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HomeMy WebLinkAboutLANDINGS OFFICE PARK P.U.D. - PRELIMINARY - 10-95 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTLOG OF BORING No. 3 Page 1 of 1 CLIENT Lagunitas Company ARCHITECT/ENGINEER SITE Broadwalk & Landings Drive Fort Collins, Colorado PROJECT Proposed Office Park H = EL 2 M (9 DESCRIPTION LL 2 F- 1L W O cc > Lo U w 7 SAMPLES TESTS W to L Z W (L T F- w > O U W M Z\ 1 N 3 F- O 0_J wM M 1- (n H O S w O >_ LL D:U On. ?_ Z Z O W U R LL ZF-(n O(nd J (A J(n W W LL =62m (nao- 0.5 FILL -Sandy lean rev with gr�hard rown, dry 5 10 CL 1 SS 12" 27 7 135 850 SANDY LEAN CLAY Tan, dry to moist, stiff 4.5 CL 1 ST 12" 11 85 2 SS 8" 31 15 WEATHERED CLAYSTONE/ 5.5 SILTSTONE Tan, moist, moderately hard Ci _AYSTONE/SILTSTONE Gray/tan, moist, hard 14.7 BOTTOM OF BORING 3 SS 11" 50111 14 4 SS 10" 50/10 13 THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Tecracon BORING STARTED 10-5-94 wL Q None W.D. s None A.B. BORING COLLETED 10-5-94 WL RIG CME-55 FOREMAN DML WL Water checked 1 day A.B. APPROVED NRS JOB Y 20945233 i I LOG OF BORING No. 2 Page 1 of 1 CLIENT Lagunitas Company ARCHITECTIENGINEER SITE Broadwalk & Landings Drive Fort Collins, Colorado PROJECT Proposed Office Park L) = (L LD DESCRIPTION 2 F a. M J y fA L) SAMPLES TESTS W in 1: z W d W > O U W Z\ IN 3 1-0 Cnno \ j H in H E } z O y.Iy oa H� ZZ O W UQ'LL :3W(L W JN J (n WWLL v3iad FILL -Sandy lean clay with gravel 1.5 Brown, dry, hard 5 10 1 SS 12" 32 12 420 SANDY LEAN CLAY Tan, dry, stiff 3.5 CL 1 ST 12" 8 WEATHERED SANDSTONE 4.5 Tan, moist, cemented 2 SS 8" 50/8 8 — SANDSTONE Gray/tan, moist, well cemented 14.3 _ 3 SS 7" 50/7 11 — — 4 SS 4" 50/4 11 BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Terracon BORING STARTED 10-5-94 g None W.D.i None A.B. BORING COMPLETED 10-5-94 WL IW RIG CME-55 FOREMAN DML wI Water checked 1 day A.B. APPROVED NRS Job q 20945233 LOG OF BORING No. 1 Page 1 of 1 CLIENT Lagunitas Company ARCHITECTIENGINEER SITE Broadwalk & Landings Drive Fort Collins, Colorado PROJECT Proposed Office Park o 0 J H = d V, DESCRIPTION .. U- 2 H a. W O o E } N O V to 7 SAMPLES TESTS W co E O Z W IL H Y z � O L) W C g LL Z\ I N 3 F-O 0--1 rA n7 � W ix I— U1 H O L > N z O >-LL =V Od c ZS H �- Z Z O W U=Lt. ZHfA 7U70. W 0: J (n JfA www 3Q2cn NILC- 0.5 FILL -Sandy lean rla� with g�very�stiff_.�� rown, dry, 5 10 CL 1 SS 12" 17 2 1040 SANDY LEAN CLAY Tan, dry, stiff 3.5 CL 1 ST 12" 11 WEATHERED CLAYSTONE/ SILTSTONE 5.0 Gray/tan, moist, moderately hard 2 SS 12" 34 9 C AYSTONF/SILTSTONE Gray/tan, moist, hard 8.0 = SANDSTONE/SILTSTONE Tan, moist, well cemented, hard 14.5 3 SS 9" 50/9 11 _= — 4 SS 5" 5015 10 E BOTTOM OF BORING THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL. WATER LEVEL OBSERVATIONS Empire Laboratories Incorporated Division of Terrecon BORING STARTED 10-5-94 WL g None W.D.IT None A.B. BORING COMPLETED 10-5-94 WL RIG CME-55 FOREMAN DMEL WL Water checked 1 day A.B. APPROVED TV_ JOB " 20945233 o.� y L I (Sl j �K 1�=-- I : 5 171--' FL A� �-1 vaizb�.l�Lk i LAOPINJ6016 ro}2Tc�� �� f\JS, Gu�o�tp.k7© r,Li• �Jo• 2di45233 Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. No Text I 11 II Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 eliminating the potentially detrimental effects of floor movement in these areas. However, if the owner is willing to assume the risk of possible slab movement, slab -on -grade construction may be a reasonable alternative. In the western portion of the site, low expansive soils and bedrock or engineered fill will support the floor slab. Some differential movement of a slab -on -grade floor system is possible should the subgrade soils become elevated in moisture content. Such movements are considered within general tolerance for normal slab -on -grade construction. • Compliance: Recommendations for slabs -on -grade,. foundations and pavement elements supported on compacted fills or .prepared subgrade depend upon compliance with "Earthwork" recommendations. Additional geotechnical and earthwork recommendations should be provided prior to final design and construction. To assess compliance, observation and testing should be performed under the direction of the geotechnical engineer. PRELIMINARY GENERAL COMMENTS It should be noted that this was a preliminary investigation and the foundation systems recommended in this report are based on preliminary tests. Due to variations in soil conditions encountered at the site, it is recommended that additional test borings be made prior to final design. Samples obtained from the borings should be tested in the laboratory to provide a basis for evaluating subsurface conditions. 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 engineering practices. No warranty, express or implied, is made. This report has been prepared to aid in the evaluation of the property and to assist the architect and/or engineer in the preliminary design of this project. This report is for the exclusive purpose of providing preliminary geotechnical engineering and/or testing information and recommendations. The scope of services for this project does not include, either specifically or by implication, any environmental assessment of the site or identification of contaminated or hazardous materials or conditions. If the owner is concerned about the potential for such contamination, other studies should be undertaken. 7 Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 3. If excavations need to penetrate the well -cemented sandstone, blasting may be needed to facilitate rock break up and removal. 4. Groundwater seepage should be anticipated for excavations approaching the level of the bedrock. Pumping from sumps may be utilized to control water within the excavations. Well points may be required for significant groundwater flow or where excavations penetrate groundwater to a significant depth. • Fill Materials: 1. On -site bedrock materials are not recommended for use beneath structural ares of the site, or as backfill. Should bedrock materials be used for general site grading, placement in fills at non-structural • locations on the site is recommended. Foundation Systems: Due to the presence of moderately to highly expansive siltstone- claystone bedrock on the site, a grade beam and drilled pier foundation system is recommended for support of the proposed structures founded in or within 3 feet of the expansive siltstone-claystone bedrock. Straight shaft piers, drilled a minimum of 3 feet into the firm or harder bedrock with a minimum shaft length of 10 feet, should be anticipated. Due to the presence of low swelling soils and sandstone bedrock in the western portion of the site, spread footing foundations bearing upon sandstone, undisturbed soils and/or i engineered fill are recommended for support of proposed structures in the western portion of the site. Additional testing should be done prior to final design after building locations have been finalized. Perched groundwater may occur at times since the subsurface soils are relatively impermeable and tend to trap water. Completion of site development, including installation of landscaping and irrigation systems, will likely lead to perched groundwater development. Floor Slab Design and Construction: The variability of the existing soils at approximate slab subgrade elevation could result in differential movement of floor slab -on -grade should expansive siltstone-claystone become elevated in moisture content. Use of structural floor systems, structurally supported independent of the subgrade soils, is a positive means of 0 Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS Site Development Considerations: The site appears suitable for the proposed construction. • Site Clearing: 1. Strip and remove existing vegetation, debris, and other deleterious materials from proposed building and pavement areas. All exposed surfaces should be free of mounds and depressions which could prevent uniform compaction. 2. If unexpected fills or underground facilities are encountered during site clearing, such features should be removed and the excavation thoroughly cleaned prior to backfill placement and/or construction. All excavations should be observed by the geotechnical engineer prior to backf ill placement. 3. Stripped materials consisting of vegetation and organic materials should be wasted from the site, or used to revegetate exposed slopes after completion of grading operations. 4. Demolition of the existing buildings should include removal of any foundations. All material derived from the demolition of existing structures should be removed from the site and not be allowed for use in any on -site fills. 5. All exposed areas which will receive fill should be scarified to a minimum depth of 8 inches, conditioned to near optimum moisture content, and compacted. • Utility and Site Grading: 1. It is anticipated that excavations in the upper subsoils and weathered bedrock for the proposed construction can be accomplished with conventional earthmoving equipment. 2. Excavations penetrating the bedrock may require the use of specialized heavy-duty equipment, such as a large track -mounted backhoe. 5 Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 0 Claystone-Siltstone-Sandstone Bedrock: The bedrock was encountered at depths of 3'/z to 4'/2 feet below the surface. and extends to greater depths. The bedrock in Boring 1 consists of claystone-siltstone underlain by sandstone. The sandstone was encountered below the upper soils in Boring 2, and claystone-siltstone was encountered below the upper subsoils in Boring 3. The underlying firm bedrock is hard and well cemented. Field and Laboratory Test Results: Laboratory test results indicate the clay subsoils are dry to moist and stiff and exhibit low swell potential and low to moderate bearing characteristics. The siltstone-claystone bedrock exhibits moderate to high swell potential, and the sandstone-siltstone-claystone exhibits high to very high bearing characteristics. Groundwater Conditions: Groundwater was not encountered in the test borings at the time of field exploration nor when checked one day after drilling. These observations represent only current groundwater conditions, and may not be indicative of other times, or at other locations. Groundwater levels can be. expected to fluctuate with varying seasonal and weather conditions. Based upon review of U.S. Geological Survey Maps ('Hillier, et al, 1983), regional groundwater beneath the project area predominates in colluvial, landslide or windblown materials, or in fractured weathered consolidated sedimentary bedrock located at a depth near ground surface. Seasonal variations in groundwater conditions are expected since the aquifer materials may not be perennially saturated. Groundwater is generally encountered at depths ranging from 5 to 20 feet below ground surface; depth to seasonal groundwater is generally 10 feet or less. Zones of perched and/or trapped groundwater may also occur at times in the subsurface soils overlying bedrock, on top of the bedrock surface or within permeable fractures in the bedrock materials. The location and amount of perched water is dependent upon several factors, including hydrologic conditions, type of site development, irrigation demands on or adjacent to the site, fluctuations in water features, seasonal and weather conditions. 'Hillier, Donald E.; Schneider, Paul A., Jr.; and Hutchinson, E. Carter, 1983, Depth to Water Table 119791 in the Bou/der-Fort Collins -Greeley Area, Front Range Urban Corridor, Colorado, United States Geological Survey, Map 1-855-1. 4 Preliminary Geotechnical Engineering Exploration Lagunitas Company ELI Project No. 20945233 Terracon laboratory tests were performed in general accordance with the applicable ASTM, local or other accepted standards. SITE CONDITIONS A mobile home is located on the east half of the site, and an existing house is located in the west portion of the area. Several outbuildings and fenced dog pens are also located on the property. The site is vegetated with sod, native grasses and several large trees. The area slopes to the south toward Boardwalk Drive and has positive drainage in this direction. The property is bordered to the west, north and east by fences, to the south by Boardwalk Drive, and to the east by Landings Drive. SUBSURFACE CONDITIONS Geology: The proposed area is located within the Colorado Piedmont section of the Great Plains physiographic province. The Colorado Piedmont, formed during Late Tertiary and Early Quaternary time (approximately 2,000,000 years ago), is a broad, erosional trench which separates the Southern Rocky Mountains from the High Plains. Structurally, the site lies along the western flank of the Denver Basin. During the Late Mesozoic and Early Cenozoic Periods (approximately 70,000,000 years ago), intense tectonic activity occurred,. causing the uplifting of the Front Range and associated downwarping of the Denver Basin to the east. Relatively flat uplands and broad valleys characterize the present-day topography of the Colorado Piedmont in this region: The site is underlain by the Cretaceous Pierre Formation. The Pierre shale consisting of sandstones, siltstones and claystones underlies the site at depths of 3 % to 4'/z feet below the surface. The Pierre shale is overlain by residual soils of Pleistocene and/or Recent Age. Soil and Bedrock Conditions: As presented on the Logs of Boring, the subsurface soils are presented as follows: • Fill Material: A '% to 1'% foot layer of fill material was encountered at the surface of the three borings drilled at the site. The fill consists of sandy lean clay with minor amounts of gravel. The fill is dry and very stiff to hard. • Sandy Lean Clay: This stratum underlies the fill and extends to the bedrock below. The sandy lean clay is moderately plastic, is dry to moist and stiff in consistency. 3 .1 Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 Field Exploration: A total of three test borings were drilled on October 5, 1994 to approximate depths of 14 to 14'/a feet at the locations shown on the Site Plan, Figure 1. The borings were drilled within the area of the proposed building construction. All borings were advanced with a truck -mounted drilling rig, utilizing 4-inch diameter solid stem auger. The borings were located in the field by pacing from existing fence lines. The accuracy of boring locations should only be assumed to the level implied by the methods used. Continuous lithologic logs of each boring were recorded by the engineering geologist during the drilling operations. At selected intervals, samples of the subsurface materials were taken by pushing thin -walled Shelby tubes, or by driving split -spoon samplers. Penetration resistance measurements were obtained by driving the split -spoon into the subsurface materials with a 140-pound hammer falling 30 inches. The penetration resistance value is a useful index to the consistency, relative density or hardness of the materials encountered. Groundwater measurements were made in each boring at the time of site exploration, and one day after drilling. 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. �j At that time, the field descriptions were confirmed or modified as necessary, an applicable J laboratory testing program was formulated to determine engineering properties of the. subsurface materials. Boring logs were prepared and are presented in Appendix A. Selected soil and bedrock samples were tested for the following engineering properties: • Water content • Expansion • Dry density • Atterberg limits • Consolidation • Water soluble sulfate The significance and purpose of each laboratory test is described in Appendix C. Laboratory test results are presented in Appendix B, and were used for the geotechnical engineering analyses, and the development of foundation and earthwork recommendations. All 2 I PRELIMINARY GEOTECHNICAL ENGINEERING REPORT MASTERS PROPERTY FORT COLLINS, COLORADO ELI Project No. 20945233 November 4, 1994 INTRODUCTION Terracon This report contains the results of our preliminary geotechnical engineering exploration for the proposed office buildings to be located on Boardwalk Drive between JFK Parkway and Landings Drive in south Fort Collins, Colorado. The site is located in the Southwest 1 /4 of Section 36, Township 7 North, Range 69 West of the 6th Principal Meridian. The purpose of these services is to provide information and preliminary geotechnical engineering recommendations relative to: • subsurface soil and bedrock conditions • groundwater conditions • site development considerations • preliminary foundation design and construction •. preliminary floor slab design and construction J• utilities The conclusions and recommendations contained in this report are based upon the results of field and laboratory testing, engineering analysis, and experience with similar soil conditions, structures and our understanding of the proposed project. PROPOSED CONSTRUCTION The site is to be developed as a commercial office park with several one- or two-story slab - on -grade office buildings proposed for the site. Parking areas and/or drives are planned adjacent to the buildings. Site grading plans were not available prior to preparation of this report. However, it is anticipated that cuts and fills will be less than 3 to 4 feet throughout 1 the project area. SITE EXPLORATION The scope of the services performed for this project included site reconnaissance by an engineering geologist, a subsurface exploration program, laboratory testing and engineering analysis. Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 TABLE OF CONTENTS (Cont'd) APPENDIX A Figure No. SitePlan ................................................. 1 Logs of Borings ..................................... Al thru A3 APPENDIX B Consolidation Test ......................................... 131 Summary of Test Results .................................... B2 APPENDIX C: GENERAL NOTES Drilling & Exploration ....................................... C1 Unified Soil Classification .................................... C2 Bedrock Classification, Sedimentary Bedrock ....................... C3 Laboratory Testing, Significance and Purpose ...................... C4 Report Terminology ...........................:............ C5 Preliminary Geotechnical Engineering Exploration Terracon Lagunitas Company ELI Project No. 20945233 TABLE OF CONTENTS Page No. Letter of Transmittal ............................................... ii INTRODUCTION................................................ 1 PROPOSED CONSTRUCTION ...................................... 1 SITE EXPLORATION ............................................. 1 Field Exploration .......................................... 2 Laboratory Testing ......................................... 2 SITE CONDITIONS .............................................. 3 SUBSURFACE CONDITIONS ....................................... 3 Geology................................................ 3 Soil and Bedrock Conditions .................................. 3 Field and Laboratory Test Results ............................... 4 Groundwater Conditions .............. 4 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS .................. 5 Site Development Considerations ............................... 5 Site Clearing ........................................ 5 Utility and Site Grading ................................. 5 Fill Materials ........................................ 6 Foundation Systems ........................................ 6 Floor Slab Design and Construction 6 Compliance......................................... 7 PRELIMINARY GENERAL COMMENTS ................................ 7 7 Preliminary Geotechnical Engineering Exploration Lagunitas Company ELI Project No. 20945233 Terracon Other design and construction details, based upon geotechnical conditions, are presented in the report. We appreciated being of service during the preliminary geotechnical engineering phase of this project, and are prepared to assist during the final geotechnical and construction phases as well. If you have any questions concerning this report or any of our testing, inspection, design and consulting services, please do not hesitate to contact us. Sincerely, \�S1�f.�NorATE,p �'4�••��c EMPIRE LABORATORIES, INC. ��i �� 2575 BF9 A Division of The Terraco ompanies, Inc. _ AIPG Ne11 R.pNpQ�o�A Senior Engineering Geologist m Reviewed b \��a�ulluururi RE CAI . •c �t . opF F�F Larry G. O'Dell, P.E. = o t 22750 Office Manager:, �°' "/ONIAi,� NRS\LGO\cic — Copies to: Addressee (3) iii Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. P.O. Box 503.301 No. Howes Fort Collins, Colorado 80522 (303) 484-0359 Fax (303) 484-0454 ChesterC. Smith, P.E. Larry G. O'Dell, P.E. Neil R. Sherrod, C.P.G. November 4, 1994 Lagunitas Company 3303 South College Avenue, Suite 200 Fort Collins, Colorado 80525 Attn: Mr. John Prouty Re: Preliminary Geotechnical Engineering Report, Masters Property, Fort Collins, Colorado ELI Project No. 20945233 Empire Laboratories, Inc. (ELI) has completed a preliminary geotechnical engineering exploration for the proposed office park to be located on Boardwalk Drive between Landings Drive and JFK Parkway in southwest Fort Collins, Colorado. This study was performed in general accordance with our proposal number D2094254 dated September 29, 1994. The results of our engineering study, including the boring location diagram, laboratory test results, test boring records, and the preliminary geotechnical recommendations needed to aid in the preliminary design and earth connected phases of this project are attached. The subsurface soils consisted of sandy lean clay underlain by claystone-siltstone-sandstone bedrock. The information obtained by the results of field exploration and laboratory testing completed for this study indicates the soils at the site have low expansive potential and the siltstone-claystone bedrock exhibits moderate to high swell potential. The soils exhibit moderate bearing characteristics, and the bedrock exhibits high bearing characteristics. Based on the geotechnical engineering analysis, subsurface exploration and laboratory test results, we recommend the proposed structures founded in or within 3 feet of the expansive siltstone-claystone bedrock be supported on a grade beam and straight shaft pier foundation system. Structures founded in the sandstone bedrock or upper soils underlain by sandstone bedrock may be supported by spread footing foundations. Due to the engineering characteristics of near surface soil and bedrock, it is our opinion that if no movement can be tolerated, structural floor systems should be considered. Slab -on -grade may be utilized for interior floor systems provided the owner is willing to accept the risk of movement and care is taken during placement and compaction of the subgrade soils. Offices of The Terracon Companies, Inc. Geotechnical, Environmental and Materials Engineers Arizona Arkansas 0 Colorado 0 Idaho fill Illinois 0 Iowa 0 Kansas E Minnesota Missouri Montana N Nebraska N Nevada 0 Oklahoma 0 Texas 0 Utah N Wyoming GIIAI ITV ENGINEERING SINCE 1965 PRELIMINARY GEOTECHNICAL ENGINEER MASTERS PROPERTY FORT COLLINS, COLORADO ELI PROJECT NO. 20945233 November 4, 1994 REPORT Prepared for. LAGUNITAS COMPANY 3303 SOUTH COLLEGE AVENUE, SUITE 200 FORT COLLINS, COLORADO 80525 ATTN: MR. JOHN PROUTY Prepared by. Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. 301 North Howes Fort Collins, Colorado 80521 Empire Laboratories, Inc. A Division of The Terracon Companies, Inc. PRELIMINARY GEOTECHNICAL ENGINEERING REPORT MASTERS PROPERTY FORT COLLINS, COLORADO ELI PROJECT NO. 20945233 November 4, 1994 A Division of The Terracon Companies, Inc.