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HomeMy WebLinkAboutReport of Foundation InvestigationREPORT Or FOUNDATION INVESTIGATION PROPOSED SERVICE CENTER - RAILROAD AVENUE AND SECOND STREET, RIFLE, COLORADO FOR PUBLIC SERVICE COMPANY OF COLORADO 8142-019-14 AIiCIIORAGC Loa AUG [LES ATIAItTA TIC%'/ VORA CIIICAOO POIIILAI10 CHIC IIIIIAII Gat! LANC CITY OCI+VCR SAIL IRAIItISCO IIOtIOLULU SCATTLC Mou-�IOR 1'+Ayt1111GTu11. C. C erlit GOIl ULTlu4 CRGItICCRG iil TIIC APPLIC4 'GARTH OCILIiCC3 CALGARY GCPUI GUAR SIIIOAPOOL lolluoii -1lu11CT i1A0010 TCRPAiU PERTH 1OROIIIQ 'A11COUVCR, A C SUITE 100, 10597 WEST 6'11 AVENUE • DENVER, COLORA00 80215 • (3031 232-6262 TVX: 910-931-2600 April 9, 1973 Public Service Company of Colorado Structural Engineering Department 5900 East 39th Avenue Denver, Colorado 80207 Attention: Mr. H. W. Hight Gentlemen: Six copies of our report entitled, "Foundation Investigation, Proposed Service Center, Railroad Avenue and Second Street, Rifle, Colorado, For Public Service Company of Colorado" are herewith submitted. The purpose and scope of this investigation were planned in diacusaions between Mr. Svenn Borgersen of Public Service Company and Mr. Larry Davidson of Dames & Moore. A summary of the purpose of the scope of this study was outlined in Extra Work Authorization No. 19 dated March 27, 1973. The results of our investigation indicate that the proposed service center building and associated pavement areaa may be satis- factorily supported on the in-situ soils at the site. Deep filt was encountered over the eastern portion of the site, and special foundation design considerations are necessary to provide uniform foundation support in this area. The pavement may be constructed directly upon the existing soils at all Locations. Detailed recommendations regarding site preparation, excavations, foundations, floor slabs, pavement design and site grading are presented in the attached report. We appreciate the opportunity of performing this investi- gation for you, If you have any questions concerning this report or if you require additional information please contact ue. LKDJ lb Very truly yours; DAMES & MOORE . Larry, Davidson y Associate } . FOUNDATION INVESTIGATION PROPOSED SERVICE CENTER RAILROAD AVENUE AND SECOND STREET RIFLE, COLORADO FOR PUBLIC SERVICE COI4PANY OF COLORADO INTRODUCTION This report presents the results of our foundation investigation for the proposed service center and associated paved areas to be con- structed in Rifle, Colorado. The location of the site and planned con- struction with respect to existing streets is shown on Plate 1, Plot. Plan. PURPOSE AND SCOPE The purpose of this investigation is to provide design recommenda- tions for constructing foundations, floor slabs, and pavement at the pro- posed site. To accomplish this purpose the following scope of work was performed. 1) A field investigation program consisting of excavating, logging and sampling five test pits. 2) Laboratory testing. 3) Engineering analyses. 4) Preparation of this written report which includes: a) Piot plan showing boring locations b) Test pit logs c) Recommendations for site preparation, excavations, foundations, floor slabs, pavement and site grading. r ,PAVAE5 0 1+400ne SUBSURFACE As mentioned in the previous paragraph most of the site has been covered with fill. This fill ranges in thickness from less than a foot over portions of the western two-thirds of the site to a maximum of approximately eight feet on the extreme eastern side of the site. The fill coneimts of a medium stiff, broom, clayey silt with some fine sand. At Test Pits 2 and 3, where the fill is the deepest, the fill grades less clayey with depth but also contains occasional thin zones of miscellaneous debris including asphalt, cinders, and lumber. The fill was never compacted but some stiffening has occurred due to surface traffic and settlement. The results of our laboratory testa indicate that the fill material is moderately compressible and somewhat moisture sensitive, showing an increase in compressibility with the addition of moisture. At all the test pit locations, the fill material is underlain by an alluvial medium dense, brown, sandy fine to coarse gravel with some cobbles. This material is the original soil at the site. With depth, the gravel material grades coarser and in Test Pits 2 and 3 the gravel layer is grayish brown in color and contains some clay. In Test Pit 3, the gravel stratum is overlain by a 1-1/2 foot thick layer of medium stiff, brown, silty clay with some fine gravel. This clay layer appears to be natural soil. GROUNDWATER Groundwater was not encountered in any of the teat pits at the site. DISCUSSIONS AND RECOMMENDATIONS GENERAL Based on our field explorations, laboratory testing and engineering analyses, it is our opinion that the proposed service center and pavement may be satisfactorily supported on the in-situ soil at the site. Because DAMES e R1001121 la -4 - of the Loosely dumped fill which has been placed on the eastern one third of the site, special design considerations are necessary for foundations in this area. Otherwise, no major construction problems are anticipated. Groundwater was not encountered in the Test Pits and should not be a.pro- blem: Detailbd.site preparation,'excavation;:foundation, floor slab; . .pavemcnt'deeign and site grading.recormnendations are provided in the following paragraphs. SITE PREPARATION Prior to our field investigation program the site had been cleared of all surface structures and surface vegetation. Therefore, no site preparation, other than removal of whatever debris may exist on the site at the time of construction, will be necessary before beginning construction of foundations, floor slabs and pavement. EXCAVATIONS The soil conditions at the site are such that for shallow excavations, four feet deep or leas, vertical sidewalls may be used. However, for deeper excavations we recommend either sloping the side walls at one horizontal to one vertical or flatter, or the use of adequate shoring. FOUNDATIONS Conventional continuous wall and spread foundations may be used to support the proposed service center, For frost protection we recommend that all exterior foundations be established at a minimum depth of 3-1/2 feet below lowest adjacent final grade. All footings should be founded upon the sand, gravel and cobble stratum underlying the fill material at the site. For most of the service center building, the footing depth requirement for frost protection will also meet the requirement for bearing upon granular soil. The northeast portion of the building will be situated in an area where the gravel stratum is approximately 6 to 8 feet below the ground surface. In this area the foundations may either be extended down to the reAN7ES ti IVIOOR6 -5 - underlying gravel stratum or the fill materials may be excavated and re- placed with compacted, free -draining granular fill. If replacement fill is used only beneath the footings, it should extend laterally beyond the edges of the footings to a distance equal to the depth of the replacement fill beneath the foundation. For instance, if 4 feet of replacement fill were required beneath the foundations, then the minimum width of the re- placement fill should be 8 feet plus the width of the foundation. It may be more economical to use larger equipment and place compacted granular fill beneath the entire northeast portion of the build- ing, rather than individual footings. The area of fill should extend ver- tically to the underlying gravel stratum and horizontally beyond the per- imeter footing edges to a distance equal to the depth of fill. Granular fill used for foundation support should be placed in lifts with a maximum of 8 inches in loose thickness and compacted to 95 percent of maximum dry density, as determined by the AASHO* T-180 Method of Compaction. Vibra- tion drum rollers or plate compactors are most effective for compacting granular materials. For footings supported on compacted granular fill or the sand, gravel, and cobble stratum, we recommend using a minimum footing width of 18 inches and a maximum net bearing pressure of 4,000 paf for design. The weight of the foundation below grade may be ignored in calculating footing loads. We anticipate that the total and differential settlements of footings designed in accordance with our recommendations will be neg- ligible, and should occur during construction and immediately after initial loading. * American Association of State Highway Officials nAmets a rapobrzz13 -6 - FLOOR SLABS The fill soil at the site will provide adequate floor slab sup- port. We recommend that all floor slabs be underlain by a minimum of 4 inches of free -draining, granular fill. This fill should be compacted to 95 percept of the maximum dry density as determined by the modified AASHO T-180 Method of Compaction. The floor slabs should be structurally separated from the columns and walls to allow for any differential settle- ment. PAVEMENT The pavement areas for the proposed site may be constructed directly upon the existing fill at the site, provided the appropriate subgrade preparation is completed. This preparation should include re- moval of soil to the specified grade and compaction of the upper 8 inches of the subgrade. The subgrade should be compacted to the same criteria as mentioned previously for fill beneath the building floor slabs. If during the compaction or stripping process any areas with organic debris or wet or pumping soils are encountered, the deleterious material or soil should be completely removed and replaced with free-draining,compacted, granular fill. From discussions with Public Service Company personnel, we understand that heavily -loaded trucks will be used on the site. We recom- mend the following pavement section for the support of heavily -loaded truck traffic: 1) 3k inches asphalt surface course; 2) 12 inches -- base course fill on top of compacted sub - grade. For areas subjected to car or light utility truck traffic, we recommend a thinner and more economical pavement section consisting of the follow- ing: Wna-Ms e M, OORE - 7- 1) 2 inches -- asphalt surface course; 2) 6 inches -- base course fill on top of compacted sub - grade. SITE GRADING Any of the soils at the site may be used for eite leveling and grading purposes. We recommend that the site be graded so that surface runoff water will be directed away from the building. Adequate surface drainage should be provided from the pavement areas. Fill placed for site grading should be compacted to 90 percent of maximum density as determined by the AASHO T-180 Method of Compaction. The following plate and appendix are attached and complete this report. LID/lb Plate 1, Plot Plan Appendix, Field Explorations and Laboratory Tests Very truly yours, DAMES & MOORE Larr 'K. Davidson Associate DA 4:l 1n Ex Vicars SECOND srREET� ( SERVICE CENTER DOCK — DOCK COVERED PARKING AREA 1 �4 1 �lnP e5 DAMES s YOORE BORING LOCATION 5 E i. ASPHALT PAYING •3 7 1 ID 0 10 10 DO PEET PLATE 1 APPENDIX FIELD EXPLORATIONS AND LABORATORY TESTS FIELD EXPLORATIONS The subsurface soil conditions at the proposed site were investi- gated by excavating 5 test pits to a depth of approximately 12 feet. The test pita were excavated with a rubber -tire, tractor mounted backhoe. The locations of the test pita with respect to the planned site development and site foundations are shown on Plate 1, Plot Plan in the text of this report. The field exploration program was conducted and supervised by an experienced soils engineer from our office. Representative soil samples were obtained from the test pits using a Dames & Moore soils sampler as shown on Plate A-3 Soil Sampler Type U, and hand sampling techniques. The soils encountered were classified by visual and textural examination in the field and a complete log was maintained for each test pit. These classi- fications were supplemented by inspection and testing in our laboratory. Because hand sampling techniques were employed, no blow counts data could be obtained. A graphical representation of the soils encountered is pre- sented on the test pit logs, Plates A -1A to A -1E, Log of Teat Pits. The nomenclature used to describe the soil types appears on Plate A-2, Unified Soil Classification System. LABORATORY TESTS Because of the coarse granular characteristics of most of the on-site soils and hand sampling techniques, our laboratory testing program was minimized. However, we were able to perform a moisture and density determination and consolidation test on one of the fill clayey silt samples. The results of the moisture and deneity•determinations and the consolidation testa are shown on Plate A-4, Consolidation Teat Data. The consolidation test was performed in accordance with the method described on Plate A-5, Method of Performing Consolidation Teats. DAMES B MOOn@ W a A 1 0 W 4i t 946.7 (REV. 6-61} W W z H w d 1 4 0 5 BORING 3 ML lid CL GP GC BROWN CLAYEY SILT WITH SOME FINE SAND (FILL) - MEDIUM STIFF GRADING - TRACE OF CLAY BROWN SILTY CLAY WITH SOME FINE GRAVEL - MEDIUM STIFF GRAYISH -BROWN FINE TO COARSE GRAVEL WITH SOME COBBLES AND CLAY - MEDIUM DENSE GROUNDWATER NOT ENCOUNTERED BORING 4 BROWN SAND FINE TO COARSE GRAVEL WITH COBBLES - MEDIUM DENSE GRADING COARSER SIZES GROUNDWATER NOT ENCOUNTERED LOG OF BORINGS asr,ewED B NVIOORE PLATE A -1B w Q W J 4 946.7 (REV. 6-63) 0 BORING 5 ML 0 GP a • BROWN CLAYEY SILT WITH SOME FINE SAND - MEDIUM STIFF BROWN SAND FINE TO COARSE GRAVEL WITH COBBLES GRADING COARSER SIZES GROUNDWATER NOT ENCOUNTERED LOG OF BORINGS 0,64141ES 8 INIODRItE PLATE A-10 FORA NO. 467.1 L MAJOR DIVISIONS GRAPH SYMBOL LETTER SYMBOL TYPICAL DESCRIPTIONS COARSE SOILS MORE THAN SOX IOff MATERIAL IS 200 SIEV[ S1ZG• ANDS GRAVELLY SOILS YORC THAN SO}; OF COARSE FRAC- T10M R�T LP OH REIFI SKYE CLEAN GRAVELS (LITTLE OR NO rotas) z.. w':,61 %-�•r I ~ r . GW HELL -GRADED GRAVELS, GRAVEL - SAND VIUTUR(S. LITTLE OR NO FINES 11 :7E::7I::R:• ::t j':::� 4 GP ` POORLY -GRADED CRAVELS,GRAVEL- OAHU MIXTURES. LITTLE OR NO FINES GRAVELS WITH PITIES (APPRccIAGL[ OUST Or FINES 1 !i GM SILTY ORAV(LS, GRAVEL-SAND- SILT MIXTURES �/. / GC CLAYEY GRAVELS, GRAVEL-SAHD- CLAY UIRTURES Ail SA1DY SOILS MORE THAN SOX Of COARSE FRAC- 11011 PASSINQ N0. 4 S KYE CLEAN SOD (L1 [TLE 0R NO FINES) •��r'••.••• �AND �' „�••�•; •.i N g t W -J z 94o./ {NEV. b -61J IMF I4G pRtVMECHANISSM�IN6 COUPLING NATER OUTLE NOTCHES FOR ENGAGIING FISHING 00L — NEOPRENE GASKET -- - :. s51. ` CHECK VALVES HEAD __-- VALVE CARE HO 7 C, 'HEAD EXTENSION' CAN RE INTRODUCED BETWEEN 'MEAD" AND 'SPLIT BARREL" SPLIT BARREL JO FACILITATE ELOYAI OF CORE SANPL BIT U. 5. PATENT NO.2, 358,062 SPACE TO RECEIVE DISTURBED SOIL CORE•RETAIHER RINGS I24h'0.0. BY I"LONGI ALTERNATE ATTACHMENTS SPLIT BARREL. LOCKING RING SPLIT FERRULE THIN -MALLEO SAMPLING TUBE CORE•RETAIHING 11NTCRCHAN DEVICE LENGTHS) RETAINER RING RETAINER $ {INTERC HAH0(ABL 1 WITH O SOIL SAMPLER TYPE U COR E•RE TAMING DEVICE IDAIPAllail 8 iYIIDolR11E PLATE A-3 N z 0 N w a w 1- a c I I 0 0 10 �0 t•- UJ w 4 a 0 0 >- >- a) 0 CHECKED BY 746.1 COPY TO EO 0099B 00002 00001 0004 000p tL g 000E vi ▪ 000Z z 0001 taa to co w cc a 00 00 00 00 00 1 1 1 1 TEST PIT 2 AT 1' BROWN CLAYEY SILT WITH SOME FINE SAND MOISTURE CONTENT 17% DRY DENSITY 104 PCF 1 I i I I SAMPLE SATURATED 1 - O Al 0 0 d d d HMI,/ S3HONI NI O d O NOI1V0110SNOO N O DAMES 0 MOOR PLATE A-4 a a 0 1-- 0 W 1- CONSOLI DATION w (r} a r 1 4 946.7 (REV. 5.61) CONSOLIDATION TESTS ARE PERFORMED TO EVALUATE THE VOLUME CHANGES OF SOILS SUBJECTED TO INCREASED LOADS. TIME -CONSOLIDATION AND PRESSURE -CONSOLIDATION CURVES MAY BE PLOT- TED FROM THE DATA OBTAINED IN THE TESTS. ENGINEERING ANALYSES BASED ON THESE CURVES PERMIT ESTIMATES TO BE MADE OF THE PROBABLE MAGNITUDE AND RATE OF SETTLEMENT OF THE TESTED SOILS UNDER APPLIED LOADS. EACH SAMPLE IS TESTED WITHIN BRASS RINGS TWO AND ONE- HALF INCHES IN DIAMETER AND ONE INCH IN LENGTH. UNDIS- TURBED SAMPLES OF IN-PLACE SOILS ARE TESTED IN RINGS TAKEN FROM THE SAMPLING DEVICE IN WHICH THE SAMPLES ' WERE OBTAINED. LOOSE SAMPLES OF SOILS TO BE USED IN CONSTRUCTING EARTH FILLS ARE COMPACTED IN RINGS TO PREDETERMINED CONDITIONS AND TESTED. IN TESTING, THE SAMPLE IS RIGIDLY CONFINED LATERALLY BY THE BRASS RING. AXIAL LOADS ARE TRANSMITTED TO THE CONSOL 1 OOMETER DEAD LOAD- PHEUMAT 1 C ENDS OF THE SAMPLE BY POROUS DISKS. THE DISKS ALLOW DRAINAGE OF THE LOADED SAMPLE. THE AXIAL COMPRESSION OR EXPANSION OF THE SAMPLE IS MEASURED BY A MICROMETER DIAL INDICATOR AT APPROPRIATE TIME INTERVALS AFTER EACH LOAD INCREMENT IS APPLIED. EACH LOAD IS ORDINARILY TWICE THE PRECEDING LOAD. THE IN- CREMENTS ARE SELECTED TO OBTAIN CONSOLIDATION DATA REPRESENTING THE FIELD LOADING CONDITIONS FOR WHICH THE TEST IS BEING PERFORMED. EACH LOAD INCREMENT I5 ALLOWED TO ACT OVER AN INTERVAL OF TIME DEPENDENT ON THE TYPE AND EXTENT OF THE SOIL IN THE FIELD. METHOD OF PERFORMING CONSOLIDATION TESTS 01111181138 8 Neoogor PLATE A - 5