construction. All piping should be adequately bedded for proper load distribution. Backfill placed in utility trenches in open and planted areas should be compacted in uniform lifts between optimum moisture and two percent 2%) wet of optimum moisture to at least ninety percent (90%) of Standard Proctor Density ASTM D 698-78 the full depth of the trench. Backfill placed in utility trenches under roadways and paved areas should be Z2 compacted between optimum moisture and two percent (2s) wet of optimum moisture to at least ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78. Addition of moisture to and/or drying of the subsoils may be needed for proper compaction. Proper placement of the bedrock as backfill may be difficult, as is discussed above. Cuts and fills for the proposed detention ponds should be placed on slopes no steeper than 3:1. Cut areas in the detention ponds should be scarified a minimum of eight (8) inches and compacted plus or minus two percent (2%) of optimum moisture to at least ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78. To minimize erosion, the slopes and bottoms of the detention ponds should be seeded. Pipes or apertures through the detention basins should be surrounded by a minimum of two (2) feet of the on -site or imported clay soil compacted to ninety-eight percent (98%) of Standard Proctor Density ASTM D 698-78. Stripping, grubbing, subgrade preparation, and fill and backfill placement should be accomplished under continuous observation of the geotechnical engineer. Field density tests should be taken daily in the compacted subgrade, fill, and backfill under the direction of the geotechnical engineer. Flexible Pavement It is our opinion flexible pavement is suitable for the proposed street construction at the site. A flexible pavement alternate should consist of asphalt concrete underlain by crushed aggregate base course and subbase or asphalt concrete underlain by plant mix bituminous base course. The design criteria described below was utilized in determining the pavement thicknesses at the site. City of Fort Collins "Design Criteria and Standards for Streets" dated July 1986 and AASHTO Guide for Design of Pavement Structures 1986 18 kip ESAL - 365,000 based on an 18 kip EDLA of 50 provided by the City of Fort Collins Resilient Modulus MR of 3775 psi based on an "R" value of 5 5- Reliability Factor - 90 Overall Deviation - .44 Initial Serviceability Index - 4.5 Terminal Serviceability Index - 2.5 Drainage Coefficient - 1.0 20-Year Design Life Structural Number - 3.67 Strength Coefficients: Asphalt Concrete - 0.44 Plant Mix Bituminous Base Course - 0.34 Crushed Aggregate Base Course - 0.11 Select Subbase - 0.10 The following minimum pavement thicknesses are recommended: Asphalt Concrete 4" Crushed Aggregate Base Course 8" Select Subbase 10" Total Pavement Thickness 22" Asphalt Concrete 3" Plant Mix Bituminous Base Course 7" Total Pavement Thickness 10" The select subbase should meet City of Fort Collins Class 1 specifications, and the crushed aggregate base course should meet City of Fort Collins Class 5 or 6 specifications. The subgrade below the proposed asphalt pavement should be prepared in accordance with the recommendations discussed in the "Site Grading, Excavation and Utilities" section of this report. Upon proper preparation of the subgrade, the subbase and base course should be placed and compacted between optimum moisture and two percent (2%) wet of optimum moisture to at least ninety-five percent (950) of Standard Proctor Density ASTM D 698-78. (See Appendix C. ) It is recommended the asphalt concrete and/or plant mix bituminous base course be placed in two (2) to three (3) inch lifts. All plant mix 6- bituminous base course and asphalt concrete shall meet City of Fort Collins specifications and shall be placed in accordance with these specifications. All subbase material shall have an "R" value between 50 and 69, the crushed aggregate base course shall have an "R" value between 70 and 77, the plant mix bituminous base course shall have an Rt value of 90 or greater, and the asphalt concrete shall have an Rt value of 95 or greater. The "R" value of the pavement materials used should be verified by laboratory tests. Field density tests should be taken in the aggregate base course, bituminous base course, and asphalt concrete under the direction of the geotechnical engineer. Rigid Pavement A feasible pavement alternate at the site would be rigid pavement. Using the eighteen (18) kip equivalent daily load application described above, a modulus of subgrade reaction of one hundred (100) pounds per square inch per inch based on an "R" value of 5, a design life of twenty 20) years, and concrete designed with a modulus of rupture of six hundred fifty (650) pounds per square inch, the following minimum pavement thickness is recommended: Nonreinforced Concrete - 7" Concrete pavement should be placed directly on the subgrade that has been uniformly and properly prepared in accordance with the above recommendations. All concrete used in the paving shall meet ASTM specifications, and all aggregate shall conform to ASTM C 33 specifications. The concrete should be designed with a minimum modulus of rupture of six hundred fifty (650) pounds per square inch in twenty-eight (28) days. It is recommended laboratory mix designs be done to determine the proper proportions of aggregates, cement, and water necessary to meet these requirements. It is essential 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" specifications to ensure good performance of 7- the pavement. It is recommended 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 of Fort Collins specifications should be utilized. The concrete pavement should be properly cured and protected in accordance with the above specifications. Concrete injured by frost should be removed and replaced. It is recommended the pavement not be opened to traffic until a flexural strength of four hundred (400) pounds per square inch is obtained or a minimum of fourteen (14) days after the concrete has been placed. GENERAL COMMENTS This report has been prepared to aid in the evaluation of the property and to assist the engineer in the design of this project. In the event any changes in the street grade or designs 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 Laboratories, Inc., the geotechnical 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 ground water conditions between test borings may be encountered during construction. In order to permit correlation between the reported subsurface conditions and the actual conditions encountered during construction and to aid in carrying out the plans and specifications as originally contemplated, it is recommended Empire Laboratories, Inc. be retained to perform continuous construction review during the subgrade preparation, fill placement, and paving phases 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 subgrade preparation and pavement placement. 8- APPENDIX A o LA 11 E tJo.2 OANAL- FLo LIfJ TEST BORING LOCATION PLAN LA UA E —Sa A-2 EMPIRE LABORATORIES, INC.. - 1347^ e,-Li L'v; P ILLr--e 10-to-I2 KEY TO BORING LOGS TOPSOIL GRAVEL FILL v,: SAND & GRAVEL SILT i+ SILTY SAND & GRAVEL Lai - CLAYEY SILT op COBBLES SANDY SILT s. . o• q SAND, GRAVEL & COBBLES CLAY WEATHERED BEDROCK 0 SILTY CLAY SILTSTONE BEDROCK SANDY CLAY CLAYSTONE BEDROCK aSAND 1 SANDSTONE BEDROCK i. SILTY SAND LIMESTONE CLAYEY SAND x R" x R L GRANITE SANDY SILTY CLAY SHELBY TUBE SAMPLE STANDARD PENETRATION DRIVE. SAMPLER WATER TABLE 0 hrS AFTER DRILLING HOLE CAVED T 5/12 Indicates that 5 blows of a 140 pound hammer falling 30 inches was requires A-3 EMPIRE LABORATORIES. INC. LOG OF BORINGS LE:V14TIofJ •3 493 5 4930 4925 4920 A-4 EMPIRE LABORATORIES, INC. APPENDIX B RESISTRNICE R-VALUE AND EXPRNSION PRESSURE OF COMPACTED SOIL A'LTrl — D 2344 CLIENT: PARSONS '& AS'_OCIATES PROJECT: •JFK' PARKWA`- @ LARIMER CANAL NO. 2 LOCATION OF AMPLE: COMPOSITE SAMPLE BORING NO. 4 is 0. 5' — 4. 0' SAMPLE DATA TEST 'SPEC I MEN 1 2 3 COMPACTION PRESSURE PSI 20 70 160 DEN'SIT`i' — PCF 105.5 108.2 113.3 MOISTURE — . 21.1 18.3 15.6 EXPANSION PRESSURE PSI 0.00 0.00 0.06 HORIZONTAL PRESSURE p 160 psi 155 149 139 SAMPLE HEIGHT — in. 2.52 2.47 2.50 E„UDATION PRESSURE PSI 111 259 458 UNCORRECTED R—VALUE 1.6 3.8 8.4 CORRECTED R—VALUE 1.6 3.8 8.4 R—VALUE AT 300 PSI EXUDAT I iiha PRESSURE = 4.9 1 4_•1 t_9 tl l;•1 W 6 Cl J 2 x I a 4Fj c0 C-i EXUDATIC I',a PRESSURE — p _: i E.."IPIRE LABORRTORI E It, —IC. B-2 O c N CV O m 4 4 LO xg SCC p0 U yV=y w c O LO V 1 Q CL m 11) 0-0 O S T Y xy O CV r-4 17 N C• J M Cn W a H N W LL m M O W N y G m LLIAy `a d m Q CL2 y— cVCmCL O' i e--1 O O Cp O O O O 1 t CV C3 O N r N N O r m CEE cl2OU Cn ME APPENDIX C APPENDIX C. Suggested Minimum Specifications for Placement of Compacted Earth Fill and/or Backfills GENERAL The geotechnical engineer shall be the owner's, architect's, engineer's or contractor's representative to observe placement of compacted fill and/or backfill on the project. The geotechnical engineer or his representative shall approve all earth materials prior to their use, the method of placement and the degree of compaction. MATERIALS Soils used for all compacted fill and backfill shall be approved by the geotechnical engineer or his representative prior to their use. Fill material shall be free from organic matter, frozen material and other unsuitable substance and shall not contain rocks or lumps having a diameter greater than six (6) inches. SUBGRADE PREPARATION All topsoil, vegetation, trees, brush, timber, debris, rubbish and all other unsuitable material shall be removed to a depth satisfactory to the geotechnical engineer or his representative. The material shall be disposed of by suitable means prior to . beginning preparation of the subgrade. The subgrade shall be scarified a minimum depth of six (6) inches, moisture conditioned as necessary and compacted in a suitable manner prior to placement of fill material. Fill shall not be placed until approval by the geotechnical engineer or his representative; and in no case, shall fill material be placed on frozen or unstable ground. Subgrade which is not stable may require the use of imported granular material, geotextiles or other methods for stabilization as approved by the geotechnical engineer. FILL PLACEMENT Fill material shall not be placed during unfavorable weather conditions. Material proposed for use as fill shall be approved by the geotechnical engineer or his representative prior to use. Proposed import material shall be approved by the geotechnical engineer or his representative prior to hauling to the project site. Fill material shall be C-2 uniformly mixed such as to preclude the formation of lenses of material differing from the surrounding material. All clods shall be broken into small pieces. The contractor shall construct the fill in approximately horizontal lifts extending the entire length of the fill. The thickness of the layers before compaction shall not be greater than eight (8) inches. Fill being placed on slopes or hillsides shall be benched into the existing slope. A minimum two (2) foot horizontal bench shall be cut into the existing excavated slope for each four (4) feet vertical of fill, or each lift should be benched slightly into the existing grade. MOISTURE CONTROL Prior to and during compaction operations, the fill material being placed shall be maintained within the range of optimum moisture specified. A general recommendation is to maintain the fill material within two percent (2%) plus or minus of optimum moisture so that proper compaction to the specified density may be obtained with a minimal effort. In building pad and paved areas, material exhibiting swelling potential shall be maintained between optimum moisture and two percent (2%) wet of optimum moisture content. The moisture content of the fill material shall be maintained 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 geotechnical engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. If, in the opinion of the geotechnical 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. Uniform mixing may require discing, blading or other methods approved by the geotechnical engineer or his representative. Adjustments of moisture content shall be made on the basis of determinations of moisture content by field tests as construction progresses. COMPACTION The contractor shall furnish and operate the necessary types and kinds of equipment to perform the operations required to obtain the specified compaction. This equipment may include approved tamping rollers, rubber tired rollers, smooth wheeled rollers and vibratory rollers. If a sheepsfoot roller is used, it shall be provided with cleaner bars so attached as to prevent the accumulation of material between the tamper feet. Fill areas which are not accessible to full-sized construction equipment shall be placed in maximum four (4) inch lifts and compacted with power tampers to the specified density. C-3 Compaction should meet the minimum percentages of maximum density as set forth in the project specifications or the recommendations of the report. The contract specifications supersede the recommendations given in this report. MOISTURE DENSITY RELATIONSHIP DETERMINATION Samples of representative fill materials to be placed shall be furnished by the contractor to the geotechnical engineer for determination of maximum density and optimum moisture or relative density. Sufficient laboratory moisture density or relative density curves will be .made to determine the optimum moisture content and maximum density for the various soils placed as fill. Tests for this determination will be made using the appropriate method conforming to the requirements of ASTM D 698 (Standard Proctor) , ASTM D 1557 (Modified Proctor) or ASTM D 4253, D 4254 (Relative Density).. The materials used for fill shall be classified in accordance with ASTM D 2487 in order to permit correlation between the moisture density relationship data and the material being placed and compacted. Copies of the results of these tests will be furnished to the client and others as directed by the client. These test results shall be the basis of control for all compaction effort. FIELD DENSITY AND MOISTURE TESTS The in -place density and moisture content of compacted fill will be determined by the geotechnical engineer or his representative in accordance with ASTM D 1556 (sand cone method) or ASTM D 2922, D 3017 (nuclear methods). Material not meeting the required compaction and/or moisture specifications shall be recompacted and/or moisture conditioned until the required percent compaction and/or moisture content is obtained. Sufficient compaction tests shall be made and submitted to support the geotechnical engineer's or his representative's recommendations. The results of density tests will also befurnished to the client and others as directed. C- 4