Loading...
HomeMy WebLinkAboutKING SOOPERS #146 MIDTOWN GARDENS MARKETPLACE - PDP200012 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT800 Stockton Avenue; #4 Fort Collins, CO 80524 phone: (970) 416-9045 fax: (303) 742-9666 email: kaftcollins@kumarusa.com www.kumarusa.com Office Locations: Denver (HQ), Colorado Springs, Fort Collins, Glenwood Springs, Parker, and Frisco/Silverthorne, Colorado GEOTECHNICAL ENGINEERING STUDY AND PAVEMENT THICKNESS DESIGN PROPOSED KING SOOPERS #146 SHOPPING CENTER NORTHWEST CORNER OF SOUTH COLLEGE AVENUE AND WEST DRAKE ROAD FORT COLLINS, COLORADO DRAFT Prepared By: Reviewed By: David Castelbaum, P.E . James A. Noll, P.E. Prepared For: King Soopers Facility Engineering Department 65 Tejon Street Denver, Colorado 80223 ATTENTION: Mr. Kevin McKenzie Project No. 16-3-183 November 23, 2016 Kumar & Associates, Inc TABLE OF CONTENTS SUMMARY .......................................................................................................................................... 1 PURPOSE AND SCOPE OF WORK .................................................................................................. 3 PROPOSED CONSTRUCTION .......................................................................................................... 3 SITE CONDITIONS ............................................................................................................................. 4 SUBSURFACE CONDITIONS ............................................................................................................ 4 LABORATORY TESTING ................................................................................................................... 5 GEOTECHNICAL CONSIDERATIONS ............................................................................................... 6 SEISMIC DESIGN CRITERIA ............................................................................................................. 7 FOUNDATION RECOMMENDATIONS .............................................................................................. 7 FLOOR SLABS AND EXTERIOR FLATWORK ................................................................................... 9 SITE GRADING ................................................................................................................................ 10 FOUNDATION WALLS AND RETAINING STRUCTURES ............................................................... 14 WATER SOLUBLE SULFATES ........................................................................................................ 14 SURFACE DRAINAGE ..................................................................................................................... 15 PAVEMENT THICKNESS DESIGN .................................................................................................. 16 DESIGN AND CONSTRUCTION SUPPORT SERVICES ................................................................. 19 LIMITATIONS .................................................................................................................................... 19 FIG. 1 – LOCATION OF EXPLORATORY BORINGS FIGS. 2 through 5 – LOGS OF EXPLORATORY BORINGS, LEGEND AND NOTES FIGS. 6 through 13 – SWELL/CONSOLIDATION TEST RESULTS FIGS. 14 through 15 – GRADATION TEST RESULTS TABLE I - SUMMARY OF LABORATORY TEST RESULTS Kumar & Associates, Inc SUMMARY 1. The subsurface conditions at the site were evaluated by drilling 20 exploratory borings to depths ranging from about 15 to 50 feet below existing ground surface. Asphalt pavement was encountered at the surface of all borings and varied from approximately 2¼to 9½ inches in thickness with an average thickness of about 4½ inches. Three (3) of the borings encountered aggregate base course beneath the asphalt with thicknesses ranging from about 4½ o 6 inches. Fill materials ranging from approximately 1 to 6 feet thick were encountered beneath the pavement in all of the borings and consist of slightly moist to moist lean to sandy lean clays, occasionally with gravel. The fill is underlain by natural overburden soils underlain in turn by sandstone and claystone bedrock. The natural overburden soils encountered beneath the fill extend to depths of approximately 32 to 38 feet in eight (8) borings and to the maximum depth drilled in all of the remaining borings. The natural soils consist predominantly of lean to sandy lean clay interlayered with poorly-graded to silty-clayey sands. The sandy clay soils are generally soft to stiff and occasionally very stiff, and the interlayered granular soils are generally loose to dense based on field penetration resistance tests. Bedrock was encountered in these same eight (8) borings beneath the overburden soils and extended to the maximum depths drilled of approximately 40 to 50 feet. Sandstone bedrock was encountered in all eight (8) of these borings and is weakly cemented, fine to coarse-grained, silty, moist to wet, and varies from tan, gray to yellowish-gray, and brown to grayish-brown in color. Claystone bedrock was encountered in one (1) boring below the sandstone at a depth of approximately 33 feet and is sandy, moist, and grayish-brown. Based on field penetration resistance test, the sandstone and claystone are hard to very hard. 2. Groundwater was encountered in 12 of the borings at the time of drilling at depths ranging from about 12 to 18 feet. Groundwater levels were approximately 12 to 14½ feet when measured between 14 and 21 days after drilling. Groundwater is not expected to affect the proposed construction. However, groundwater levels are expected to fluctuate with season, and may rise after wet weather or subsequent to landscape irrigation. Also, development of perched groundwater on top of or within layers of the fine-grained (i.e., clays) overburden soils may occur, particularly after wet weather and landscape irrigation subsequent to development. 3. We believe that shallow spread footings are a suitable foundation system for the proposed buildings described in this report. Footings should be placed on the undisturbed natural sandy clay soils or properly compacted structural fill. Spread footings should be designed for a net allowable bearing pressure of 2,500 psf. 4. The exploratory borings indicate existing fill at or near anticipated foundation bearing elevations. These fill materials are not considered suitable for support of foundations, unless documentation can be provided indicating otherwise, and should be removed. The footings be should be extended through the fill to the underlying undisturbed natural soils. Kumar & Associates, Inc Alternatively, the existing fill materials may be replaced by properly compacted structural fill that extends to the natural soils. 5. Slab-on-grade construction is also feasible at this site. We recommend all fill material under slabs be removed and replaced with properly compacted structural fill. If the owner is willing to accept the risk of potential movement, slabs may be placed on at least 3 feet of properly compacted structural fill material. 6. Flexible and rigid pavement sections are shown in the table below. Additional pavement design and construction criteria are presented in the body of this report. LOCATION* Pavement Section Thicknesses (inches) Full-Depth Hot Mix Asphalt Hot Mix Asphalt over Aggregate Base Course Portland Cement Concrete Light Duty 7 4½ over 9 6 Heavy Duty 8½ 5½ over 10 7 *Light Duty: Automobile parking; Heavy Duty: Access drives, fire lanes. 3 Kumar & Associates, Inc PURPOSE AND SCOPE OF WORK This report presents the results of a geotechnical engineering study for the King Soopers Store #146 and retail development to be located on the northwest corner of South College Avenue and West Drake Road in Fort Collins, Colorado as shown on Fig. 1. The study was conducted in accordance with the scope of work in our Proposal No. P3-16-253 dated October 21, 2016. A field exploration program consisting of exploratory borings was conducted to obtain information on subsurface conditions. Samples of soils and bedrock obtained during the field exploration were tested in the laboratory to determine their strength, compressibility or swell characteristics, and classification. Results of the field exploration and laboratory testing were analyzed to develop recommendations for the building foundations and floor slabs, exterior flatwork areas, and pavements. The results of the field exploration and laboratory testing are presented herein. This report has been prepared to summarize the data obtained during this study and to present our conclusions and recommendations based on the proposed construction and the subsurface conditions encountered. Design parameters and a discussion of geotechnical engineering considerations related to construction of the proposed facility are included in the report. PROPOSED CONSTRUCTION The project will consist of re-developing an existing approximate 12.6-acre retail center currently occupied by a large retail/outlet type store and two smaller structures. The large retail building and one of the smaller structures will be demolished as part of the proposed construction. The proposed construction will consist of a King Soopers store having a footprint of approximately 123,000 square feet, a detached retail building of approximately 8,500 square feet and associated asphalt paved driveways and parking areas. The proposed store will be a tall, single-story structure with slab-on- grade floors typical of other King Soopers stores completed locally. A drive through pharmacy lane will be constructed on the north side of the proposed building. The detached retail building will be located in the northeast corner of the site. The design team is considering reuse of the existing asphalt paved driveways and parking areas. Part of this study will include a limited visual assessment of the existing pavement and our opinion regarding the relative condition and structural support characteristics of the existing pavement section. If the proposed construction varies significantly from that generally described above or depicted in this report, we should be notified to reevaluate the conclusions and recommendations provided herein. 4 Kumar & Associates, Inc SITE CONDITIONS The project site is an approximate 12.6-acre rectangular property on the northwest corner of South College Avenue and West Drake Road. The property is bordered by the City of Fort Collins Max BRT Mason Corridor to the west and by an existing retail center to the north. The existing large retail building occupies the northwest portion of the property and has a footprint approximately the same as the proposed King Soopers building. Two (2) smaller retail buildings are located in the north and southeast corners of the property. The large building and small northeast retail building will be demolished to make way for the proposed construction. A limited visual assessment of the existing asphalt paved driveways and parking areas was included in this study. The majority of the pavement at the site is in fair to poor condition having elevated levels of distress, as well evidence of prior crack sealing and patching throughout the paved areas. Distresses noted include longitudinal and transverse cracking with crack widths measuring approximately ¼ to 1½ inches and depths greater than approximately 1 to 1½ inches, alligator and block cracking, potholes, some rutting and areas of pavement settlement/subsidence resulting in ponding and standing water. These distresses are also observed within areas of prior patching and crack sealing. The distresses are predominantly moderate in severity, followed by high and low severity in order of decreasing area affected. Asphalt pavement was encountered at the surface of all of the borings and varied from approximately 2¼ to 9½ inches in thickness with an average thickness of about 4½ inches. Three of the borings encountered aggregate base course beneath the asphalt with thickness ranging from about 4½ to 6 inches. SUBSURFACE CONDITIONS The subsurface conditions at the site were investigated by drilling 20 exploratory borings to depths ranging from about 5 to 50 feet below the existing ground surface. Ten (10) borings were drilled to depths ranging from about 20 to 50 feet around the perimeter of the existing large retail building where the proposed King Soopers store will be located. Ten (10) borings were drilled in the existing paved driveways and parking areas to approximately 15 feet. The approximate locations of the borings are shown on Fig. 1. The logs of the exploratory borings are presented on Figs. 2 through 4, and the associated legend explanatory notes are also presented on Fig. 5. Subsurface Soil and Bedrock Conditions: Asphalt pavement was encountered at the surface of all of the borings and varied from approximately 2¼ to 9½ inches in thickness with an average thickness of about 4½ inches. Three (3) of the borings encountered aggregate base course beneath the asphalt with thickness ranging from about 4½ to 6 inches. Fill materials of variable thicknesses ranging from approximately 1 to 6 feet thick were encountered beneath the pavement in all of the borings and consists of lean to sandy lean clays, occasionally with gravel that are slightly moist to 5 Kumar & Associates, Inc moist. The fill is underlain by natural overburden soils underlain in turn by sandstone and claystone bedrock. The natural overburden soils encountered beneath the fill extend to depths of approximately 32 to 38 feet in eight (8) borings and to the maximum depth drilled in all of the remaining borings. The natural soils consist predominantly of lean to sandy lean clay occasionally grading to clayey sand interlayered with poorly-graded to silty-clayey sands. The sandy clay soils are generally soft to stiff and occasionally very stiff, and the interlayered granular soils are generally loose to dense based on field penetration resistance tests. Bedrock was encountered in these same eight (8) borings beneath the overburden soils at depths of 32 to 38 feet and extended to the maximum depths drilled of approximately 40 to 50 feet. Sandstone bedrock was encountered all eight of these same borings and is weakly cemented, fine to coarse-grained, silty, moist to wet, and varies from tan, gray to yellowish-gray, and brown to grayish-brown in color. Claystone bedrock was encountered in one (1) boring beneath the sandstone at a depth of approximately 33 feet and is sandy, moist, and grayish-brown. Based on field penetration resistance test, the sandstone and claystone are hard to very hard. Groundwater Conditions: Groundwater was encountered in 12 of the borings at the time of drilling at depths ranging from about 12 to 18 feet. Groundwater levels were approximately 12 to 14½ feet when measured between 14 and 21 days after drilling. Groundwater is not expected to affect the proposed construction. However, groundwater levels are expected to fluctuate with season, and may rise after wet weather or subsequent to landscape irrigation. Also, development of perched groundwater on top of or within layers of the fine-grained (i.e., clays) overburden soils may occur, particularly after wet weather and landscape irrigation subsequent to development. LABORATORY TESTING Laboratory testing was performed on selected soil and bedrock samples obtained from the borings to determine in-situ soil moisture content and dry density, Atterberg Limits, swell-consolidation characteristics, gradation characteristics, and water soluble sulfates. The results of the laboratory tests are shown to the right of the logs on Figs. 2 through 6 and summarized in Table 1. The results of specific tests are graphically plotted on Figs. 7 through 13. The testing was conducted in general accordance with recognized test procedures, primarily those of the American Society for Testing of Materials (ASTM). Swell-Consolidation: Swell-consolidation tests were conducted on samples of the existing fill and natural overburden soils. The tests were performed in order to determine the compressibility and swell characteristics of the samples under loading and when submerged in water. Samples are 6 Kumar & Associates, Inc subjected to a surcharge pressure of 200 or 1,000 psf, and allowed to consolidate before being submerged. Results of the swell-consolidation tests are presented on Figs. 7 through 13. The results of the swell-consolidation tests indicate that the existing fill and natural overburden soils generally have low compressibility to moderate swell upon wetting at surcharge pressures of both 200 and 1,000 psf. Samples of the fill and natural overburden soils exhibited compression of -0.1% to low swell of 1.3% when wetted under a 200 psf surcharge pressure, and low compressibility of -1.8% to moderate swell of 2.4% under a 1,000 psf surcharge pressure. Swell pressures ranged from approximately 1,000 to 6,000 psf. Index Properties: Laboratory testing was performed to determine the index properties of the soils found at the site including: liquid limit and plasticity index, and particle-size distribution (gradation). The index properties were used to classify the soils into categories of similar engineering properties according to the American Association of Highway Transportation Officials (AASHTO) system and the Unified Soil Classification System (USCS) (ASTM D 2487). The classification of the soils present at this site are presented in Table I and indicated on the boring logs. GEOTECHNICAL CONSIDERATIONS As previously discussed, subsurface conditions generally consist of variable depths of fill overlying natural overburden soils. Unless documentation can be provided indicating otherwise, the existing fill materials are not considered suitable for support of foundations or floor slabs and should be removed. Based upon the field data and laboratory testing, the exiting fill materials have variable moisture content and density/unit weight. The soils encountered at the site conditions are commonly associated with increased swell potential when they are at lower moisture content and higher density conditions which can result in heaving movements of structures or slabs placed on these types of materials. Conversely, higher moisture content and lower density conditions are associated with compression/consolidation resulting in settlement and potential damage to foundations and floor slabs. With proper site preparation, shallow spread footing foundations and building slab-on-grade construction should be feasible. Proper site preparation should include complete removal of existing fills within the proposed building footprint and beneath other settlement sensitive structures down to the natural soils and replacement with compacted structural fill. The provision of a minimum thickness of structural fill would result in more uniform bearing conditions beneath footings and floor slab support, and in more predictable foundation settlement. To reduce the effects of potential differential movements of the fill materials, and possible damage as a result, we recommend that all existing fill beneath slab-on-grade floors, exterior flatwork and 7 Kumar & Associates, Inc pavements be removed and replaced with structural fill. The magnitude of potential movement across the site post-construction if the fill is left in-place cannot be accurately predicted. However, total and differential movements on the order of 1 to 2 inches could occur. If the owner is willing to accept the risk of potential movement(s) in excess of normal tolerances, floor slabs and exterior flatwork adjacent to the buildings should be placed on at least 3 feet of properly compacted structural fill. The owner should be aware that the reduced thickness of fill removal will not eliminate the risk of movements; however, the total magnitude(s) should be reduced. SEISMIC DESIGN CRITERIA The Colorado Front Range is located in a low seismic activity area. The soil profile consists generally of comparatively medium dense granular and medium to stiff clay overburden soils overlying hard to very hard bedrock. The overburden materials will generally classify as International Building Code (IBC) Site Class D. The underlying bedrock generally classifies as IBC Site Class C. Based on our experience with similar subsurface profiles in the area, we recommend a design soil profile of IBC Site Class D. Based on the subsurface profile, and site seismicity, liquefaction is not a design consideration. FOUNDATION RECOMMENDATIONS Spread Footings: Based on the surface conditions encountered in the exploratory borings, the results of laboratory testing, and previous experience, we recommend the King Soopers store and the detached retail building be founded on shallow spread footings placed on the undisturbed natural soils or properly compacted structural fill extending to the natural soils. The design and construction criteria presented below should be observed for a spread footing foundation system. The construction details should be considered when preparing project documents. 1. Footings should be placed on the undisturbed natural soils or properly compacted structural fill extending to the natural soils. The footings should be designed for a net allowable soil bearing pressure of 2,500 psf. 2. Areas of loose and/or soft soils, or other deleterious materials encountered within footing excavations should be removed and the footings extended down to underlying undisturbed natural soils or replaced with structural fill meeting the material and placement criteria provided in the “SITE GRADING” section of this report. All foundation elements, floor slabs, and other debris resulting from demolition of structures should be removed from within the new building footprints. Any irregular or otherwise 8 Kumar & Associates, Inc unsuitable foundation excavations should be backfilled with structural fill as described in the “SITE GRADING” section of this report. Special compaction procedures including hand compaction methods may be required in tight confined excavation areas in order to meet the compaction requirements. 3. The results of our field exploration indicate existing fill at or below anticipated foundation bearing elevations. The existing fill materials are not considered suitable for support of foundations and should be removed. The footings should be extended through the fill to the underlying undisturbed natural soils. Alternatively, the existing fill materials can be replaced by properly compacted structural fill that extends to the natural soils. Structural fill should meet the material and placement criteria provided in the “SITE GRADING” section of this report. New fill should extend down from the edges of the footings at a 1H:1V (horizontal-to-vertical) projection. 4. Spread footings should have a minimum footing width of 16 inches for continuous footings and 24 inches for isolated pads. 5. A minimum 4-inch void should be provided beneath grade beams between pads 6. Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 30 inches below the exterior grade is typically used in this area. Resistance to lateral sliding can be determined using working values of 0.3 for a coefficient of friction along the bottom of the footings and 185 for an equivalent fluid weight for passive pressure against the sides the footings. Compacted fill placed against the sides of the footings to resist lateral loads should be non- expansive materials. Fill should meet the material requirements and be moisture conditioned and compacted as indicated in the “SITE GRADING” section of this report. 7. Continuous foundation walls should be reinforced top and bottom to span an unsupported length of at least 10 feet. 8. Care should be taken when excavating the foundations to avoid disturbing the supporting materials. Excavation methods which minimize soil disturbance, such as hand excavation or careful soil removal with a backhoe positioned outside of the excavation may be required. 9 Kumar & Associates, Inc 9. The natural fine-grained soils may pump or deform excessively under heavy construction traffic. The use of track-mounted construction equipment and other equipment that exert lower contact pressures than pneumatic tires should be used, and the movement of vehicles over proposed foundation areas should be restricted to help reduce this difficulty. 10. A representative of the geotechnical engineer should observe all footing excavations prior to concrete placement FLOOR SLABS AND EXTERIOR FLATWORK Removal and replacement of existing fill to reduce potential movements (i.e., settlement and/or heave) was discussed previously in the “Geotechnical Engineering Considerations” section of this report. Ideally, all existing fill material should be removed from below floor slabs and exterior flatwork; however, if the owner is willing to accept the risk of movements in excess of normal tolerances associated with leaving some of the existing fill in place, a partial removal alternative may be considered where a minimum of 3 feet of the existing fill material below floor slabs and adjacent exterior flatwork is removed and replaced with structural fill meeting the material and placement criteria provided in the “SITE GRADING” section of this report. To reduce the effects of differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. Joint spacing is dependent on slab thickness, concrete aggregate size, and slump, and should be consistent with recognized guidelines such as those of the Portland Cement Association (PCA) and American Concrete Institute (ACI). The joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. General Floor Slab Recommendations: The following measures should be taken to reduce damage which could result from movement should the underslab materials be subjected to moisture changes. 1. Floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. 2. Floor slabs should not extend beneath exterior doors or over foundation walls, unless saw cut at the wall after construction. 10 Kumar & Associates, Inc 3. Interior non-bearing partitions resting on floor slabs should be provided with slip joints at the tops or bottoms so that, if the slabs move, the movement cannot be transmitted to the upper structure. This detail is also important for wallboards, stairways and door frames. Slip joints which will allow at least 2 inches of vertical movement are recommended. If wood or metal stud partition walls are used, the slip joints should preferably be placed at the bottoms of the walls so differential slab movement won’t damage the partition wall. If slab bearing masonry block partitions are constructed, the slip joints will have to be placed at the tops of the walls. If slip joints are provided at the tops of walls and the floors move, it is likely the partition walls will show signs of distress, such as cracking. An alternative, if masonry block walls or other walls without slip joints at the bottoms are required, is to found them on spread footings and to construct the slabs independently of the foundation. If slab bearing partition walls are required, distress may be reduced by connecting the partition walls to the exterior walls using slip channels. 4. Floor slab control joints should be used to reduce damage due to shrinkage cracking. Joint spacing is dependent on slab thickness, concrete aggregate size, and slump, and should be consistent with recognized guidelines such as those of the Portland Cement Association (PCA) or American Concrete Institute (ACI). We suggest joints be provided on the order of 12 to 15 feet apart in both directions. The requirements for slab reinforcement should be established by the designer based on experience and the intended slab use. 5. If moisture-sensitive floor coverings will be used, mitigation of moisture penetration into the slabs, such as by use of a vapor barrier, may be required. If an impervious vapor barrier membrane is used, special precautions will be required to prevent differential curing problems which could cause the slabs to warp. ACI 302.1R addresses this topic. 6. All plumbing lines should be tested before operation. Where plumbing lines enter through the floor, a positive bond break should be provided. Flexible connections should be provided for slab-bearing mechanical equipment. SITE GRADING Site Preparation: Prior to site grading operations, the large retail building and the smaller structures in the northeast corner will be demolished. All existing foundation elements and floor slabs of these two structures should be completely removed prior to any site grading within these areas. Based on our understanding of the proposed construction and observed site topography, site grading is expected to consist of permanent minor cuts and fills, likely on the order of 2 to 3 feet or less. 11 Kumar & Associates, Inc Material types encountered during site grading will likely consist of sandy clay soils (fill and natural). These materials can be excavated with earth moving equipment typically used for the proposed construction. As indicated previously, all existing fill material beneath foundation areas should be removed. These materials can be replaced, if needed to restore final foundation level elevation(s), with properly compacted structural fill. New structural fill should extend down from the edges of the footings at a 1H:1V (horizontal-to-vertical) projection. The ground surface underlying all fills should be carefully prepared by removing all organic matter and scarification to a minimum depth of 12 inches. The scarified materials should be moisture conditioned and compacted as indicated in the “SITE GRADING” section of this report. If grading is performed during times of cold weather, the fill should not contain frozen materials. If the subgrade is allowed to freeze, all frozen material should be removed prior to additional fill placement or footing, slab or pavement construction. Site grading should be planned to provide positive surface drainage away from all building and parking areas. The buildings and parking areas should be placed as high as possible on the site so that positive drainage away from these features can be provided. Surface diversion features should be provided around parking areas to prevent surface runoff from flowing across the paved surfaces. Cut and Fill Slopes: Permanent unretained cuts in the overburden soils and fill slopes up to 10 feet high should be constructed at a 2H:1V (horizontal-to-vertical) or flatter inclination for stability purposes and at a 3H:1V or flatter inclination for limiting the potential for erosion. If groundwater seepage is encountered during or prior to cut slope excavation, a stability evaluation should be conducted to determine if the seepage would adversely affect the cut Good surface drainage should be provided around all permanent cuts and fills to direct surface runoff away from the slope faces. Fill slopes, cut slopes and other stripped areas should be protected against erosion by vegetation or other methods. Temporary Excavations and Dewatering: Temporary excavations should be constructed in accordance with OSHA requirements, as well as state, local and other applicable requirements. Site excavations will encounter fill and natural clay soils that classify as OSHA Type B soils, although loose areas of fill and/or natural granular soils may classify as OSHA Type C soils. Excavations encountering loose granular soils, or groundwater, will require much shallower side slopes than those allowed by OSHA and/or temporary shoring 12 Kumar & Associates, Inc Material Specifications: Unless specifically modified in the preceding sections of this report, the following recommended material and compaction requirements are presented for compacted fills on the project site. The geotechnical engineer should evaluate the suitability of all proposed fill materials for the project prior to placement. 1. Structural Fill beneath Foundations, Slab-on-Grade Floors, and Settlement-Sensitive Exterior Flatwork: Structural fill should consist of the on-site soils. If needed, imported fill materials should be non-expansive soils with a maximum of 70% passing the No. 200 sieve and a maximum liquid limit and plasticity index of 35 and 20, respectively. Imported fill materials not meeting these criteria may be acceptable if they meet the swell criteria presented in Item 6 below. 2. General Site Grading Fill: Fill placed for general site grading or beneath pavements and exterior flatwork that is not sensitive to settlement should consist of on-site soils, or imported materials if required. 3. Pipe Bedding Material: Pipe bedding material should be a free draining, coarse grained sand and/or fine gravel. The on-site soils are predominantly fine-grained and not suitable for use as pipe bedding. 4. Base Course: Base course material(s) should meet the specifications for Class 5 or Class 6 Aggregate Base Course stated in the current Colorado Department of Transportation (CDOT) “Standard Specifications for Road and Bridge Construction”. 5. Utility Trench Backfill: Materials excavated from utility trenches may be used for trench backfill above the pipe bedding provided they are; not frozen, do not contain unsuitable material or particles larger than 4 inches, and can be placed and compacted as recommended herein. 6. Material Suitability: Unless otherwise defined herein, all fill material should be a non- expansive soil free of vegetation, brush, sod, trash and debris, and other deleterious substances, and should not contain rocks or lumps greater than 4 inches in diameter. Fill material should be considered non-expansive if the material does not swell more than 0.5%, when remolded to 95% of the maximum dry unit weight at optimum moisture content as determined by ASTM D698 and wetted under a 200 psf surcharge pressure. The existing on-site soils should be suitable for use as general site grading fill and as structural fill beneath foundations, floor slabs, exterior slabs, and pavements provided any 13 Kumar & Associates, Inc organic or other deleterious material or debris are removed. Rocks, debris or lumps should be dispersed throughout the fill and concentrations of these materials should be avoided. The geotechnical engineer should evaluate the suitability of proposed import fill materials prior to placement. Evaluation of potential structural fill sources, particularly those not meeting the above liquid limit and plasticity index criteria, should include determination of laboratory moisture-density relationships and swell-consolidation tests on remolded samples prior to acceptance. Placement and Compaction Specifications: We recommend the following moisture content and compaction criteria be used on the project: 1. Moisture Content: Prior to compaction, fill materials should be adjusted to within -1 to + 3 percentage points of optimum moisture content for clayey soils and within ± 2 percentage points of the optimum moisture content for predominantly granular materials. 2. Placement and Degree of Compaction: Unless otherwise defined herein, compacted fill should be placed in maximum 8-inch thick loose lifts. The following compaction criteria should be followed during construction. Percent Fill Location Compaction 1 Beneath Footing Foundations……………………………………………………….…. 98 Adjacent to Footing Foundations………………………………………………………. 95 Wall Backfill: Less than 8 feet BFG 2 ……………………………………………………………… 95 Exterior more than 8 feet BFG……………………………………………………. 98 Settlement Sensitive Areas………………………..……………………………… 98 Beneath Floor Slabs, Settlement-Sensitive Flatwork: Less than 8 feet BFG………………………………..…………………………….. 95 More than 8 feet BFG……………………………..………………………………. 98 Utility Trenches: Interior……………………………………………………………………………….. 98 Exterior - Less than 8 feet BFG…………………………………………………. 95 Exterior - More than 8 feet BFG…………………………………………………. 98 Beneath Pavements: Less than 5 feet BFG………………………………………………………………. 95 More than 5 feet BFG……………………………………………………………… 98 Aggregate Base Course…………………………………………………………… 98 Landscape and Other Areas……………………………………………………………. 90 1 Relative to the maximum dry unit weight as determined by ASTM D 698. 2 BFG = Below Final Grade. 3. Subgrade Preparation: Areas to receive new fill should be prepared as recommended in the specific sections of this report to provide a uniform base for placement of new fill. All other areas to receive new fill not specifically addressed herein should be scarified to a depth of at 14 Kumar & Associates, Inc least 8 inches and recompacted to at least 95% of the maximum dry unit weights as determined by ASTM D698 at moisture contents recommended above. Subgrade preparation should include proof-rolling with a heavily loaded pneumatic-tired vehicle or a heavy, smooth-drum vibratory roller. Areas that deform excessively during proof-rolling should be removed and replaced to achieve a reasonably stable subgrade prior to placement of compacted fill or construction of slabs, flatwork or pavements FOUNDATION WALLS AND RETAINING STRUCTURES Foundation walls and retaining structures associated with the loading docks which are laterally supported and can be expected to undergo only a moderate amount of deflection should be designed for an at-rest lateral earth pressure computed on the basis of an equivalent fluid unit weight of 65 pcf for backfill consisting of the on-site fine-grained soils and 55 pcf for backfill consisting of imported granular materials conforming to CDOT Class 1 Structure Backfill requirements. Cantilevered retaining structures less than 15 feet in height which can be expected to deflect sufficiently to mobilize the full active earth pressure condition should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of 55 pcf for backfill consisting of the on-site soils and 40 pcf for backfill consisting of imported granular materials conforming to CDOT Class 1 Structure Backfill. All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent buildings, traffic, construction materials and equipment. The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a foundation wall or retaining structure. WATER SOLUBLE SULFATES The concentrations of water-soluble sulfates measured in 3 samples of the overburden soils from the exploratory borings range from non-detectable to 0.01%. These concentrations of water-soluble sulfates represent a Class 0 severity of potential exposure to sulfate attack on concrete exposed to these materials. The degrees of severity of potential exposure range from Class 0 to Class 3 as presented in ACI 201.2R-08. Based on the water-soluble sulfate concentrations measured, we believe that no special requirements for sulfate resistance of the cementitious material(s) will be required for concrete exposed to the on-site soils. 15 Kumar & Associates, Inc SURFACE DRAINAGE Proper surface drainage is very important for acceptable performance of site structures during construction and after the construction has been completed. Drainage recommendations provided by local, state and national entities should be followed based on the intended use of each structure. The following recommendations should be used as guidelines and changes should be made only after consultation with the geotechnical engineer. 1. Excessive wetting or drying of the foundation and slab subgrade(s) should be avoided during construction. 2. Exterior backfill meet the material and placement requirements outlined in the “SITE GRADING” section of this report. 3. Care should be taken when compacting around the foundation walls and underground structures to avoid damage to the structures. Hand compaction procedures, if necessary, should be used to prevent lateral pressures from exceeding the design values. 4. The ground surface surrounding the exterior of site structures should be sloped to drain away from the foundations in all directions. We recommend a minimum slope of 12 inches in the first 10 feet in unpaved areas. Site drainage beyond the 10-foot zone should be designed to promote runoff and reduce infiltration. A minimum slope of 3 inches in the first 10 feet is recommended in the paved areas. These slopes may be changed as required for handicap access points in accordance with the Americans with Disabilities Act. 5. The upper 2 feet of the backfill should be relatively impervious material compacted as recommended above to limit infiltration of surface runoff. 6. Ponding of water should not be allowed in backfill material or within 10 feet of the foundations, whichever is greater. 7. Roof downspouts and drains should discharge well beyond the limits of all backfill. 8. Landscaping which requires relatively heavy irrigation and lawn sprinkler heads should be located at least 10 feet from foundations. Irrigation schemes are available which allow placement of lightly irrigated landscape near foundation walls in moisture sensitive soil areas. Drip irrigation heads with main lines located at least 10 feet from the foundation walls are acceptable provided irrigation quantities are limited. 16 Kumar & Associates, Inc 9. Plastic membranes should not be used to cover the ground surface adjacent to foundation walls. PAVEMENT THICKNESS DESIGN A pavement section is a layered system designed to distribute concentrated traffic loads to the subgrade. Performance of the pavement structure is directly related to the physical properties of the subgrade soils and traffic loadings. Soils are represented for pavement design purposes by means of the subgrade resilient modulus, MR, for flexible pavements and the modulus of subgrade reaction, k, for rigid pavements. Both values are empirically related to strength. Subgrade Materials: The results of the field and laboratory studies indicate the pavement subgrade materials across the site are expected to consist of sandy clay, fill and natural. Based on laboratory test results, the subgrade materials at the site predominantly classify as A-6 and A-7-6 soils with group indices between 0 and 23 in accordance with the American Association of State Highway and Transportation Officials (AASHTO) soil classification system. Soils classifying between A-6 and A-7- 6 are generally considered to provide poor subgrade support. For design purposes, a resilient modulus value of 3,025 psi was selected for flexible pavements and a modulus of subgrade reaction of 40 pci was selected for rigid pavements. Design Traffic: Since anticipated traffic loading information was not available at the time of this report preparation, an 18-kip equivalent single axle loading (ESAL) value of 73,000 was assumed for the paved parking surfaces and an ESAL of 219,000 was assumed for truck routes. The values are selected based on our past experience for facilities of this nature. The Kroger Site Development Standards identify a “Light Duty” and a “Heavy Duty” pavement thickness requirement for projects constructed under their jurisdiction. We believe that the ESAL values of 73,000 and 219,000 should be considered to classify as Light Duty and Heavy Duty pavement sections, respectively. The Heavy Duty pavement section should be constructed in locations of heavy vehicular traffic movements such as truck and tanker routes. If estimated daily traffic volumes for the development are known to be different from those assumed, we should be provided with this information in order to re-evaluate the pavement sections provided below. Existing Pavement: Typical rehabilitation strategies for reuse of existing pavements include an asphalt overlay that may include surface-milling prior to placement of the new overlay. The overlay analysis is based on the AASHTO Component Analysis approach where a structural coefficient for the existing asphalt is used depending upon the condition of the asphalt. A structural coefficient is 17 Kumar & Associates, Inc also included for existing aggregate base course. In our opinion, based on the overall poor condition of the existing pavement due to the amount and severity of the distresses observed, little structural contribution (i.e., a low structural coefficient) would be provided by the existing pavement. Any surface-milling to address the distresses would reduce the thickness of the existing asphalt, thereby reducing the overall structural contribution further. Additionally, there would be no structural contribution from an aggregate base course layer and the soils at the site are poor subgrade support materials. Therefore, in our opinion, reuse of the existing asphalt pavement is not recommended, and the proposed paved driveways and parking areas should be fully reconstructed pavement sections. Pavement Design: Alternatives for flexible pavements of full-depth hot mix asphalt (HMA) or a composite section of HMA over aggregate base course (ABC), and rigid pavements of Portland cement concrete (PCC) are presented in the table below. The pavement sections were determined in accordance with the 1993 AASHTO pavement design procedures. LOCATION Pavement Section Thicknesses (inches) Full-Depth Hot Mix Asphalt Hot Mix Asphalt over Aggregate Base Course Portland Cement Concrete Light Duty 7 4½ over 8 6 Heavy Duty 8½ 5½ over 9 7 *Light Duty: Automobile parking; Heavy Duty: Access drives, fire lanes. Truck loading dock areas and other areas where truck turning movements are concentrated should be paved with 8 inches of Portland Cement Concrete (PCC). The PCC pavement should contain sawed or formed joints to ¼ of the depth of the slab at a maximum distance of 12 feet on center. Concrete pavements may be a suitable alternative for parking lots, the fuel center and delivery areas. Pavement Materials: The following are recommended material and placement requirements for pavement construction for this project site. We recommend that properties and mix designs for all materials proposed to be used for pavements be submitted for review to the geotechnical engineer prior to placement. 1. Aggregate Base Course: Aggregate base course (ABC) used beneath HMA pavements should meet the material specifications for Class 5 or Class 6 ABC stated in the current Colorado Department of Transportation (CDOT) “Standard Specifications for Road and Bridge Construction”. The ABC should be placed and compacted as outlined in the “SITE GRADING” section of this report. 18 Kumar & Associates, Inc 2. Hot Mix Asphalt: Hot mix asphalt (HMA) materials and mix designs should meet the applicable requirements indicated in the current CDOT “Standard Specifications for Road and Bridge Construction”. We recommend that the HMA used for this project be designed in accordance with the SuperPave gyratory mix design method. The mix should generally meet Grading S or SX specifications with a SuperPave gyratory design revolution (NDESIGN) of 75. The mix design for the HMA should use a performance grade PG 58-28 or PG 64-22 asphalt binder. Placement and compaction of HMA should follow current CDOT standards and specifications. 3. Portland Cement Concrete: Portland Cement Concrete (PCC) pavement should meet Class P specifications and requirements in the current CDOT “Standard Specifications for Road and Bridge Construction”. The owner should be aware that rigid PCC pavements will be less tolerant of differential settlement or heave-related movement than flexible asphalt pavements. Where rigid PCC pavement is constructed, providing reinforcing and doweling as discussed below would help reduce the risk of pavement distress due to differential settlement or heave-related movement. The above PCC pavement thicknesses are presented as un-reinforced slabs. Based on projects with similar heavy vehicular loading in certain areas, we recommend that dowels be provided at transverse and longitudinal joints within the slabs located in the travel lanes of heavily loaded vehicle, loading docks and areas where truck turning movements are likely to be concentrated. Additionally, curbs and/or pans should be tied to the slabs. The dowels and tie bars will help minimize the risk for differential movements between slabs to assist in more uniformly transferring axle loads to the subgrade. The current CDOT “Standard Specifications for Road and Bridge Construction” provides some guidance on dowel and tie bar placement, as well as in the Standard Plans: M&S Standards. The PCC pavement should contain sawed or formed joints to ¼ of the depth of the slab at a maximum distance of 12 to 15 feet on center. The proper sealing and maintenance of joints to minimize the infiltration of surface water is critical to the performance of PCC pavement, especially if dowels and tie bars are not installed. Subgrade Preparation: Prior to placing new fill or the pavement section, the entire subgrade area should be thoroughly scarified and well-mixed to a depth of 12 inches, adjusted to a moisture content and compacted as indicated in the “SITE GRADING” section of this report. Fill placed 19 Kumar & Associates, Inc beneath the pavement should meet the material and compaction requirements for structural fill presented in the “SITE GRADING” section of this report. Pavement design procedures assume a stable subgrade and the pavement subgrade should be proof-rolled, preferably within 48 hours prior to paving. The proof-roll should be performed using a heavily loaded pneumatic-tired vehicle such as a loaded water truck or large front-end loader. Areas that deform under wheel loads that are not stable should be removed and replaced to achieve a stable subgrade prior to paving. The contractor should be aware that the clay soils and claystone may become somewhat unstable and deform under wheel loads if placed near the upper end of the moisture content range. Drainage: The collection and diversion of surface drainage away from paved areas is extremely important to the satisfactory performance of pavement. Drainage design should provide for the removal of water from paved areas and prevent the wetting of the subgrade soils. DESIGN AND CONSTRUCTION SUPPORT SERVICES Kumar & Associates, Inc. should be retained to review the project plans and specifications for conformance with the recommendations provided in our report. We are also available to assist the design team in preparing specifications for geotechnical aspects of the project, and performing additional studies if necessary to accommodate possible changes in the proposed construction. We recommend that Kumar & Associates, Inc. be retained to provide construction observation and testing services to document that the intent of this report and the requirements of the plans and specifications are being followed during construction. This will allow us to identify possible variations in subsurface conditions from those encountered during this study and to allow us to re-evaluate our recommendations, if needed. We will not be responsible for implementation of the recommendations presented in this report, if we are not retained to provide construction observation and testing services. LIMITATIONS This study has been conducted in accordance with generally accepted geotechnical engineering practices in this area for exclusive use by the client for design purposes. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory borings at the locations indicated on Fig. 1, and the proposed type of construction. This report may not reflect subsurface variations that occur between the exploratory borings, and the nature and extent of variations across the site may not become evident until site grading and excavations are 20 Kumar & Associates, Inc performed. If during construction, fill, soil, rock or water conditions appear to be different from those described herein, Kumar & Associates, Inc. should be advised at once so that a re-evaluation of the recommendations presented in this report can be made. Kumar & Associates, Inc. is not responsible for liability associated with interpretation of subsurface data by others. Swelling soils and bedrock occur on this site. Such soils are stable at their natural moisture content but will undergo high volume changes with changes in moisture content. The extent and amount of perched water beneath the building site as a result of area irrigation and inadequate surface drainage is difficult, if not impossible, to foresee. The recommendations presented in this report are based on current theories and experience of our engineers on the behavior of swelling soil in this area. The owner should be aware that there is a risk in constructing a building in an expansive soil area. Following the recommendations given by a geotechnical engineer, careful construction practice and prudent maintenance by the owner can, however, decrease the risk of foundation movement due to expansive soils. DC/jan/es cc: book, file Project No.: Project Name: Date(s) Sampled: Date(s) Received: Boring Gravel (%) Sand (%) Liquid Limit (%) Plasticity Index (%) B-1 18.5 107.7 6 59 35 31 12 A-7-6 (0) Clayey Sand (SC) B-2 9.3 103.1 1 39 60 33 15 A-6 (6) Sandy Lean Clay (CL) B-3 19.5 107.6 11 22 67 34 20 A-6 (11) Fill: Lean Clay with Sand (CL) B-3 22.3 97.2 Lean to Sandy Lean Clay (CL) B-3 10.5 118.6 Silty, Clayey Sand (SC-SM) B-3 27.2 96.2 Lean to Sandy Lean Clay (CL) B-3 24.6 99.7 Lean to Sandy Lean Clay (CL) B-3 23.6 103.2 Lean to Sandy Lean Clay (CL) B-4 22.8 98.1 85 38 18 A-6 (15) Fill: Lean Clay with Sand (CL) B-5 22.2 99.1 88 38 19 ND A-6 (17) Lean Clay (CL) B-6 16.8 102.8 2 27 71 33 15 A-6 (9) Fill: Lean Clay with Sand (CL) B-7 15.2 103.8 20 20 60 34 15 A-6 (7) Fill: Sandy Lean Clay with Gravel (CL) B-8 21.0 104.5 72 36 20 A-6 (12) Fill: Sandy Lean Clay (CL) B-9 14.8 108.4 88 35 18 A-6 (15) Fill: Lean Clay (CL) B-10 19.7 105.0 Fill: Lean to Sandy Lean Clay (CL) B-10 19.5 99.5 0.01 Lean to Sandy Lean Clay (CL) B-10 8.2 121.6 11 66 23 NV NP A-1-b (0) Silty Sand (SM) B-10 24.8 99.6 Lean to Sandy Lean Clay (CL) B-10 26.1 98.1 Lean to Sandy Lean Clay (CL) B-10 15.6 112.3 Poorly-Graded to Silty Sand (SP, SP-SM) B-10 18.2 106.6 Sandstone B-11 15.8 111.3 88 39 20 A-6 (18) Fill: Lean Clay (CL) B-12 16.7 106.8 64 37 23 A-6 (12) Fill: Sandy Lean Clay (CL) B-13 17.3 103.0 78 40 26 A-6 (19) Fill:Lean Clay with Sand (CL) B-14 18.1 104.5 84 35 17 ND A-6 (13) Fill: Lean Clay with Sand (CL) B-16 18.9 108.7 82 44 29 A-7-6 (23) Fill: Lean Clay with Sand (CL) B-16 18.4 105.7 68 40 29 A-6 (17) Sandy Lean Clay (CL) B-17 11.4 111.2 76 35 19 A-6 (13) Fill: Lean Clay with Sand (CL) B-19 16.4 111.4 1 29 70 Fill: Sandy Lean Clay (CL) B-20 12.6 112.8 15 24 61 34 14 A-6 (6) Fill: Sandy Lean Clay with Gravel (CL) B-12 &15* 4 29 67 34 13 < 5 A-6 (7) Sandy Lean Clay (CL) * Composite sample. 1 1 1 1 - 4 4 4 34 1 29 4 1 4 1 1 1 4 9 14 19 4 4 24 4 4 Summary of Laboratory Test Results Table I Sample Location Natural Gradation Atterberg Limits Moisture Content (%) Natural Dry Unit Weight (pcf) Percent Passing No. 200 Sieve Depth (Feet) AASHTO Classification (Group Index) Soil or Bedrock Type October 25 & 28; November 1 & 2, 2016 16-3-183 King Soopers #146 19 14 9 4 1 November 1 & 2, 2016 R-Value 4 1 Water Soluble Sulfates (%)