The URL can be used to link to this page

Home My WebLink AboutAAMCO TRANSMISSION PUD, LOT 10, CREGER PLAZA 2ND REPLAT - PRELIMINARY / FINAL - 32-94 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTUNIFIED SOIL CLASSIFICATION SYSTEM Soil Classification Criteria for Assigning Group Symbols and Group Names Using Laboratory Testy Group Group Name a Symbol Coarse -Grained Soils more than Gravels more than 50% of coarse Clean Gravels Less than 5% finest Cu > 4 and 1 < Cc <3' GW Well -graded gravel' 50% retained on fraction retained on No. 200 sieve No. 4 sieve Cu < 4 and/or 1 > Cc > 3E GP Poorly graded gravel` Gravels with Fines more than 12% fines° fines classifyas ML or NIH GM Silty gravel,G,H Fines classify as CL or CH GC Clayey gravel`0" Sands 50% or more Clean Sands Less Cu > 6 and 1 < Cc < 3E SW Well -graded sand' of coarse fraction than 5% finese passes No. 4 sieve Cu < 6 and/or 1 > Cc > 3E SP Poorly graded sand' Sands with Fines Fines classify as ML or MH SM Silty sand°M•' more than 12% fines° Fines Classify as CL or CH SC Clayey sand"' Fine -Grained Soils Silts and Clays inorganic PI > 7 and plots on or above "A line' CL Lean clay".L." 50% or more Liquid limit less passes the than 50 PI < 4 or plots below "A" line' ML Silt".`" No. 200 sieve organic Liquid limit - oven dried Organic clay"La•v < 0.75 OL Liquid limit - not dried Organic silt"•� o Silts and Clays inorganic PI plots on or above "A" line CH Fat clay"-L'a Liquid limit 50 or more PI lots below "A" line MH Elastic Silt".L" organic Liquid limit - oven dried Organic clay'LL'a.P < 0.75 OH Liquid limit - not dried . Organic silt"'La'-° Highly organic soils Primarily organic matter, dark in color, and organic odor ABased on the material passing the 3-in. (75-mm) sieve _ .zCu=Daa/D,g Cc - fD101 'If field sample contained cobbles or D_0 x DGd boulders, or both, add "with cobbles or boulders, or both" to group name- cGravels with 5 to 12% fines require dual 'If soil contains > 15% sand, add "with symbols: sand" to group name. GW-GIM well -graded gravel with silt 'if fines classify as CL-ML, use dual symbol GW-GC well -graded gravel with clay GC -GM, or SC-SM. GP-GIM poorly graded gravel with silt "If fines are organic, add "with organic fines" GP -GC poorly graded gravel with clay to group name. °Sands with 5 to 12% fines require dual 'If soil contains > 15% gravel, add "with symbols: gravel" to group name. SW-SM well -graded sand with silt 'If Atterberg limits plot in shaded area, soil is SW -SC well -graded sand with clay a CL-ML, silty clay. SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay a 10 7 a ° PT Peat "If soil contains 15 to 29% plus No. 200, add "with sand" or "with gravel", whichever is predominant. Llf soil contains > 30% plus No. 200 predominantly sand, add "sandy" to group name. "If soil contains > 30% plus No. 200, predominantly gravel, add "gravelly" to group name. "PI > 4 and plots on or above "A" line. °PI < 4 or plots below "A" line. 'PI plots on or above "A" line. 'PI plots below "A" line. For classification of fine-grained soils and Iln►grained fraction of coarse- I /i grained soils Equation if 'A" - Tine I Hgn<ontal at Pt . a to LL " 255. men Pl " 0.73 ILL 20) ,J /' \IT,�Z11 j Eouanon of •U" - lino Vertical at LL " 16 To PI . 7, / man PI . 0.91Ll el G MHoftOHl �I r CL ML IMLoaOIL r I I I I 0 10 16 20 30 40 5o 60 70 6o 90 100 110 LIQUID LIMIT (LL) a ' f,--; elC a>�yf7 0 a -, C Y DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: SS : Split Spoon - 13." I.D., 2" O.D., unless otherwise noted PS : Piston Sample ST : Thin -Walled Tube - 2" O.D., unless otherwise noted WS : Wash Sample R : Ring Barrel Sampler - 2.42" I.D., 3" O.D. unless otherwise noted. PA : Power Auger FT : Fish Tail Bit HA : Hand Auger RB : Rock Bit DB : Diamond Bit = 4", N, B BS : Bulk Sample AS : Auger Sample PM : Pressure Meter HS : Hollow Stem Auger DC : Dutch Cone WB : Wash Bore Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2-inch O.D. split spoon, except where noted. WATER LEVEL MEASUREMENT SYMBOLS WL Water Level WS : While Sampling WCI : Wet Cave in WD : While Drilling DCI : Dry Cave in BCR : Before Casing Removal AS : After Boring ACR : After Casting Removal Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated levels may reflect the location of groundwater. In low permeability soils, the accurate determination of groundwater levels is not possible with only short term observations. DESCRIPTIVE SOIL CLASSIFICATION Soil Classification is based on the Unified Soil Classification system and the ASTM Designations D-2487 and 0-2488. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; they are described as: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are described as: clays, if they are plastic, and silts if they are slightly plastic or non -plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse grained soils are defined on the basis of their relative in -place density and fine grained soils on the basis of their consistency. Example: Lean clay with sand, trace gravel, stiff (CL); silty sand, trace gravel, medium dense ISM). CONSISTENCY OF FINE-GRAINED SOILS Unconfined Compressive Strength, Qu, psf Consistency < 500 Very Soft 500 - 1,000 Soft 1,001 - 2,000 Medium 2,001 - 4,000 Stiff 4,001 - 8,000 Very Stiff 8,001 - 16,000 Very Hard RELATIVE DENSITY OF COARSE -GRAINED SOILS: N-Blows/ft Relative Density 0-3 Very Loose 4-9 Loose 10-29 Medium Dense 30-49 Dense 50-80 Very Dense 80 + Extremely Dense PHYSICAL PROPERTIES OF BEDROCK DEGREE OF WEATHERING Slight Slight decomposition of parent material on joints. May be color change. Moderate Some decomposition and color change throughout. High Rock highly decomposed, may be extremely broken. HARDNESS AND DEGREE OF CEMENTATION: Limestone and Dolomite: Hard Difficult to scratch with knife. Moderately Can be scratched easily with knife, Hard Cannot be scratched with fingernail. Soft Can be scratched with fingernail. Shale, Siltstone and Claystone: Hard Can be scratched easily with knife, cannot be scratched with fingernail. Moderately Can be scratched with fingernail. Hard Soft Can be easily dented but not molded with fingers. Sandstone and Conglomerate: Well Capable of scratching a knife blade. Cemented Cemented Can be scratched with knife Poorly Can be broken apart easily with fingers Cemented AAMCO TRANSMISSION CENTER 3737 SOUTH MASON PROJECT NO: 1942035 FORT COLLINS, COLORADO DATE: MAY 1994 LOG OF TEST PIT TP-2 SHEET 1 of 1 RIG TYPE: CASE 550 #.<#s;:::>:;_.«>:}:z4{s„?:a..>•4.::.x;<.z.. ,,.,, . z«<x,>:.<:<' :,..1:::;.:<t,».>..:..s a::..:::.v;i<> kx;;s,.>lo.:::.<.,,:,,..:;: WATER DEPTH ELEV FOREMAN: RLD START DATE 4/28/94 WHILE DRILLING NONE AUGER TYPE: 4" CFA FINISH DATE 4/28/94 AFTER DRILLING NONE SPT HAMMER: MANUAL SURFACE ELEV 24 HOUR N/A SOIL DESCRIPTION D N QU MC DO a,-UMrrs -zoo SWELL LL PI PRESSURE %SOOPSF TYPE IFEEn (SLOWSIM RSF, 1%1 IPCFI l%i LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff, Fill LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff Calcareous deposits, Fill LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff, 5 (Possible Fill) LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff _ _ Calcareous De osits 10 15 20 25 "uE UE "E 47d1„�..,,..y ............_..._ AAMCO TRANSMISSION CENTER 3737 SOUTH MASON PROJECT NO: 1942035 FORT COLLINS, COLORADO DATE: MAY 1994 LOG OF TEST PIT TP-1 SHEET 1 OF 1 RIG TYPE: CASE 550 ,�;..:;eti::<::• ::>>.:..;,,..::.< nEx•):.:...: v.,;;;<zz:��::ax�::>'s«>>k�;>?;_>:`:.:a;s�pA!iy4.iS::C�vv,}3ti:s�n: START DATE 4/28/94 WATER WHILE DRILLING DEPTH NONE ELEV FOREMAN: RLD AUGER TYPE: 4" CFA FINISH DATE 4/28194 AFTER DRILLING NONE SPT HAMMER: MANUAL SURFACE ELEV 24 HOUR N/A SOIL DESCRIPTION D N QU MC DD A -LIMBS •200 SWELL LL PI PRESSURE %5W PSF TYPE IFEETI ISLOWSIFTI OsFI 1%I (PUF) 1%1 LIGHT BROWN SILTY LEAN CLAY (CL), _ moist, medium stiff Concrete & Asphalt Cobbles ,Fill _ LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff Calcareous Deposits, (Fill) 5 LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff Calcareous Deposits (Possible Fill) LIGHT BROWN SANDY LEAN CLAY (CL), moist, medium stiff _ _ Calcareous de osits 10 BOTTOM OF TEST PIT 7' 5". 15 20 25 art nnlneennn onsu tams AAMCO TRANSMISSION CENTER 3737 SOUTH MASON PROJECT NO: 1942035 FORT COLLINS, COLORADO DATE: APRIL 1994 LOG OF BORING B-2 SHEET 1 OF 1 RIG TYPE: DIETRICH D-50 <.:»...;i;ii`;a;;:F.v..;iu:>v".tkc:�c`:3^a<:`.".'ctcia'.iov <:>i>�:.�:�:,:;ia�:i::>.:.s��:�aEfi�:�;sz><:s;:;tx;.•izE.';;.:t»a<>.>.a�,s>. t\.2`:2$: WATER DEPTH ELEV FOREMAN: SCK START DATE 4/28/94 WHILE DRILLING 9 feet AUGER TYPE: 4" CFA FINISH DATE 4/28/94 AFTER DRILLING 9 feet SPT HAMMER: MANUAL SURFACE ELEV 24 HOUR N/A SOIL DESCRIPTION TYPE D (FEETI N I MLMS QU inn MC M DD (KF) A-UMITS -200 M SWELL LL % FH Wum %5M MF BROWN GRAVELLY SANDY CLAY (CL), moist, medium stiff, SS Fill SS SS _ 5 16 17.3 20 14.0 33 15 62.4 10 16 15.1 MOTTLED GRAY BROWN ORANGE SANDY CLAY (CL), moist, medium stiff SS (RESIDUAL) 21 20.9 SS ORANGE BROWN GRAY SANDSTONE slightly hard, plastic, highly weathered Grades to Brown SS 26 22.2 _ _ 15 25/2" 19.6 BOTTOM OF BORING 14' 2". 20 ac AAMCO TRANSMISSION CENTER 3737 SOUTH MASON PROJECT NO: 1942035 FORT COLLINS, COLORADO DATE: APRIL 1994 LOG OF BORING B-1 SHEET 1 OF 1 RIG TYPE: DIETRICH D-50 cK3f#g^€i i` >? < :t Xt'E�?: i `>.1:?? WATER DEPTH ELEV FOREMAN: SCK START DATE 4/28/94 WHILE DRILLING 10 feet AUGER TYPE: 4" CFA FINISH DATE 4/28/94 AFTER DRILLING 10 feet SPT HAMMER: MANUAL SURFACE ELEV 24 HOUR N/A SOIL DESCRIPTION TYPE D IFEETI N OLO SM) OU inn MC M DO jMF1 A -LINKS 200 1%1 SWELL LL N PMESSUPE %SOO PSF 6" TOP SOIL & VEGETATION BROWN SANDY CLAY (CL), moist, medium stiff SS Fill _ 5 14 13.5 37 16 71.4 <500 NONE LIGHT BROWN SANDY CLAY (CL), moist, medium stiff SS Fill 18 10.6 BROWN GRAVELLY SANDY CLAY (CL), moist, medium stiff SS Fill _ 10 18 15.0 MOTTLED ORANGE BROWN GRAVELLY SANDY CLAY (CL), moist, medium stiff RESIDUAL SS 11 25.9 SS ORANGE BROWN SANDSTONE slightly hard, plastic, highly weathered SS 16 28.0 _ _ 15 25/3" 20.1 BOTTOM OF BORING 14' 3". 20 25 6 -Z PRo�s� I�uswsraCi-�pA tt IO r7P- 1 Lo—r lz l r ; 0 d BORING LOCATION DIAGRAM LOT #10 - 3737 SOUTH MASON Ll 0 n C NOT TO SCALE FORT COLLINS, COLORADO APRIL 1994 Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 8 GENERAL COMMENTS The analysis and recommendations presented in this report are based upon the data obtained from the soil borings performed at the indicated locations and from any other information discussed in this report. This report does not reflect any variations which may occur between borings or across the site. The nature and extent of such variations may not become evident until construction. If variations appear evident, it will be necessary to re-evaluate the recommendations of this report. It is recommended that the geotechnical engineer be retained to review the plans and specifications so that comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. It is further recommended that the geotechnical engineer be retained for testing and observations during earthwork and foundation construction phases to help determine that the design requirements are fulfilled. This report has been prepared for the exclusive use of Cottier Construction 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. In the event that any changes in the nature, design or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the conclusions of this report modified or verified in writing by the geotechnical engineer. Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 7 Fill materials required to develop the floor slab or pavement subgrades should consist of approved, low volume change materials, free from organic matter and debris. Normally, soils with a liquid limit of 40 or less and plasticity index of 18 or less could be ,used as low volume change materials. Those soils should be placed in loose lifts not to exceed 9 inches thick, adjusted moisture content as recommended for the scarified soils and compacted to at least 95 % of the materials standard Proctor maximum dry density. After completion of the subgrades, care should be taken to avoid disturbing the in -place materials. Materials which are loosened or disturbed by the construction activities should be removed and replaced or, if possible, reworked in place prior to placement of floor slabs and pavements. OTHER CONSIDERATIONS Positive drainage should be developed away from the proposed building and across and away from the pavement edges. Water allowed to pond on or adjacent to the pavements could result in wetting of the pavement subgrades and premature failure of the pavement section. Water allowed to pond on or adjacent to the structure could result in wetting and softening of the bearing soils and excessive settlement of the building. Care should be taken in completing excavations required for installation of site utilities. Side slopes on the excavations should be developed to provide stable excavations. Based on the materials observed at the boring locations, we estimate slopes no steeper than 2 horizontal to 1 vertical would be relatively stable for short term construction activities in shallow excavations. Longer term excavations or deep excavations should be evaluated on an individual basis. Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 6 Care should be taken during construction to avoid disturbing the anticipated foundation bearing materials. Materials which are loosened or disturbed by the construction activities or materials which are dry and desiccated or wet and softened and should be removed from the foundation excavations prior to placement of the reinforcing steel and foundation concrete. Supporting the footing foundations on the in -place fill materials represents a risk of post - construction settlement caused by unacceptable materials which are not discovered during the building construction. With the close observation and testing recommended above and based on results of the test pit and field borings, we expect the risk of unacceptable performance to be small. We estimate the long term settlement of footing foundations designed and constructed as recommended above would be less than 3/4 inch. Design of a relatively stiff footing could help reduce the potential for differential settlement. FLOOR SLAB AND PAVEMENT SUBGRADE Based on the materials observed at the test pit and boring locations, we expect the floor slabs and pavements could also be supported on the in -place fill soils. The same cautions as enumerated for the footings regards to possible zones of loose or unacceptable materials would apply to the floor slab and pavement areas. To help locate any near surface soft and/or loose materials, we recommend the building and pavement areas be proofrolled with heavy construction equipment. Proofing should consist of several mutually perpendicular passes over the exposed subgrades using heavy construction equipment, such as a fully loaded tandem axle dump truck weighing not less than 40,000 pounds. Materials which appear to be loose or soft upon proofrolling should be removed or reworked in place prior to placement of additional fill, floor slabs or pavements. After proofrolling, we recommend the exposed subgrades be scarified to a minimum depth of 9 inches, adjusted in moisture content and compacted to at least 95% of the materials maximum dry density as determined in accordance with ASTM Specification D-698, the standard Proctor procedure. The moisture content of the cohesive site soils should generally be adjusted to be within the range of ±2% of standard Proctor optimum moisture. 's� Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 5 or construction of a post -tensioned slab -on -grade structure. We would be pleased to provide more detailed alternative recommendations at your request. FOOTING FOUNDATIONS Based on the materials observed at the test pit and boring locations, we expect that footing foundations could be supported on the in -place fill soils. As an alternative, the footings could be extended through the near surface fill soils to bear the natural, stiff to very stiff sandy clay. For design of footing foundation bearing on either the near surface fill materials or underlying cohesive soils, we recommend using a net allowable total load soil bearing pressure not to exceed 1500 psf. The net bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure. Total load implies full dead and live loads. Exterior foundations and foundations in unheated areas should be located a minimum of 30 inches below adjacent exterior grade to provide frost protection. We recommend formed continuous footings have a minimum width of 16 inches and isolated column foundations have a minimum width of 30 inches. Because of the need to closely observe and test the in -place bearing materials at the time of construction, we recommend trenched foundations (grade beam foundations) not be utilized. To further evaluate the foundation support soils, we recommend the anticipated bearing materials (both native and fill soils) be closely observed and tested at the time of construction. As a minimum, hand auger borings should .be completed at regular intervals along continuous footing lines and at each column location. Those hand auger borings should extend to a depth equal to at least one footing width below the anticipated bearing level. If objectionable materials are encountered, it may be necessary to extend the footings to bear below the objectionable material or those materials should be removed and replaced with properly placed and compacted fill. Recommendations can be provided at the time of construction if overexcavation and backfill procedures become necessary. Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 4 WATER LEVEL OBSERVATIONS Observations were made while drilling and after completion of the borings to detect the presence and level of free water. Water was observed at depths of approximately 9 to 10 feet in the two test borings. Based on those field observations, we expect the depth to the hydrostatic groundwater table was near that approximate depth at the time of drilling. Groundwater is commonly encountered as perched water above less permeable weathered bedrock. The location and amount of groundwater and/or perched water can vary over time depending on variations in hydrologic conditions and other conditions not apparent at the time of this report. ANALYSIS AND RECOMMENDATIONS GENERAL The near surface materials encountered at the project site consist of low plasticity cohesive fill soils which were reportedly placed without moisture and density control. Based on the testing and field observations completed as a part of this exploration, the fill soils appear to be relatively uniform and consistent without apparent voids or pockets of debris. Those materials also appear to be relatively compact. Recommendations are provided in this report for support of the structure using conventional footing foundations supported on the in -place fill materials. Placement of footings of the fill soils involves a risk of unacceptable performance subsequent to construction from undiscovered voids or deleterious materials within the fill remaining left in place beneath the structure. Close observation and testing during construction will reduce the risk of unacceptable post -construction performance. Alternate recommendations are also provided for support of the footing foundations on the in -place natural soils which were encountered beneath the fill materials. This procedure could be used to reduce the risk of settlement of the building structure although a risk would still remain in the floor slab and pavement areas. Recommendations for alternative preparation procedures can be provided if it is desired to further reduce or eliminate the risk of poor performance from the in -place fill materials. Those alternatives could include a deep foundation system, removal and replacement of all fill materials beneath the construction areas, Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 3 on visual and tactual observation of disturbed samples and auger cuttings. Coring and/or petrographic analysis may reveal other rock types. SITE AND SUBSURFACE CONDITIONS The AAMCO Transmission Center will be located at 3737 South Mason Street in Fort Collins, Colorado. Four to five feet of fill has reportedly been placed on the lot over the past 10 years. The fill was placed without moisture -density control and was reportedly placed in thin lifts over a period of time. Site drainage is presently slightly towards the west with maximum difference in ground surface elevations across the site on the order of 2 feet. An EEC field geologist was on site during excavation of the test pits and completion of the field borings. The EEC field geologist maintained a record of the materials encountered based on visual and tactual observation of disturbed samples and auger cuttings. Final boring logs included with this report may contain modifications to those field logs based on the results of laboratory testing and laboratory engineering evaluation. Based on results of the field borings and laboratory testing, subsurface conditions can be generalized as follows. Approximately 4 to 7 feet of fill material was encountered at the surface at the test locations. Those fill materials consisted of sandy clay with varying amounts of gravel. The fill material appeared to be relatively uniform and large voids or deposits of debris were not observed in the borings or test pits. The fill soils were underlain by brown and light brown sandy clay. The cohesive materials contained occasional calcareous deposits and varying deposits of gravel. Those soils extended to the bottom of the test pits, at depths of approximately 7 1/2 feet. The cohesive soils extended to depths of approximately 10 to 12 feet in the test borings. The cohesive soils were underlain by brown and gray highly weathered sandstone at those locations. The sandstone was poorly cemented and could be drilled using the standard auger drilling equipment. The stratification boundaries shown on the boring logs represent the approximate locations of changes in soil and rock types; in -situ, the transition materials may be gradual and indistinct. Earth Engineering Consultants, Inc. Proposed AAMCO Transmission Center Project No. 1942035 Page 2 locations should be considered accurate only to the degree implied by the methods used to make those field measurements. The borings were performed with a truck mounted, rotary type drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced using 4-inch nominal diameter continuous flight augers and samples of the subsurface materials encountered in the borings were obtained using split barrel sampling procedures. In the split barrel sampling procedure, a standard 2-inch OD split barrel sampling spoon is driven into the ground by means of a 140 pound hammer falling a distance of 30 inches. The number of blows required to advance the split barrel sampler is recorded and is used to estimate the in -site relative density of cohesionless soils and, to a lesser degree of accuracy, the consistency of cohesive materials. All samples obtained in the field were sealed and returned to the laboratory for further examination, classification and testing. Two test pits were excavated to depths of approximately 8 feet using a rubber tired backhoe. The test pit excavations were logged in the field by EEC personnel and disturbed samples of the materials encountered were obtained from the excavated materials. Those samples were also returned to laboratory for further examination, classification and testing. The laboratory testing for this project included moisture content tests on each of the recovered samples. In addition, a calibrated hand penetrometer was used to approximate the unconfined strength of selected samples. Atterberg limits and washed sieve analysis tests were also performed on selected samples. A swell consolidation test was performed on one selected sample to evaluate the potential for the site material to change volume with variation in moisture content. Results of the outline tests are shown on the attached boring logs. As a part of the testing program, all samples were examined in the laboratory by an engineer and classified in accordance with the attached General Notes and the Unified Soil Classification System, based on the soil's texture and plasticity. The estimated group symbol for the Unified Soil Classification System is shown on the boring logs and a brief description of that classification system is included with this report. The classification of the bedrock was based SUBSURFACE EXPLORATION REPORT PROPOSED AAMCO TRANSMISSION CENTER FORT COLLINS, COLORADO EEC Project No. 1942035 INTRODUCTION The subsurface exploration for the proposed AAMCO Transmission Center at 3737 South Mason in Fort Collins, Colorado has been completed. Two (2) soil borings extending to depths of approximately 15 feet below present site grades were advanced in the proposed building area to develop information on existing subsurface conditions. In addition, two (2) test pits were excavated to depths of approximately 8 feet to further evaluate the composition and consistency of the near surface fill soils. Individual boring/test pit logs and a diagram indicating the approximate test locations are included with this report. We understand the proposed AAMCO Transmission Center will be a single story, slab -on -grade masonry building. Foundation loads for this structure will be light with continuous wall loads less than 3 kips per lineal foot and column loads less than 30 kips. Grade changes of less than 2 feet are expected to develop the final site grades. Paved drive and parking areas will be constructed as a part of this development. We expect those pavements to be used predominantly by automobiles and light trucks and the traffic volume will be relatively light. The purpose of this report is the describe the subsurface conditions encountered in the borings, analyze and evaluate the test data and provide geotechnical recommendations concerning design and construction of the foundations and support of floor slabs and pavements. EXPLORATION AND TEST PROCEDURES The boring and test pit locations were selected in the field by Earth Engineering Consultants, Inc. (EEC) personnel. The field locations were determined by pacing and estimating angles from the references indicated on the attached boring location diagram. The boring/test pit i Earth Engineering Consultants, Inc. -Cottier Construction May 13, 1994 Page 2 We appreciate the opportunity to be of service to you on this project. If you have any questions concerning the enclosed report, or if we can be of further service to you in any other way, please do not hesitate to contact us. Very truly yours, Earth Engineering Consultants, Inc. Lester L. Litton, P.E. Colorado No. 23957 Reviewed by: Curtiss L. Palin, P.E. Colorado No. 27315 I DI EARTH ENGINEERING CONSULTANTS, INC. May 13, 1994 Cottier Construction P.O. Box 1051 Fort Collins, CO 80522 Attn: Mr. Pete Cottier RE: Subsurface Exploration Report Proposed AAMCO Transmission Center 3737 South Mason Fort Collins, Colorado EEC Project No. 1942035 Mr. Cottier: Enclosed with this letter are the results of the Subsurface Exploration you requested for the referenced project. In summary, the subsurface materials encountered in the test borings completed at this site consisted of low plasticity cohesive soils with occasional sand or gravel zones underlain by highly weathered sandstone bedrock. The top 4 to 7 feet of the overburden soils appeared to be fill material. Based on the results of our field and laboratory testing, it is our opinion the proposed lightly loaded structure could be supported on conventional footing foundations bearing directly on the in -place fill materials. Some risk would be involved in supporting footing foundations on the in -place fill soils which were reportedly placed without moisture or density control. However, with close observation and testing of those materials during construction, we expect the risk of unacceptable performance would be small. Alternate foundation types could be considered to reduce or eliminate the risk of settlement from the in -place fill soils. Geotechnical recommendations concerning design and construction of foundations and support of floor slabs and pavements are presented in the text of the attached report. 2600 Canton Ct, Suite A Fort Collins, CO 80525 (303) 224-1522 FAX 224-4564 SUBSURFACE EXPLORATION PROPOSED AAMCO TRANSMISSION CENTER FORT COLLINS, COLORADO EEC PROJECT 1942035 I P) EARTH ENGINEERING CONSULTANTS, INC.