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HomeMy WebLinkAboutLINCOLN EAST CONVENIENCE CENTER PUD (DIAMOND SHAMROCK) - PRELIMINARY - 40-94D - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGOODSON R ASSOCIATES 11949 West Colfax Avenue Denver, Colorado 80215 !'}fl7l 777_77dd TABLE I SUMMARY OF LABORATORY TEST RESULTS Project Number : 62555.01 Boring Depth Nat. Nat. Dry Atterberg. AASHTO Addi- No. Moist. Density Gravel Sand Fines Limits (Group SO4 Unified tional SOIL DESCRIPTION (feet) (i) (cf) (%) (% N LL I PI Index) N Class. Tests silty SAND R GPAVEL dditional Test Symbols: SW = Suell Consolidation, TX = Triaxial Compression, PT = Proctor Test UC = Unconfined Compression, GA = Gradation Analysis Page 1 of I CALIFORNIA BEARING RATIO N c* a Lo 0 0 0 0 0 1 N c7 Q U0 z w 2 w Q d ttf Q N X ii w 0 Q Z O i- U- J_ = m a < Q w U C7 > O ui w 2 0 O z z 0 Fo w 0 Fib :�L GOODSON & ASSOCIATES, INC. 4 3 c 2 �IIR�■11Moisture Content— 19.8 percent u oil �C fl �11 Expansion under constant load due to wetting. M�Ilflll �me�■�i�iii�iw 0. 1.0 10 100 APPLIED PRESSURE — ksf VA 1.0 - 10 100 APPLIED PRESSURE — ksf Project No. 62555.01 SWELL —CONSOLIDATION TEST RESULTS Fig. 6 No Text No Text I I LEGEND AND NOTES FOR BORING LOGS _ SAND, fine grained to coarse grained, gravelly, silty, some cobbles, loose to dense, slightly moist to wet, tan to brown ® _ CLAY, very stiff, moist, dark brown _ SAND, fine grained to coarse grained, slightly silty, medium dense to dense, Lj wet, tan to brown, mica, occasional gravel, occasional small cobbles ® _ CLAYSTONE, firm to medium hard, moist to very moist, gray e _ Drive Sample. Indicates 8 blows of a 140 pound hammer falling 30—inches were required to drive the 2—inch I.D. California sampler 12—inches. Drive Sample. Indicated 4 blows of a 140 pound hammer falling 30—inches 24/6 were required to drive the 2—inch O.D. split spoon sampler 6 inches and 26 blows were required for an additional 6—inches. - - Indicates groundwater was encountered while drilling. (1) Exploratory borings were drilled on July 14, 1994 with an 8—inch O.D. continuous. flight hollow stem power auger. (2) Locations of exploratory borings were measured approximately by pacing from features shown on the site plan provided. (3) Elevations of the exploratory borings were not measured and logs of exploratory borings are drawn to depth. (4) The exploratory boring locations should be considered accurate only to the degree implied by the method used. (5) The lines between materials shown on the exploratory boring logs represent the approximate boundaries between material types and the transitions may be gradual. (6) Groundwater levels shown on the logs were measured at the time and under conditions indicated. Fluctuations in the water level may occur with time. 0 0 OD30N a AMOCUM, INC. LEGEND AND NOTES ]]ws �'�' WedUI''""' ColfaxGNEIcoAvenue Lakewood. Colorado 80215 (303) 233-2244 Diamond Shamrock NEC of N. Lemay Avenue and E. Lincoln Avenue Fort Collins, Larimer County, Colorado Drawn By: MR Scale: Checked By: DAF Job No: 82555.01 Date: 07/20/94 Figure No: 3 W 5 20 25 BORING LOGS 1 2 3 0 :o :o G.. i% 6 0.. b 4/6 KNINM 21 N Am o W"D_ . ' 'O 22/6 NXINU o. 5 21/6 fl 17 a9 °0 10 4/6 36 15 W 24/6 6 Z 15 w 16 15 34 p 20 6 17/6 17/6 26/6 26/6 Diamond Shamrock NEC of N. Lemay Avenue and E. Lincoln Avenue Fort Collins, Larimer County, Colorado 25 Drawn By: MR Scale: 1" = 5' Checked By: DAF Job No: 62555.01 Date: 07/20/94 Figure No: 2 SITE PLAN Diamond Shamrock NEC of N. Lemay Avenue and E. Lincoln Avenue Fort Collins. Lorimer County. Colorado C00090N & A890CLATE9, INC. Consultlag Engineers ChE 11949 hest Colfax Avenue Lakewood. Colorado 60215 (303) 233-2244 Drawn By: MR Scale: NONE Checked By: DAF Job No: 82555.01 Date: 07/20/94 Figure No: 1 time of actual paving. In cut areas, the upper one foot of subgrade materials should also be compacted to that criteria. Concrete used for pavements should meet Colorado Department of Transportation specifications. We suggest the use of Class P concrete. The pavements are generally not designed to carry repeated heavy construction traffic. Therefore, construction operations subsequent to paving must be I planned so that traffic will avoid paved areas. Adequate drainage provisions should be made to prevent water flow into the subgrade soils beneath the pavements. The life of any pavement section is greatly diminished by improper drainage. MISCELLANEOUS In any foundation investigation it is necessary to assume that foundation conditions do not change greatly from those indicated by our exploratory borings. These borings are spaced in such a manner as to decrease the possibility of anomalies. However, our experience has shown that anomalies do sometimes become apparent during construction. For this reason, we recommend that a representative of our firm who is familiar with the surface conditions observe the construction discussed in this report. I 10 may require reworking or removal. Pockets of loose, soft or undesirable material should be replaced with properly compacted structural fill. Based on laboratory test results, the anticipated traffic, and our experience in the area, we recommend thaL/a�,Ove inch un inforced concrete pavement section be used for the site (see Figure 7). It is our understanding the owner wants to use a five inch reinforced pavement section, with #3 rebars running 18 inches on center each way. This will provide equal or greater strength and should perform satisfactorily. Prior to placement of the pavement sections, the entire area should be stripped l of all organic matter and debris. For regions of the site with clay materials as subgrade (A-7-6 or A-6 soils), the upper 12 inches of subgrade should be scarified, moisture conditioned to within -1 % to +3% of optimum moisture content and recompacted to a minimum of 95% of the maximum dry density (per ASTM D-698). The exposed surface of all areas to receive pavement should then be proofrolled with a heavy pneumatic -tired vehicle. Any soils which are noted to be pumping or deforming excessively under the moving wheel loads should be removed and replaced with a properly compacted and approved material. It is recommended that this operation be observed by a representative of our office. All fill placed in pavement areas should be compacted to at least 100 percent of the maximum standard Proctor density (per ASTM D-698) at, or near, the optimum moisture content. The subgrade should be adequately moist at the N BURIED TANKS Excavations for gasoline storage tanks will likely encounter groundwater. The i tanks should be anchored to compensate for buoyancy, as necessary. The excavation should be sloped ,adequately or stored to provide a safe working area. According to OSHA construction standards subpart P, the sand soils should be considered as "Type C". The excavation should be sloped according to these regulations at a maximum slope of 1-1/2:1 (horizontal to vertical) for 'Type C" soil to a maximum depth of 20 feet or until encountering groundwater. Groundwater was encountered at depths of 3 to 4% feet at the time of drilling; however, fluctuations may occur with time. We anticipate that dewatering the tank excavations will be necessary for construction. CEMENT As a precautionary measure, we recommend the use of Type II cement in all concrete exposed earth at the site. PAVEMENT DESIGN The predominant subgrade materials at the site consist of silty, gravelly sands and clays. These materials classify as A-1-b, A-3, and A-7-6 in the American I Association of State Highway and Transportation Officials (AASHTO) Classification with group index values ranging form 0 to 32. These soils would typically be poor to excellent subgrade materials. The minimum expected R- Value of the site materials would be on the order of 5. Some of the sand soils FLOOR SLAB CONSTRUCTION The natural soils and/or properly compacted fill materials are suitable to support interior floor slabs. However, as described in the previous section of this report the expansive clays beneath, the floor slab regions should be removed and replaced with properly compacted structural fill. This will require careful inspection during construction and may include 3 feet of removal and replacement. In order to help prevent capillary water rise, a minimum of 4 inches of clean gravel should be placed beneath the slabs. All loose material or new fill beneath the slabs should be moistened and compacted to at least 95 percent of standard Proctor density (per ASTM D-698). SURFACE GRADING Precautions should be taken against wetting or drying of the foundation soils after construction. Backfill around the building should be moistened and well compacted. Exterior surface drainage must not be allowed to collect at or near the building. The exterior grade should be sloped well away from the structure. A minimum slope of 6 inches in the first 10 feet away from the foundation walls is lrecommended in landscaped areas. A minimum slope of 3 inches for the first i 10 feet is acceptable in paved areas. 7 Interior loads should be supported on beams and columns, placed on isolated pads, designed as above. Wall footings should be at least 12 inches in width and column footings should be at least 18 inches wide for bearing capacity consideration. Structural fill should consist of non -swelling soils such as silty sands and should be compacted to at least 1 DO percent of the maximum standard Proctor density (per ASTM D-698) at or near the optimum moisture content. The design and construction criteria presented below should be observed for a spread footing foundation system. The construction details should be considered when preparing the project documents. l 1) Foundation walls should be well reinforced, both top and bottom. This is to give them sufficient beam strength to span isolated loose or expansive pockets which may occur in the bearing strata below foundation levels. i 2) The soils exposed in the bottoms of the footing excavations must be inspected by a representative of our firm. The clay soils should be i completely removed and some of the silty sand soils may require reworking or removal prior to placing footings. Pockets of loose, soft or undesirable material should be replaced with properly compacted structural fill approved by the soil engineer, preferably a silty sand. L FOUNDATION RECOMMENDATIONS i As shown by our swell -consolidation test, Figure 6, the clay soils encountered i in Boring 3, at this site possess a moderate swell potential. Shallow foundations placed on these soils could experience movement causing structural distress if the soil is subject to changes in moisture content. However, as shown in our boring logs, Figure 2, the majority of the near surface soils consists of silty, gravelly sand. The potentially expansive clay soils in Boring 3 were only present to a depth of three feet. .Provided an inspection of the footing excavations confirms the clay soils have been removed, we recommend that the structures be placed on footings bearing below frost depth (at least 30 inches) on the natural soils and/or properly compacted structural fill. Any potentially expansive clay soils that are observed in the footing excavations should be removed and replaced with properly compacted structural fill. The owner has proposed a wall -on -grade foundation system extending below frost depth, poured monolithically with the floor slab. In our opinion this design will perform adequately at the site and have similar risk of movements as footings. The term "footings" in this report should also include this wall -on -grade foundation type. i Spread footings should be designed for a maximum allowable soil bearing l pressure of 2,000 psf if placed directly on natural soils or properly compacted structural fill. A uniform dead -load design should be used to help prevent differential movements. 5 SITE CONDITIONS Surface: The project site is presently in use as a residence with a horse grazing area. A two story frame building is located at the approximate center of the site. The ground surface, is relatively flat. The site is bare of vegetation except for the area surrounding the existing building, which is lightly vegetated with grasses. The site is bounded by East Lincoln Avenue to the south and North Lemay Avenue to the west. Vacant lots were located to the north and east. Subsurface: The subsurface conditions at the site were somewhat variable. At the ground surface in Borings 1 and 2 and at a depth of 3 feet in Boring 3 a gravelly, silty sand was encountered. This gravelly, silty sand was fine to coarse grained, loose to dense, slightly moist to wet and tan to brown. Boring 3 encountered a very stiff clay at the ground surface which was moist and dark brown in color. At depths of 4 to 12 feet in all three borings a slightly silty sand was encountered which extended to depths ranging from 16% to 19 feet. This I) sand was fine to coarse grained, medium dense to dense, wet and tan to brown in color. Beneath the slightly silty sand in Borings 1 and 2 a firm to medium hard clystone was encountered which extended to a maximum depth explored of 21 % feet. This claystone was moist to very moist and gray. Groundwater was encountered in Borings 1 and 2 at depths of 4% and 3 feet respectively at the time of drilling. A graphical presentation of the subsurface soil and bedrock conditions encountered in the borings is presented in the Boring Logs, Legend and Notes, Figures 2 and 3. At regular intervals soil samples were obtained with a 2-inch I.D. California Barrel Sampler. The sampler was driven into the various subsoil strata with blows of a 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler one foot, or a fraction thereof, constitutes the i penetration test. This field test is similar to the standard penetration test described by ASTM Method D-1586. Penetration resistance values, when properly evaluated, are an index to the soil strength and density. The depths at which the samples were taken and the penetration resistance values are shown _f on the Boring Logs, Figure 2. A weighted type measure was used to determine the groundwater level, if present, in the borings. LABORATORY TESTING All samples were carefully inspected and classified in the laboratory by the Project Engineer. Natural moisture contents, dry unit weights, both full and partical gradation analyses, and Atterberg Limits were performed on samples selected from relatively undisturbed drive samples of typical materials encountered. In addition, a swell -consolidation test was performed on a typical sample of potentially swelling materials (see Figures 4 through 6 and Table 1). PROPOSED CONSTRUCTION As we understand, the proposed construction will be a convenience store, gasoline pumps and canopy, buried tanks, car wash and associated facilities. No basement areas are planned. Foundation loads are expected to be light. 3 SCOPE OF STUDY This report presents the results of a geotechnical engineering study at the site of the proposed. Diamond Shamrock Convenience Store and Service Station to be located at the northeast corner of North Lemay Avenue and East Lincoln Avenue, Fort Collins, Larimer County, Colorado. The purpose of this study was to explore the subsurface conditions, obtain some 1 data of the pertinent characteristics of the underlying strata, recommend the most appropriate foundation system, develop specific foundation design criteria, and attempt to evaluate the risks of slab -on -grade construction. It should be understood that economic and practical constraints limit our sampling and laboratory testing to only a minuscule fraction of the total mass of soil and/or bedrock which lies within the zone of influence of the proposed construction. Our analyses, conclusions and recommendations are based upon the assumption that the samples of subsurface strata, which we observed and tested, are representative of the entire soil mass. FIELD INVESTIGATION Three (3) exploratory test borings were drilled at the site, at the locations shown on Figure 1. The borings were drilled with an 8-inch O.D., continuous flight, hollow stem power augers using a truck -mounted drill rig. I 2 SUMMARY 1) The subgrade conditions at the site are somewhat variable. Our borings encountered 0 to 3 feet of stiff clays avove silty, gravelly sands. At depths of 4 to 12 feet a slightly silty sand was encountered which extended to depths of 16% to 19 feet. Claystone bedrock was i encountered in Borings 1 and 2 at depths of 18 to 19% feet and extended to a maximum depth explored of 21 % feet. Groundwater was encountered in Borings 1 and 2 at depths of 4 and 3% feet respectively at the time of drilling. 2) In our opinion, the structure should be founded on footings placed below frost depth (30 inches) on the natural soil materials and/or properly compacted structural fill. The footings would be designed using a maximum allowable soil bearing pressure of 2,000 psf. 3) Floor slabs may be supported on -grade as discussed in the text of this report. 4) Concrete pavement designs are provided in the text of this report. 5) A representative of our firm should observe the construction operations discussed in this report. 1 TABLE OF CONTENTS I i Page ' Summary ............................................. 1 Scope of Study ......... 2 Field Investigation ....................................... 2 Laboratory Testing ...................................... 3 1 Proposed Construction .................................... 3 Site Conditions ......................................... 4 Foundation Recommendations ............................. 5 Floor Slab Construction ................................... .7 Surface Grading ........................................ 7 Buried Tanks .......................................... 7 Cement.............................................. 8 Pavement Design ....................................... 8 Miscellaneous ......................................... 10 LIST OF TABLES AND FIGURES Figure 1 - Boring Hole Locations Figure 2 - Boring Logs Figure 3 - Legend and Notes for Boring Logs Figures 4 and 5 - Gradation Curve Figure 6 - Swell -Consolidation Result Figure 7 - Design Nomograph for Rigid Pavement Table 1 - Summary of Laboratory Test Results GEOTECHNICAL ENGINEERING STUDY DIAMOND SHAMROCK CONVENIENCE STORE AND SERVICE STATION NORTHEAST CORNER OF NORTH LEMAY AVENUE AND EAST LINCOLN AVENUE FORT COLLINS, LARIMER COUNTY, COLORADO u Prepared for DIAMOND SHAMROCK 520 East 56th Avenue Denver, Colorado 80216 By GOODSON & ASSOCIATES, INC. 11949 West Colfax Avenue Lakewood, Colorado 80215 (62555.01) Prepared by%��� ? Michelle Akichards, E.I.T. r• Reviewed b David A. Field, P.E.V _ .1m i Date 1z t Z0g41 GZ Goodson & Associates, Inc. C6nsulting Engineers GEOTECHNICAL ENGINEERING STUDY DIAM(;ND SHAMROCK CONVENIENCE Al v STORE AND SERVICE STATION /7 : A .... , . �._NORTHCORNER OF 'NORTH LEMA' Y:., IT . AVENUE 'AND EAST LINCOLN AVENUE . � FORVZOLUNS LARIMtR. COUNTY DIL L] COLORADO;. -j 1.'.. lA AUGUST 109 1994 r '"I (62565.01)