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HomeMy WebLinkAboutHARMONY MARKET PUD, 7TH FILING, GOLDEN CORRAL - PRELIMINARY & FINAL - 54-87Y - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTSUBSURFACE EXPLORATION REPORT PROPOSED GOLDEN CORRAL RESTAURANT HARMONY MARKET CENTER FORT COLLINS, COLORADO EEC PROJECT 1942044 EARTH ENGINEERING CONSULTANTS, INC. I I I J CI June 6, 1994 G C Development Corporation P.O. Box 29511 Raleigh, North Carolina 27626 Attn: Mr. Bill Kozar RE: Subsurface Exploration Report Proposed Golden Corral Restaurant Harmony Market Center Fort Collins, Colorado EEC Project No. 1942044 Mr. Kozar: FDT D, �,. EARTH ENGINEERING CONSULTANTS, INC. Enclosed, herewith, are the results of the subsurface exploration you requested for the referenced project. In summary, the subsurface soils encountered in the test borings completed as a part of this exploration consisted of low plasticity cohesive soils with varying amounts of sand and gravel. Based on the results of the field and laboratory testing it is our opinion these soils could be used for direct support of the proposed lightly loaded structure on conventional footing foundations. The near surface soils could also be used for direct support of floor slabs and pavements. Geotechnical recommendations concerning design and construction of the foundations and support of floor slab and pavements are presented in the text of the attached report. We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this 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. Principal Engineer cc: (5) Eldon Ward, Cityscape Urban Design Principal Engineer 2600 Canton Ct, Suite A Fort Collins, CO 80525 (303) 224-1522 FAX 224-4564 SUBSURFACE EXPLORATION REPORT PROPOSED GOLDEN CORRAL RESTAURANT HARMONY MARKET CENTER FORT COLLINS, COLORADO EEC PROJECT 1942044 INTRODUCTION The subsurface exploration for the proposed Golden Corral Restaurant to be constructed in the Harmony Market Center in Fort Collins, Colorado, has been completed. As requested three (3) soil borings extending to depths of approximately 15 feet below present site grades were advanced in the proposed building area and two additional borings were advanced to depths of approximately 5 feet in the proposed pavement areas. Individual boring logs and a diagram indicating the approximate boring locations are included with this report. We understand the proposed Golden Corral Restaurant will be constructed south of Harmony Road between Boardwalk and Lemay Avenues in Fort Collins, Colorado. The proposed restaurant will be a single story, slab on grade (non basement) structure with plan area of approximately 10,000 square feet. Foundation loads for the structure are expected to be light with continuous wall loads less than 3 kips per lineal foot and individual column loads less than 50 kips. Floor loads will be less than 100 psf. Paved drive and parking areas will be constructed along with to the new building. We expect those pavement areas will be used predominately by automobiles and light trucks. We anticipate less than 2 feet of cut and/or fill will be required to develop site grades for the restaurant. The purpose of this report is to describe the subsurface conditions encountered in the borings, analyze and evaluate the test data and provide geotechnical recommendations concerning design and construction of foundations and support of floor slabs and pavement. EXPLORATION AND TESTING PROCEDURES The boring locations were selected and established 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 locations of the borings should be considered accurate only to the degree implied by the methods used to make the field measurements. Earth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 2 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 continuous flight augers and samples of the subsurface materials encountered were obtained using thin -walled tube and split -barrel sampling procedures in general accordance with ASTM Specifications D-1587 and D-1586, respectively. In the thin -walled tube sampling procedure, a thin -walled, seamless steel tube with a sharpened cutting edge is pushed into the soil with hydraulic pressure to obtain a relatively undisturbed sample of cohesive or moderately cohesive material. In the split barrel sampling procedure, a standard 2-inch O.D. 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 -situ 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. Moisture content tests were completed on each of the recovered samples. In addition, dry density and unconfined strength tests were completed on appropriate samples. Swell/consolidation and Atterberg limits tests were also performed on selected samples to evaluate the potential for the site soils to change volume with variation with moisture content. Results of the outlined 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. SITE AND SUBSURFACE CONDITIONS The proposed Golden Corral Restaurant will be constructed south of Harmony Road, between Boardwalk and Lemay Avenues in Fort Collins, Colorado. The building site is located to the east of the Harmony Road entrance into the Harmony Market Center. Surface drainage at this �1 tEarth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 3 site is to the south with maximum difference in ground surface elevations across the building area on the order of 2 feet. The project site is covered with sparse grass and vegetation and evidence of prior building construction was not observed at the site by our drill crew. An EEC field geologist was on -site to direct the drilling activities and maintain a written log of the materials encountered in the boreholes. The field logs were prepared based on visual and tactual observation of disturbed samples and auger cuttings. Final boring logs included with this report may contain modifications to the field logs based on the results of laboratory testing and engineering evaluation. Based on results of the field borings and laboratory testing, subsurface conditions can be generalized as follows. Approximately three to six inches of vegetation and/or topsoil was encountered at the surface at the boring locations. The topsoil/vegetation was underlain by lean clay which contained varying amounts of sand and/or gravel. The coloration of the cohesive materials ranged from dark brown to reddish brown. The cohesive soils were generally stiff to very stiff near the surface and became softer with depth. Those materials extended to the bottom of the borings at depths ranging from approximately five feet for the borings in the pavement area to fifteen feet in the building area borings. The stratification boundaries shown on the boring logs represent the approximate locations of changes in soil types; in -situ, the transition of materials may be gradual and indistinct. IWATER LEVEL OBSERVATIONS Observations were made while drilling after completion of the borings to detect the presence and �- level of free water. Free water was observed in the building area borings at depths of approximately 14 feet as the boreholes were advanced. Approximately 24-hours after completion �- of the borings, freewater was observed in those open boreholes at depths of approximately 11.5 feet. Earth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 4 Longer term observations including the installation of piezometers which are sealed from the influence of surface water would be required to more accurately evaluate groundwater conditions. Zones of perched and/or trapped water may be encountered in more permeable zones in the cohesive materials. The location and amount of perched water and the depth to the hydrostatic groundwater table can vary over time depending on variations in hydrologic conditions and other conditions not apparent at the time of this report. ANALYSIS AND RECOMMENDATIONS FOUNDATIONS Based on the materials we observed at the test boring locations, it is our opinion the proposed lightly loaded building could be supported on conventional footing foundations. We recommend those foundations extend through all existing vegetation and/or topsoil and bear in the natural, stiff lean clay with varying amounts of sand and/or gravel materials. For design of the footing foundations bearing in natural, stiff to very stiff cohesive soils we recommend using a net allowable total load soil bearing pressure not to exceed 1,500 psf. The net bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure; total load includes 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. Trenched foundations (grade beam foundations) could be used in near surface cohesive materials. If used, we recommend those foundations have a width of at least 12-inches. No unusual problems are anticipated in completing the excavations required for the construction of footing foundations. Care should be taken during construction to minimize moisture variations of the bearing materials. Bearing materials which become dry and desiccated or wet Earth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 5 and softened should be removed prior to placement of reinforcement steel and foundation concrete. Disturbed materials should also be removed from beneath the footing foundations. We estimate the long term settlement of footing foundations designed and constructed as outlined above would be small, less than 3/4 inch. FLOOR SLAB AND PAVEMENT SUBGRADES All existing vegetation and/or topsoil should be removed from beneath floor slab and pavement areas. After stripping and completing all cuts and prior to placement of any fill, floor slabs or pavements, 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 material's maximum dry density as determined in accordance with ASTM Specification D-698, the standard Proctor procedure. The moisture content of cohesive soil subgrades should be adjusted to be within the range of -1 to +3 % of standard Proctor optimum moisture. Occasional zones of high silt content soils were encountered in the subgrade materials. High silt content soils are typically subject to strength loss and instability when wetted. It may be necessary to maintain the moisture content of high silt content soils at a lower level to increase the stability of these materials. Fill materials which are required to develop the floor slab and pavement subgrades should consist of approved, low volume change materials, free from organic matter and debris. Normally, cohesive soils with a liquid limit of 40 or less and plasticity index of 18 or less could be used for low volume change fill. If granular materials are used, we recommend those soils contain a minimum of 15 % fines, material passing a #200 sieve. The near surface cohesive soils encountered on the project site could be used for fill beneath the floor slabs or pavements. Fill materials beneath floor slabs or pavements should be placed in loose lifts not to exceed 9-inches thick, adjusted in moisture content as recommended for the scarified soils and compacted to at least 95 % of the material's standard Proctor maximum dry density. Earth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 6 Care should be taken after preparation of the subgrades to avoid disturbing the in -place materials. Care should also be taken to maintain the recommended moisture in the subgrades. If materials become dry and desiccated or wet and softened, it will be necessary to rework those materials prior to placement of the floor slabs or pavements. Disturbed materials will also need to be reworked prior to placement of the pavements or floor slabs. PAVEMENTS Based on previous work we have completed in this vicinity with similar soils, we estimate a Hveem stabilometer R-value of 7 would be appropriate for design of the pavement sections. We expect traffic on those pavements will consist of low volumes of automobiles and light trucks. We recommend pavements for the drive and parking areas consist of at least 3-inches of asphaltic concrete overlying by 6-inches of aggregate base. In automobile parking areas, a thinner pavement section consisting of 21h-inches of asphalt over 4-inches of aggregate base could be considered. The recommended pavement sections are minimums and, as such, periodic maintenance should be expected. We recommend asphaltic concrete for use in the pavement areas consist of SC-1 or SC-2 blends compatible with City of Fort Collins standard criteria. The aggregate base should be compatible with Colorado Department of Transportation (CDOT) requirements for Class 5 or Class 6 base. The base materials should be placed and compacted as recommended for fill beneath the pavements. Consideration could be given to stabilization of the pavement subgrades to develop a stronger pavement subgrade and reduce the required pavement sections. We recommend stabilization of the subgrades with Class C fly ash be considered. The Class C fly ash could be blended to a depth of 12-inches with the fly ash stabilized subgrade replacing the aggregate base course. We would be pleased to provide additional information concerning stabilization of the subgrades if desired. I IEarth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 7 OTHER CONSIDERATIONS Positive drainage should be developed away from the proposed building and across and away from the pavement edges. Water allowed to pond adjacent to the building could result in wetting of bearing soils and floor slab subgrades and result in unacceptable building performance. Water allowed to pond on or adjacent to the pavements could result in wetting of the pavement Isubgrades and premature failure of the pavement section. Care should be taken in completing on -site excavations to develop stable slopes of the sides of the excavations. We estimate slopes not steeper than 2 horizontal to 1 vertical would be relatively stable for short construction in shallow excavations. Longer term excavations or deeper excavations would require individual consideration. A portion of the near surface site soils have relatively high silt content. Those materials would be subject to instability and strength loss when wetted. It will be necessary to closely monitor the stability and moisture content of the site materials. Placement of high silt content soils at dryer moisture contents could result in higher stabilities. Stabilization of the pavement subgrades could also be considered to increase stability. Although the near surface soils at this site are not high plasticity materials, cohesive soils in general can experience volume change with fluctuation in moisture content. Large volume changes would not be expected in the site soils with normal moisture fluctuations. Some small ' movements may occur. IGENERAL 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 1 I Earth Engineering Consultants, Inc. Proposed Golden Corral Restaurant June 6, 1994 Page 8 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 Golden Corral Restaurant 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 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. HARMONY ROAD B-2 B-4 GOLDEN CORRAL B-3 Boring Location Diagram GOLDEN CORRAL RESTAURANT Fort Collins, Colorado Scale: None Drawn: SCK U. +h Ti ""I Onrinrt ('nnci�ltantc