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HomeMy WebLinkAboutLOFTS AT TIMBERLINE - FDP200007 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT400 North Link Lane | Fort Collins, Colorado 80524 Telephone: 970-206-9455 Fax: 970-206-9441 GEOTECHNICAL INVESTIGATION PROPOSED COMMERCIAL BUILDING LOTS 4, 6, AND 7, TIMBERLINE CENTER FORT COLLINS, COLORADO DITESCO 2133 South Timberline Road, Unit 110 Fort Collins, Colorado 80525 Attention: Mr. Keith Meyer, PE Project No. FC08890-125 June 3, 2019 DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE CONDITIONS 2 PROPOSED CONSTRUCTION 2 INVESTIGATION 2 PREVIOUS INVESTIGATIONS 3 SUBSURFACE CONDITIONS 3 Groundwater 3 SEISMICITY 4 SITE DEVELOPMENT 4 Fill Placement 4 Excavations 5 FOUNDATIONS 5 Spread Footings 6 BELOW GRADE AREAS 7 FLOOR SYSTEMS 7 PAVEMENTS 9 Pavement Selection 10 Subgrade and Pavement Materials and Construction 10 Pavement Maintenance 11 WATER-SOLUBLE SULFATES 11 SURFACE DRAINAGE 12 LIMITATIONS 12 DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS FIGURE 2 – SUMMARY LOGS OF EXPLORATORY BORINGS APPENDIX A – RESULTS OF LABORATORY TESTING APPENDIX B – SAMPLE SITE GRADING SPECIFICATIONS APPENDIX C – PAVEMENT CONSTRUCTION RECOMMENDATIONS APPENDIX D – PAVEMENT MAINTENANCE PROGRAM DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 1 SCOPE This report presents the results of our Geotechnical Investigation for the proposed commercial building on Lots 4, 6, and 7 of Timberline Center in Fort Collins, Colorado. The purpose of the investigation was to evaluate the subsur- face conditions and provide foundation recommendations and geotechnical de- sign criteria for the project. The scope was described in our Service Agreement (FC-19-0177, dated April 26, 2019). The report was prepared from data developed during field exploration, la- boratory testing, engineering analysis and experience with similar conditions. The report includes a description of subsurface conditions found in our explora- tory borings and discussions of site development as influenced by geotechnical considerations. Our opinions and recommendations regarding design criteria and construction details for site development, foundations, floor systems, slabs- on-grade, pavements and drainage are provided. If the proposed construction changes, we should be requested to review our recommendations. Our conclu- sions are summarized in the following paragraphs. SUMMARY OF CONCLUSIONS 1. Soils encountered in our borings consisted of 18 to 21 feet of sandy clay over sand and gravel. Claystone bedrock was encountered in one boring at 28 feet to the depth explored. 2. Groundwater was encountered in two borings at 23 feet during drill- ing and 22 and 22½ feet when measured several days later. Exist- ing groundwater levels are not expected to significantly affect site development. 3. We believe the proposed structure can be constructed on spread footing foundations placed on natural, undisturbed soil and/or properly compacted fill. Foundation design and construction rec- ommendations are presented in this report. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 2 4. We believe slab-on-grade floors are appropriate for this site. Some movement of slab-on-grade floors should be anticipated. We ex- pect movements will be minor, on the order of 1 inch or less. If movement cannot be tolerated, structural floors should be consid- ered. 5. Pavement subgrade at this site consists of sandy clay that gener- ally classifies as A-6 material according to AASHTO criteria. Rec- ommended pavement thicknesses and material alternatives are dis- cussed in this report. SITE CONDITIONS The site is located at 2021, 2027, and 2033 South Timberline Road in Fort Collins, Colorado (Figure 1). The lot is undeveloped and generally flat. Ground cover consisted of natural grasses and weeds. PROPOSED CONSTRUCTION Two conceptual plans were provided for the proposed development. Site Concept No. 1 indicated two office and warehouse buildings: one 40,000 square feet and one 8,100 square feet. Site Concept No. 2 indicates one 49,900 square-foot building for office and warehouse units. The project will include as- sociated parking areas and access drives. No below grade areas are planned. INVESTIGATION Subsurface conditions were investigated by drilling three borings to depths of approximately 20 and 30 feet. The approximate locations of the borings are shown on Figure 1. Our field representative observed drilling, logged the soils and bedrock found in the borings and obtained samples. Sampling was per- formed by driving a 2.5-inch O.D. modified California sampler with blows of a 140-pound hammer falling 30 inches. This method is similar to the standard pen- etration test, and is typical for local practice. Groundwater measurements were taken during drilling and several days after drilling. Summary logs of the borings, including results of field penetration resistance tests, are presented on Figure 2. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 3 Samples obtained during drilling were returned to our laboratory and visu- ally examined by the geotechnical engineer for this project. Laboratory analyses included moisture content, dry density, swell-consolidation, particle-size anal- yses, Atterberg limits, and water-soluble sulfate tests. Results of laboratory tests are presented in Appendix A and summarized in Table A-I. PREVIOUS INVESTIGATIONS CTL|Thompson, Inc. previously performed a preliminary investigation for this area (Project No. FC03553-115, report dated August 9, 2005). Information from our previous report, including exploratory borings and laboratory testing, was considered in the preparation of this report. SUBSURFACE CONDITIONS Soils encountered in our borings consisted of 18 to 21 feet of sandy clay over sand and gravel. Claystone bedrock was encountered in one boring at 28 feet to the depth explored. The upper 4 feet of soils encountered in one boring was considered fill. Samples tested indicated nil to 2.3 percent swell. Further description of the subsurface conditions is presented on our boring logs (Figure 2) and in our laboratory testing (Appendix A). Groundwater Groundwater was encountered in two borings at 23 feet during drilling and 22 and 22½ feet when measured several days later. Groundwater will fluctuate seasonally. Existing groundwater levels are not expected to significantly affect site development. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 4 SEISMICITY This area, like most of central Colorado, is subject to a low degree of seis- mic risk. As in most areas of recognized low seismicity, the record of the past earthquake activity in Colorado is incomplete. According to the 2012 International Building Code and the subsurface con- ditions encountered in our borings, this site classifies as Site Class D. Only mi- nor damage to relatively new, properly designed and built buildings would be ex- pected. Wind loads, not seismic considerations, typically govern dynamic struc- tural design in this area. SITE DEVELOPMENT Fill Placement The existing onsite soils are suitable for re-use as fill material provided de- bris or deleterious organic materials are removed. If import material is used, it should be tested and approved as acceptable fill by CTL|Thompson. In general, import fill should meet or exceed the engineering qualities of the onsite soils. Ar- eas to receive fill should be scarified, moisture-conditioned and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D698, AASHTO T99). Sand soils used as fill should be moistened to within 2 percent of optimum moisture content. Clay soils should be moistened between optimum and 3 percent above optimum moisture content. The fill should be moisture-con- ditioned, placed in thin, loose lifts (8 inches or less) and compacted as described above. We should observe placement and compaction of fill during construction. Fill placement and compaction should not be conducted when the fill material is frozen. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 5 Site grading in areas of landscaping where no future improvements are planned can be placed at a dry density of at least 90 percent of standard Proctor maximum dry density (ASTM D 698, AASHTO T 99). Example site grading spec- ifications are presented in Appendix B. Water and sewer lines are often constructed beneath areas where im- provements are planned. Compaction of trench backfill can have a significant ef- fect on the life and serviceability overlying structures. We recommend trench backfill be moisture conditioned and compacted as described in the Fill Place- ment section of this report. Placement and compaction of fill and backfill should be observed and tested by a representative of our firm during construction. Excavations The materials found in our borings can be excavated using conventional heavy-duty excavation equipment. Excavations should be sloped or shored to meet local, State and Federal safety regulations. Excavation slopes specified by OSHA are dependent upon types of soil and groundwater conditions encoun- tered. The contractor’s “competent person” should identify the soils and/or rock encountered in the excavation and refer to OSHA standards to determine appro- priate slopes. Stockpiles of soils, rock, equipment, or other items should not be placed within a horizontal distance equal to one-half the excavation depth, from the edge of excavation. Excavations deeper than 20 feet should be braced or a professional engineer should design the slopes. FOUNDATIONS Soils encountered in our investigation were primarily low-swelling or non- expansive. Spread footing foundations are appropriate for the proposed struc- tures. Foundations should not be constructed on the exiting fill. The fill should be removed and replaced with properly compacted soil or foundations should ex- tend through the fill. Design criteria for spread footing foundations developed DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 6 from analysis of field and laboratory data and our experience are presented be- low. Spread Footings 1. Footings should be constructed on undisturbed natural soils or properly compacted fill (see the Fill Placement section of this re- port). All existing man-placed fill should be removed from under footings and within one footing width around footings and replaced with engineered fill. Where soil is loosened during excavation, it should be removed and replaced with on-site soils compacted fol- lowing the criteria in the Fill Placement section of this report. 2. Footings constructed on the natural soils and/or engineered fill can be designed for a net allowable soil pressure of 1,500 psf. The soil pressure can be increased 33 percent for transient loads such as wind or seismic loads. 3. Footings should have a minimum width of at least 16 inches. Foun- dations for isolated columns should have minimum dimensions of 18 inches by 18 inches. Larger sizes may be required depending on loads and the structural system used. 4. The soils beneath footing pads can be assigned an ultimate coeffi- cient of friction of 0.45 to resist lateral loads. The ability of grade beam or footing backfill to resist lateral loads can be calculated us- ing a passive equivalent fluid pressure of 250 pcf. This assumes the backfill is densely compacted and will not be removed. Backfill should be placed and compacted to the criteria in the Fill Place- ment section of this report. 5. Exterior footings should be protected from frost action. We believe 30 inches of frost cover is appropriate for this site. 6. Foundation walls and grade beams should be well reinforced both top and bottom. We recommend the amount of steel equivalent to that required for a simply supported span of 10 feet. 7. We should observe completed footing excavations to confirm that the subsurface conditions are similar to those found in our borings. Occasional loose soils may be found in foundation excavations. If this occurs, we recommend the loose soils be treated as discussed in Item 1 above. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 7 BELOW GRADE AREAS No basement areas are planned for the building. For this condition, perim- eter drains are not usually necessary. We should be contacted to provide founda- tion drain recommendations if plans change to include basement areas. FLOOR SYSTEMS In our opinion, it is reasonable to use slab-on-grade floors for the pro- posed construction. Foundations should not be constructed on the exiting fill. The fill should be removed and replaced with properly compacted soil. Any fill placed for the floor subgrade should be built with densely compacted, engineered fill as discussed in the Fill Placement section of this report. It is impossible to construct slab-on-grade floors with no risk of movement. We believe movements due to swell will be less than 1 inch at this site. If move- ment cannot be tolerated, structural floors should be used. Structural floors can be considered for specific areas that are particularly sensitive to movement or where equipment on the floor is sensitive to movement. Where structurally supported floors are selected, we recommend a mini- mum void between the ground surface and the underside of the floor system of 4 inches. The minimum void should be constructed below beams and utilities that penetrate the floor. The floor may be cast over void form. Void form should be chosen to break down quickly after the slab is placed. We recommend against the use of wax or plastic-coated void boxes. Slabs may be subject to heavy point loads. The structural engineer should design floor slab reinforcement. For design of slabs-on-grade, we recom- mend a modulus of subgrade reaction of 50 pci for on-site soils. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 8 If the owner elects to use slab-on-grade construction and accepts the risk of movement and associated damage, we recommend the following precautions for slab-on-grade construction at this site. These precautions can help reduce, but not eliminate, damage or distress due to slab movement. 1. Slabs should be separated from exterior walls and interior bearing members with a slip joint that allows free vertical movement of the slabs. This can reduce cracking if some movement of the slab oc- curs. 2. Slabs should be placed directly on exposed soils or properly mois- ture conditioned, compacted fill. The 2012 International Building Code (IBC) requires a vapor retarder be placed between the base course or subgrade soils and the concrete slab-on-grade floor. The merits of installation of a vapor retarder below floor slabs depend on the sensitivity of floor coverings and building use to moisture. A properly installed vapor retarder (10 mil minimum) is more benefi- cial below concrete slab-on-grade floors where floor coverings, painted floor surfaces or products stored on the floor will be sensi- tive to moisture. The vapor retarder is most effective when con- crete is placed directly on top of it, rather than placing a sand or gravel leveling course between the vapor retarder and the floor slab. The placement of concrete on the vapor retarder may in- crease the risk of shrinkage cracking and curling. Use of concrete with reduced shrinkage characteristics including minimized water content, maximized coarse aggregate content, and reasonably low slump will reduce the risk of shrinkage cracking and curling. Con- siderations and recommendations for the installation of vapor re- tarders below concrete slabs are outlined in Section 3.2.3 of the 2006 report of American Concrete Institute (ACI) Committee 302, “Guide for Concrete Floor and Slab Construction (ACI 302.R1-04)”. 3. If slab-bearing partitions are used, they should be designed and constructed to allow for slab movement. At least a 2-inch void should be maintained below or above the partitions. If the “float” is provided at the top of partitions, the connection between interior, slab-supported partitions and exterior, foundation supported walls should be detailed to allow differential movement. 4. Underslab plumbing should be eliminated where feasible. Where such plumbing is unavoidable it should be thoroughly pressure tested for leaks prior to slab construction and be provided with flexi- ble couplings. Pressurized water supply lines should be brought above the floors as quickly as possible. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 9 5. Plumbing and utilities that pass through the slabs should be iso- lated from the slabs and constructed with flexible couplings. Where water and gas lines are connected to furnaces or heaters, the lines should be constructed with sufficient flexibility to allow for move- ment. 6. HVAC equipment supported on the slab should be provided with a collapsible connection between the furnace and the ductwork, with allowance for at least 2 inches of vertical movement. 7. The American Concrete Institute (ACI) recommends frequent con- trol joints be provided in slabs to reduce problems associated with shrinkage cracking and curling. To reduce curling, the concrete mix should have a high aggregate content and a low slump. If desired, a shrinkage compensating admixture could be added to the con- crete to reduce the risk of shrinkage cracking. We can perform a mix design or assist the design team in selecting a pre-existing mix. PAVEMENTS The project will include a paved parking lot and access drives. The perfor- mance of a pavement structure is dependent upon the characteristics of the sub- grade soil, traffic loading and frequency, climatic conditions, drainage and pave- ment materials. Subgrade soil at this site generally classifies as A-6 according to AASHTO criteria, with expected fair to poor subgrade support. We anticipate flexible hot mix asphalt (HMA) pavement is planned for the parking lot. Rigid portland cement concrete (PCC) pavement should be consid- ered for trash enclosure areas and where the pavement will be subjected to fre- quent turning of heavy vehicles. Alternatives that include each material are pro- vided below. Our designs are based on the AASHTO design method and our ex- perience. Using the criteria discussed above we recommend the minimum pave- ment sections provided in Table A. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 10 TABLE A RECOMMENDED PAVEMENT SECTIONS Classification Hot Mix Asphalt (HMA) + Aggregate Base Course (ABC) Portland Cement Concrete (PCC) Parking Area 4" HMA + 6" ABC 6" PCC Access Drives 5" HMA + 6" ABC 6"PCC Trash Enclosures - 6" PCC Pavement Selection Composite HMA/ABC pavement over a stable subgrade is expected to perform well at this site based on the recommendations provided. HMA provides a stiff, stable pavement to withstand heavy loading and will provide a good fa- tigue resistant pavement. However, HMA does not perform well where point loads are subjected and in areas where heavy trucks turn and maneuver at slow speeds. PCC pavement is also expected to perform well in this area. PCC pavement has better performance in freeze-thaw conditions and should require less long-term maintenance than HMA pavement. In any event, the performance of the pavement structure depends partly on the stability of the subgrade soils. Subgrade and Pavement Materials and Construction The design of a pavement system is as much a function of the quality of the paving materials and construction as the support characteristics of the sub- grade. Moisture treatment criteria and additional criteria for materials and con- struction requirements are presented in Appendix C of this report. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 11 Pavement Maintenance Routine maintenance, such as sealing and repair of cracks, is necessary to achieve the long-term life of a pavement system. We recommend a preven- tive maintenance program be developed and followed for all pavement systems to assure the design life can be realized. Choosing to defer maintenance usually results in accelerated deterioration leading to higher future maintenance costs, and/or repair. A recommended maintenance program is outlined in Appendix D. Excavation of completed pavement for utility construction or repair can de- stroy the integrity of the pavement and result in a severe decrease in serviceabil- ity. To restore the pavement top original serviceability, careful backfill compac- tion before repaving is necessary. WATER-SOLUBLE SULFATES Concrete that comes into contact with soils can be subject to sulfate at- tack. We measured water-soluble sulfate concentrations in two samples from this site. Concentrations were at or below 0.01 percent. Sulfate concentrations less than 0.1 percent indicate Class 0 exposure to sulfate attack for concrete that comes into contact with the subsoils, according to the American Concrete Insti- tute (ACI). For this level of sulfate concentration, ACI indicates any type of ce- ment can be used for concrete that comes into contact with the soils and/or bed- rock. In our experience, superficial damage may occur to the exposed surfaces of highly permeable concrete, even though sulfate levels are relatively low. To control this risk and to resist freeze-thaw deterioration, the water-to-cementitious material ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high water tables. Concrete should be air entrained. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 12 SURFACE DRAINAGE Performance of foundations, flatwork and pavements are influenced by changes in subgrade moisture conditions. Carefully planned and maintained sur- face grading can reduce the risk of wetting of the foundation soils and pavement subgrade. Positive drainage should be provided away from foundations. Backfill around foundations should be moisture treated and compacted as described in Fill Placement. Roof drains should be directed away from buildings. Downspout extensions and splash blocks should be provided at discharge points. LIMITATIONS Although our borings were spaced to obtain a reasonably accurate picture of subsurface conditions, variations not indicated in our borings are possible. We should observe footing excavations to confirm soils are similar to those found in our borings. Placement and compaction of fill, backfill, subgrade and other fills should be observed and tested by a representative of our firm during construc- tion. This report was prepared from data developed during our field exploration, laboratory testing, engineering analysis and experience with similar conditions. The recommendations contained in this report were based upon our understand- ing of the planned construction. If plans change or differ from the assumptions presented herein, we should be contacted to review our recommendations. We believe this investigation was conducted in a manner consistent with that level of skill and care ordinarily used by members of the profession currently practicing under similar conditions in the locality of this project. No warranty, ex- press or implied, is made. TH-1 TBM TH-2 TH-3 Bear Mountain Drive Joseph Allen Drive PROSPECT RD. DRAKE RD. TIMBERLINE RD. LEMAY AVE. SITE JOSEPH ALLEN DR. LEGEND: INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING INDICATES APPROXIMATE LOCATION OF TEMPORARY BENCHMARK; TOP OF CURB (ASSUMED ELEVATION 100') TH-1 TBM DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL I T PROJECT NO. FC08890-125 FIGURE 1 Locations of Exploratory Borings VICINITY MAP (FORT COLLINS, COLORADO) NOT TO SCALE 40' 80' APPROXIMATE SCALE: 1" = 80' 0' 55 60 65 70 75 80 85 90 95 100 55 60 65 70 75 80 85 90 95 100 ELEVATION - FEET FIGURE 2 DRIVE SAMPLE. THE SYMBOL 5/12 INDICATES 5 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. ELEVATION - FEET WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. CLAY, SANDY, MOIST, MEDIUM STIFF TO VERY STIFF, BROWN, REDDISH BROWN (CL) 2. 3. FILL, CLAY, SANDY WITH OCCASIONAL GRAVEL AND COBBLE, MOIST, MEDIUM STIFF, BROWN, DARK BROWN THE BORINGS WERE DRILLED ON MAY 9, 2019 USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. 1. LEGEND: NOTES: SAND AND GRAVEL, MOIST TO WET, VERY DENSE, BROWN (SP, GP) CLAYSTONE, MOIST, VERY HARD, BROWN, GRAY, RUST WATER LEVEL MEASURED AT TIME OF DRILLING. BORING ELEVATIONS WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM REFERENCING THE TEMPORARY BENCHMARK SHOWN ON FIGURE 1. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. 4. Summary Logs of Exploratory Borings WC DD SW -200 LL PI UC SS - - - - - - APPENDIX A RESULTS OF LABORATORY TESTING Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 102 PCF From TH - 1 AT 4 FEET MOISTURE CONTENT= 10.4 % DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL | T PROJECT NO. FC08890-125 APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-1 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 NO MOVEMENT DUE TO WETTING 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 119 PCF From TH - 1 AT 14 FEET MOISTURE CONTENT= 13.9 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 111 PCF From TH - 2 AT 9 FEET MOISTURE CONTENT= 16.7 % DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL | T PROJECT NO. FC08890-125 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-2 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING -4 -3 -2 -1 0 1 2 3 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 107 PCF From TH - 2 AT 19 FEET MOISTURE CONTENT= 18.1 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 110 PCF From TH - 3 AT 4 FEET MOISTURE CONTENT= 7.0 % DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL | T PROJECT NO. FC08890-125 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-3 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 NO MOVEMENT DUE TO WETTING -3 -2 -1 0 1 2 3 4 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 118 PCF From TH - 3 AT 14 FEET MOISTURE CONTENT= 14.4 % DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL | T PROJECT NO. FC08890-125 APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-4 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) GRAVEL 0 % SAND 18 % From TH - 3 AT 9 FEET SILT & CLAY 82 % LIQUID LIMIT 40 % PLASTICITY INDEX 25 % Sample of GRAVEL % SAND % From SILT & CLAY % LIQUID LIMIT % PLASTICITY INDEX % DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL | T PROJECT NO. FC08890-125 FIGURE A-5 Gradation Test Results 0.002 15 MIN. .005 60 MIN. .009 19 MIN. .019 4 MIN. .037 1 MIN. .074 *200 .149 *100 .297 *50 0.42 *40 .590 *30 1.19 *16 2.0 *10 2.38 *8 4.76 *4 9.52 3/8" 19.1 3/4" 36.1 1½" 76.2 3" 127 5" 152 6" 200 8" .001 45 MIN. 0 10 PASSING WATER- MOISTURE DRY LIQUID PLASTICITY APPLIED SWELL NO. 200 SOLUBLE DEPTH CONTENT DENSITY LIMIT INDEX SWELL* PRESSURE PRESSURE SIEVE SULFATES BORING (FEET) (%) (PCF) (%) (PSF) (PSF) (%) (%) DESCRIPTION TH-1 4 10.4 102 0.0 500 <0.01 CLAY, SANDY (CL) TH-1 14 13.9 119 0.1 1,800 2,400 CLAY, SANDY (CL) TH-2 9 16.7 111 0.2 1,100 1,600 <0.01 CLAY, SANDY (CL) TH-2 19 18.1 107 0.0 2,400 CLAY, SANDY (CL) TH-3 4 7.0 110 2.3 500 CLAY, SANDY (CL) TH-3 9 15.1 115 40 25 82 CLAY, SANDY (CL) TH-3 14 14.4 118 0.6 1,800 3,600 CLAY, SANDY (CL) SWELL TEST RESULTS* TABLE A-I SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS Page 1 of 1 * NEGATIVE VALUE INDICATES COMPRESSION. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL|T PROJECT NO. FC08890-125 APPENDIX B SAMPLE SITE GRADING SPECIFICATIONS DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 B-1 SAMPLE SITE GRADING SPECIFICATIONS 1. DESCRIPTION This item shall consist of the excavation, transportation, placement and compac- tion of materials from locations indicated on the plans, or staked by the Engineer, as necessary to achieve building site elevations. 2. GENERAL The Geotechnical Engineer shall be the Owner's representative. The Geotech- nical Engineer shall approve fill materials, method of placement, moisture con- tents and percent compaction, and shall give written approval of the completed fill. 3. CLEARING JOB SITE The Contractor shall remove all trees, brush and rubbish before excavation or fill placement is begun. The Contractor shall dispose of the cleared material to pro- vide the Owner with a clean, neat appearing job site. Cleared material shall not be placed in areas to receive fill or where the material will support structures of any kind. 4. SCARIFYING AREA TO BE FILLED All topsoil and vegetable matter shall be removed from the ground surface upon which fill is to be placed. The surface shall then be plowed or scarified to a depth of 8 inches until the surface is free from ruts, hummocks or other uneven fea- tures, which would prevent uniform compaction by the equipment to be used. 5. COMPACTING AREA TO BE FILLED After the foundation for the fill has been cleared and scarified, it shall be disked or bladed until it is free from large clods, brought to the proper moisture content and compacted to not less than 95 percent of maximum dry density as deter- mined in accordance with ASTM D 698 or AASHTO T 99. 6. FILL MATERIALS On-site materials classifying as CL, SC, SM, SW, SP, GP, GC and GM are ac- ceptable. Fill soils shall be free from organic matter, debris, or other deleterious substances, and shall not contain rocks or lumps having a diameter greater than three (3) inches. Fill materials shall be obtained from the existing fill and other approved sources. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 B-2 7. MOISTURE CONTENT Fill materials shall be moisture treated. Clay soils placed below the building en- velope should be moisture-treated to between 1 and 4 percent above optimum moisture content as determined from Standard Proctor compaction tests. Clay soil placed exterior to the building should be moisture treated between optimum and 3 percent above optimum moisture content. Sand soils can be moistened to within 2 percent of optimum moisture content. Sufficient laboratory compaction tests shall be performed to determine the optimum moisture content for the vari- ous soils encountered in borrow areas. The Contractor may be required to add moisture to the excavation materials in the borrow area if, in the opinion of the Geotechnical Engineer, it is not possible to obtain uniform moisture content by adding water on the fill surface. The Con- tractor may be required to rake or disk the fill soils to provide uniform moisture content through the soils. The application of water to embankment materials shall be made with any type of watering equipment approved by the Geotechnical Engineer, which will give the desired results. Water jets from the spreader shall not be directed at the em- bankment with such force that fill materials are washed out. Should too much water be added to any part of the fill, such that the material is too wet to permit the desired compaction from being obtained, rolling and all work on that section of the fill shall be delayed until the material has been allowed to dry to the required moisture content. The Contractor will be permitted to rework wet material in an approved manner to hasten its drying. 8. COMPACTION OF FILL AREAS Selected fill material shall be placed and mixed in evenly spread layers. After each fill layer has been placed, it shall be uniformly compacted to not less than the specified percentage of maximum dry density. Fill materials shall be placed such that the thickness of loose material does not exceed 8 inches and the com- pacted lift thickness does not exceed 6 inches. Compaction, as specified above, shall be obtained by the use of sheepsfoot roll- ers, multiple-wheel pneumatic-tired rollers, or other equipment approved by the Engineer. Compaction shall be accomplished while the fill material is at the specified moisture content. Compaction of each layer shall be continuous over the entire area. Compaction equipment shall make sufficient trips to insure that the required dry density is obtained. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 B-3 9. COMPACTION OF SLOPES Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction operations shall be continued until slopes are stable, but not too dense for planting, and there is no appreciable amount of loose soil on the slopes. Compaction of slopes may be done progressively in increments of three to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent fill slopes shall not exceed 3:1 (horizontal to vertical). 10. DENSITY TESTS Field density tests shall be made by the Geotechnical Engineer at locations and depths of his choosing. Where sheepsfoot rollers are used, the soil may be dis- turbed to a depth of several inches. Density tests shall be taken in compacted material below the disturbed surface. When density tests indicate that the dry density or moisture content of any layer of fill or portion thereof is below that re- quired, the particular layer or portion shall be reworked until the required dry den- sity or moisture content has been achieved. 11. COMPLETED PRELIMINARY GRADES All areas, both cut and fill, shall be finished to a level surface and shall meet the following limits of construction: A. Overlot cut or fill areas shall be within plus or minus 2/10 of one foot. B. Street grading shall be within plus or minus 1/10 of one foot. The civil engineer, or duly authorized representative, shall check all cut and fill areas to observe that the work is in accordance with the above limits. 12. SUPERVISION AND CONSTRUCTION STAKING Observation by the Geotechnical Engineer shall be continuous during the place- ment of fill and compaction operations so that he can declare that the fill was placed in general conformance with specifications. All site visits necessary to test the placement of fill and observe compaction operations will be at the ex- pense of the Owner. All construction staking will be provided by the Civil Engi- neer or his duly authorized representative. Initial and final grading staking shall be at the expense of the owner. The replacement of grade stakes through con- struction shall be at the expense of the contractor. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 B-4 13. SEASONAL LIMITS No fill material shall be placed, spread or rolled while it is frozen, thawing, or dur- ing unfavorable weather conditions. When work is interrupted by heavy precipi- tation, fill operations shall not be resumed until the Geotechnical Engineer indi- cates that the moisture content and dry density of previously placed materials are as specified. 14. NOTICE REGARDING START OF GRADING The contractor shall submit notification to the Geotechnical Engineer and Owner advising them of the start of grading operations at least three (3) days in advance of the starting date. Notification shall also be submitted at least 3 days in ad- vance of any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 15. REPORTING OF FIELD DENSITY TESTS Density tests performed by the Geotechnical Engineer, as specified under "Den- sity Tests" above, shall be submitted progressively to the Owner. Dry density, moisture content and percent compaction shall be reported for each test taken. 16. DECLARATION REGARDING COMPLETED FILL The Geotechnical Engineer shall provide a written declaration stating that the site was filled with acceptable materials, or was placed in general accordance with the specifications. APPENDIX C PAVEMENT CONSTRUCTION RECOMMENDATIONS DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 C-1 SUBGRADE PREPARATION Moisture Treated Subgrade (MTS) 1. The subgrade should be stripped of organic matter, scarified, mois- ture treated and compacted to the specifications stated below in Item 2. The compacted subgrade should extend at least 3 feet be- yond the edge of the pavement where no edge support, such as curb and gutter, are to be constructed. 2. Sandy and gravelly soils (A-1-a, A-1-b, A-3, A-2-4, A-2-5, A-2-6, A- 2-7) should be moisture conditioned near optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698, AASHTO T 99). Clayey soils (A-6, A-7-5, A-7-6) should be moisture conditioned between optimum and 3 per- cent above optimum moisture content and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698, AASHTO T 99). 3. Utility trenches and all subsequently placed fill should be properly compacted and tested prior to paving. As a minimum, fill should be compacted to 95 percent of standard Proctor maximum dry density. 4. Final grading of the subgrade should be carefully controlled so the design cross-slope is maintained and low spots in the subgrade that could trap water are eliminated. 5. Once final subgrade elevation has been compacted and tested to compliance and shaped to the required cross-section, the area should be proof-rolled using a minimum axle load of 18 kips per axle. The proof-roll should be performed while moisture contents of the subgrade are still within the recommended limits. Drying of the subgrade prior to proof-roll or paving should be avoided. 6. Areas that are observed by the Engineer that have soft spots in the subgrade, or where deflection is not uniform of soft or wet subgrade shall be ripped, scarified, dried or wetted as necessary and recom- pacted to the requirements for the density and moisture. As an al- ternative, those areas may be sub-excavated and replaced with properly compacted structural backfill. Where extensively soft, yielding subgrade is encountered; we recommend a representative of our office observe the excavation. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 C-2 PAVEMENT MATERIALS AND CONSTRUCTION Aggregate Base Course (ABC) 1. A Class 5 or 6 Colorado Department of Transportation (CDOT) specified ABC should be used. A reclaimed concrete pavement (RCP) alternative which meets the Class 5 or 6 designation and de- sign R-value/strength coefficient is also acceptable. Blending of re- cycled products with ABC may be considered. 2. Bases should have a minimum Hveem stabilometer value of 72, or greater. ABC, RAP, RCP, or blended materials must be moisture stable. The change in R-value from 300-psi to 100-psi exudation pressure should be 12 points or less. 3. ABC or RCP bases should be placed in thin lifts not to exceed 6 inches and moisture treated to near optimum moisture content. Ba- ses should be moisture treated to near optimum moisture content, and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D 698, AASHTO T 99). 4. Placement and compaction of ABC or RCP should be observed and tested by a representative of our firm. Placement should not com- mence until the underlying subgrade is properly prepared and tested. Hot Mix Asphalt (HMA) 1. HMA should be composed of a mixture of aggregate, filler, hydrated lime, and asphalt cement. Some mixes may require polymer modi- fied asphalt cement, or make use of up to 20 percent reclaimed as- phalt pavement (RAP). A job mix design is recommended and peri- odic checks on the job site should be made to verify compliance with specifications. 2. HMA should be relatively impermeable to moisture and should be designed with crushed aggregates that have a minimum of 80 per- cent of the aggregate retained on the No. 4 sieve with two mechani- cally fractured faces. 3. Gradations that approach the maximum density line (within 5 per- cent between the No. 4 and 50 sieves) should be avoided. A gra- dation with a nominal maximum size of 1 or 2 inches developed on the fine side of the maximum density line should be used. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 C-3 4. Total void content, voids in the mineral aggregate (VMA) and voids filled should be considered in the selection of the optimum asphalt cement content. The optimum asphalt content should be selected at a total air void content of approximately 4 percent. The mixture should have a minimum VMA of 14 percent and between 65 per- cent and 80 percent of voids filled. 5. Asphalt cement should meet the requirements of the Superpave Performance Graded (PG) Binders. The minimum performing as- phalt cement should conform to the requirements of the governing agency. 6. Hydrated lime should be added at the rate of 1 percent by dry weight of the aggregate and should be included in the amount pass- ing the No. 200 sieve. Hydrated lime for aggregate pretreatment should conform to the requirements of ASTM C 207, Type N. 7. Paving should be performed on properly prepared, unfrozen sur- faces that are free of water, snow and ice. Paving should only be performed when both air and surface temperatures equal, or ex- ceed, the temperatures specified in Table 401-3 of the 2006 Colo- rado Department of Transportation Standard Specifications for Road and Bridge Construction. 8. HMA should not be placed at a temperature lower than 245o F for mixes containing PG 64-22 asphalt, and 290o F for mixes containing polymer-modified asphalt. The breakdown compaction should be completed before the HMA temperature drops 20o F. 9. Wearing surface course shall be Grading S or SX for residential roadway classifications and Grading S for collector, arterial, indus- trial, and commercial roadway classifications. 10. The minimum/maximum lift thicknesses for Grade SX shall be 1½ inches/2½ inches. The minimum/maximum lift thicknesses for Grade S shall be 2 inches/3½ inches. The minimum/maximum lift thicknesses for Grade SG shall be 3 inches/5 inches. 11. Joints should be staggered. No joints should be placed within wheel paths. 12. HMA should be compacted to between 92 and 96 percent of Maxi- mum Theoretical Density. The surface shall be sealed with a finish roller prior to the mix cooling to 185o F. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 C-4 13. Placement and compaction of HMA should be observed and tested by a representative of our firm. Placement should not commence until approval of the proof rolling as discussed in the Subgrade Preparation section of this report. Sub base, base course or initial pavement course shall be placed within 48 hours of approval of the proof rolling. If the Contractor fails to place the sub base, base course or initial pavement course within 48 hours or the condition of the subgrade changes due to weather or other conditions, proof roll- ing and correction shall be performed again. Portland Cement Concrete (PCC) 1. Portland cement concrete should consist of Class P of the 2011 CDOT - Standard Specifications for Road and Bridge Construction specifications for normal placement or Class E for fast-track pro- jects. PCC should have a minimum compressive strength of 4,200 psi at 28 days and a minimum modulus of rupture (flexural strength) of 650 psi. Job mix designs are recommended and periodic checks on the job site should be made to verify compliance with specifica- tions. 2. Portland cement should be Type II “low alkali” and should conform to ASTM C 150. 3. Portland cement concrete should not be placed when the subgrade or air temperature is below 40°F. 4. Concrete should not be placed during warm weather if the mixed concrete has a temperature of 90°F, or higher. 5. Mixed concrete temperature placed during cold weather should have a temperature between 50°F and 90°F. 6. Free water should not be finished into the concrete surface. Atom- izing nozzle pressure sprayers for applying finishing compounds are recommended whenever the concrete surface becomes difficult to finish. 7. Curing of the portland cement concrete should be accomplished by the use of a curing compound. The curing compound should be applied in accordance with manufacturer recommendations. 8. Curing procedures should be implemented, as necessary, to pro- tect the pavement against moisture loss, rapid temperature change, freezing, and mechanical injury. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 C-5 9. Construction joints, including longitudinal joints and transverse joints, should be formed during construction or sawed after the con- crete has begun to set, but prior to uncontrolled cracking. 10. All joints should be properly sealed using a rod back-up and ap- proved epoxy sealant. 11. Traffic should not be allowed on the pavement until it has properly cured and achieved at least 80 percent of the design strength, with saw joints already cut. 12. Placement of portland cement concrete should be observed and tested by a representative of our firm. Placement should not com- mence until the subgrade is properly prepared and tested. APPENDIX D PAVEMENT MAINTENANCE PROGRAM DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 D-1 MAINTENANCE RECOMMENDATIONS FOR FLEXIBLE PAVEMENTS A primary cause for deterioration of pavements is oxidative aging resulting in brittle pavements. Tire loads from traffic are necessary to "work" or knead the asphalt concrete to keep it flexible and rejuvenated. Preventive maintenance treatments will typically preserve the original or existing pavement by providing a protective seal or rejuvenating the asphalt binder to extend pavement life. 1. Annual Preventive Maintenance a. Visual pavement evaluations should be performed each spring or fall. b. Reports documenting the progress of distress should be kept current to provide information on effective times to apply pre- ventive maintenance treatments. c. Crack sealing should be performed annually as new cracks ap- pear. 2. 3 to 5 Year Preventive Maintenance a. The owner should budget for a preventive treatment at approxi- mate intervals of 3 to 5 years to reduce oxidative embrittlement problems. b. Typical preventive maintenance treatments include chip seals, fog seals, slurry seals and crack sealing. 3. 5 to 10 Year Corrective Maintenance a. Corrective maintenance may be necessary, as dictated by the pavement condition, to correct rutting, cracking and structurally failed areas. b. Corrective maintenance may include full depth patching, milling and overlays. c. In order for the pavement to provide a 20-year service life, at least one major corrective overlay should be expected. DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTLT PROJECT NO. FC08890-125 D-2 MAINTENANCE RECOMMENDATIONS FOR RIGID PAVEMENTS High traffic volumes create pavement rutting and smooth polished sur- faces. Preventive maintenance treatments will typically preserve the original or existing pavement by providing a protective seal and improving skid resistance through a new wearing course. 1. Annual Preventive Maintenance a. Visual pavement evaluations should be performed each spring or fall. b. Reports documenting the progress of distress should be kept current to provide information of effective times to apply preven- tive maintenance. c. Crack sealing should be performed annually as new cracks ap- pear. 2. 4 to 8 Year Preventive Maintenance a. The owner should budget for a preventive treatment at approxi- mate intervals of 4 to 8 years to reduce joint deterioration. b. Typical preventive maintenance for rigid pavements includes patching, crack sealing and joint cleaning and sealing. c. Where joint sealants are missing or distressed, resealing is mandatory. 3. 15 to 20 Year Corrective Maintenance a. Corrective maintenance for rigid pavements includes patching and slab replacement to correct subgrade failures, edge dam- age, and material failure. b. Asphalt concrete overlays may be required at 15 to 20 year in- tervals to improve the structural capacity of the pavement. 20 30 40 50 60 70 80 90 100 CLAY (PLASTIC) TO SILT (NON-PLASTIC) SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES DIAMETER OF PARTICLE IN MILLIMETERS 25 HR. 7 HR. HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS PERCENT PASSING 0 10 20 30 50 60 70 80 90 100 PERCENT RETAINED 40 0.002 15 MIN. .005 60 MIN. .009 19 MIN. .019 4 MIN. .037 1 MIN. .074 *200 .149 *100 .297 *50 0.42 *40 .590 *30 1.19 *16 2.0 *10 2.38 *8 4.76 *4 9.52 3/8" 19.1 3/4" 36.1 1½" 76.2 3" 127 5" 152 6" 200 8" .001 45 MIN. 0 10 20 30 40 50 60 70 80 90 100 CLAY (PLASTIC) TO SILT (NON-PLASTIC) SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES DIAMETER OF PARTICLE IN MILLIMETERS 25 HR. 7 HR. HYDROMETER ANALYSIS SIEVE ANALYSIS TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS PERCENT PASSING PERCENT RETAINED 0 10 20 30 40 50 60 70 80 90 100 - - INDICATES MOISTURE CONTENT (%). INDICATES DRY DENSITY (PCF). INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%). INDICATES PASSING NO. 200 SIEVE (%). INDICATES LIQUID LIMIT. INDICATES PLASTICITY INDEX. INDICATES UNCONFINED COMPRESSIVE STRENGTH (PSF). INDICATES SOLUBLE SULFATE CONTENT (%). DITESCO PROJECT AND CONSTRUCTION SERVICES TIMBERLINE CENTER CTL | T PROJECT NO. FC08890-125 5/12 8/12 8/12 50/9 WC=10.4 DD=102 SW=0.0 SS=<0.01 WC=13.9 DD=119 SW=0.1 WC=10.4 DD=102 SW=0.0 SS=<0.01 WC=13.9 DD=119 SW=0.1 TH-1 El. 98.5 7/12 12/12 18/12 12/12 50/11 WC=16.7 DD=111 SW=0.2 SS=<0.01 WC=18.1 DD=107 SW=0.0 WC=16.7 DD=111 SW=0.2 SS=<0.01 WC=18.1 DD=107 SW=0.0 TH-2 El. 98.5 12/12 25/12 21/12 50/9 50/12 50/3 WC=7.0 DD=110 SW=2.3 WC=15.1 DD=115 LL=40 PI=25 -200=82 WC=14.4 DD=118 SW=0.6 WC=7.0 DD=110 SW=2.3 WC=15.1 DD=115 LL=40 PI=25 -200=82 WC=14.4 DD=118 SW=0.6 TH-3 El. 99.5