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HomeMy WebLinkAboutVILLAGE ON HORSETOOTH (AFFORDABLE HOUSING) - PDP - PDP160025 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT400 North Link Lane | Fort Collins, Colorado 80524 Telephone: 970-206-9455 Fax: 970-206-9441 GEOTECHNICAL INVESTIGATION FCHA VILLAGE AT HORSETOOTH 1506 WEST HORESTOOTH ROAD FORT COLLINS, COLORADO FORT COLLINS HOUSING AUTHORITY 1715 West Mountain Avenue Fort Collins, Colorado 80521 Attention: Kristin Fritz, AICP Project No. FC07464-120 July 19, 2016 FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE CONDITIONS AND PROPOSED CONSTRUCTION 2 INVESTIGATION 2 SUBSURFACE CONDITIONS 3 SEISMICITY 3 SITE DEVELOPMENT 4 Fill Placement 4 Excavations 5 FOUNDATIONS 5 Spread Footings 5 BELOW GRADE AREAS 6 FLOOR SYSTEMS 6 PAVEMENTS 9 Pavement Selection 10 Subgrade and Pavement Materials and Construction 10 Pavement Maintenance 10 WATER-SOLUBLE SULFATES 11 SURFACE DRAINAGE 11 GEOTECHNICAL RISK 11 LIMITATIONS 12 FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS FIGURES 2 AND 3 – 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 FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 1 SCOPE This report presents the results of our Geotechnical Investigation for the proposed FCHA Village at Horsetooth in Fort Collins, Colorado. The purpose of the investigation was to evaluate the subsurface conditions and provide founda- tion recommendations and geotechnical design criteria for the project. 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 explorato- ry 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, lateral earth loads, pavements and drainage are provided. If the pro- posed construction changes, we should be requested to review our recommen- dations. Our conclusions are summarized in the following paragraphs. SUMMARY OF CONCLUSIONS 1. Soils encountered in our borings consisted of interlayered sandy clay and clayey sand to the depths explored. Based on laboratory testing, the soils are generally non-expansive to low-swelling. No bedrock was encountered in our borings. 2. Groundwater was encountered at depths of 19 to 23 feet during drilling and was measured several days after drilling at depths of 19 to 22 feet. Existing groundwater levels are not expected to signifi- cantly affect the proposed construction. 3. We believe the proposed structures can be constructed on a spread footing foundation placed on natural, undisturbed soil and/or properly compacted fill. Foundation design and construction rec- ommendations are presented in this report. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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 will generally consist of A-4 and A- 2-4 materials according to AASHTO criteria, with expected poor to good subgrade support. Recommended section thicknesses and pavement materials are provided in this report. SITE CONDITIONS AND PROPOSED CONSTRUCTION The area of proposed development is on the north side of Horsetooth Road east of Big Ben Drive in Fort Collins, Colorado. An existing residence with horse stalls and associated pasture areas were located on site at the time of our investigation. The ground surface is generally flat; vegetation consisted of natural grasses, weeds and trees. A ditch runs along the eastern boundary of the proper- ty. We understand that the proposed construction will consist of nine apart- ment buildings having 96 units, a club house, and associated paved parking are- as and access drives. No below grade areas are planned. INVESTIGATION Subsurface conditions were investigated by drilling thirteen exploratory borings to depths of approximately 20 to 30 feet. Our representative observed drilling operations, logged the soil found in the borings, and obtained samples. Groundwater measurements were taken during and several days after drilling. Summary logs of the borings, including results of field penetration resistance tests, are presented on Figures 2 and 3. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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, gradation, Atterberg limits, and water-soluble sulfate tests. Results of laboratory tests are presented in Appendix A and summarized in Table A-I. SUBSURFACE CONDITIONS Soils encountered in our borings consisted of interlayered sandy clay and clayey sand to the depths explored. The soils classified as loose to medium dense / medium stiff to very stiff based on field penetration test results. Swell- consolidation testing was conducted on 26 samples; results indicated 3 percent compression to 1.7 percent swell. Groundwater was encountered at depths of 19 to 23 feet during drilling and was measured several days after drilling at depths of 19 to 22 feet. Existing groundwater levels are not expected to significantly affect the proposed construc- tion. SEISMICITY This area, like most of central Colorado, is subject to a low degree of seismic 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 conditions encountered in our borings, this site probably classifies as a Site Class D. Only minor damage to relatively new, properly designed and built build- ings would be expected. Wind loads, not seismic considerations, typically govern dynamic structural design in this area. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 4 SITE DEVELOPMENT Fill Placement The existing onsite soils are suitable for re-use as fill material provided debris 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, AASH- TO T99). Sand soils used as fill should be moistened to within 2 percent of opti- mum moisture content. Clay soils should be moistened between optimum and 3 percent above optimum moisture content. The fill should be moisture- conditioned, placed in thin, loose lifts (8 inches or less) and compacted as de- scribed above. We should observe placement and compaction of fill during con- struction. Fill placement and compaction should not be conducted when the fill material is frozen. 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 effect 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 5 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 refers to OSHA standards to determine ap- propriate 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. FOUNDATIONS Our investigation indicates low swelling or non-expansive soils are present at the anticipated foundation levels. Spread footing foundations are considered appropriate for the conditions encountered. Design criteria for spread footing foundations developed from analysis of field and laboratory data and our experi- ence are presented below. Spread Footings 1. Footings should be constructed on undisturbed natural soils or properly compacted fill (see the Fill Placement section of this re- port). Where soil is loosened during excavation, it should be re- moved and replaced with on-site soils compacted following the cri- teria in the Fill Placement section of this report. Footings should bear completely on one material type. 2. Footings constructed on the natural soils and/or engineered fill can be designed for a net allowable soil pressure of 2,000 pounds per square foot (psf). The soil pressure can be increased 33 percent for transient loads such as wind or seismic loads. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 6 3. Footings should have a minimum width of at least 16 inches. Foundations for isolated columns should have minimum dimen- sions of 18 inches by 18 inches. Larger sizes may be required de- pending on loads and the structural system used. 4. The soils beneath footing pads can be assigned an ultimate coeffi- cient of friction of 0.5 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. BELOW GRADE AREAS No below grade areas are planned for the buildings. For this condition, perimeter drains are not usually necessary. We should be contacted to provide foundation 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. 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 7 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 8 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 rec- ommend a modulus of subgrade reaction of 50 pci for on-site soils. 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 2009 and 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 beneficial below concrete slab-on-grade floors where floor FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 8 coverings, painted floor surfaces or products stored on the floor will be sensitive to moisture. The vapor retarder is most effective when concrete 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 flex- ible couplings. Pressurized water supply lines should be brought above the floors as quickly as possible. 5. Plumbing and utilities that pass through the slabs should be isolat- ed 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 9 PAVEMENTS The project will include a paved parking lot and access drives. The per- formance of a pavement structure is dependent upon the characteristics of the subgrade soil, traffic loading and frequency, climatic conditions, drainage and pavement materials. Subgrade soils at this site generally classify as AASHTO Group A-2-4 or Group A-4 with expected poor to good subgrade support. If fill is needed, we have assumed it will be soils with similar or better characteristics. Traffic loading of a parking lot can be estimated based on type of usage and number of parking spaces. Delivery and garbage truck traffic is anticipated to be minor and possibly isolated to certain areas of the parking lot. We understand 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 experience. Using the criteria discussed above we recommend the minimum pavement sections provided in Table A. TABLE A RECOMMENDED PAVEMENT SECTIONS Classification Hot Mix Asphalt (HMA) + Aggregate Base Course (ABC) Portland Cement Concrete (PCC) + Moisture Treated Subgrade Parking Area 4" HMA + 6" ABC 6" PCC Access Drives / Heavy Traffic Areas 5" HMA + 6" ABC 6" PCC Trash Enclosures - 6" PCC FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 10 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 expected to perform well in these areas. PCC pave- ment also 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. 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 destroy the integrity of the pavement and result in a severe decrease in service- ability. To restore the pavement top original serviceability, careful backfill com- paction before repaving is necessary. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 11 WATER-SOLUBLE SULFATES Concrete that comes into contact with soils can be subject to sulfate at- tack. We measured water-soluble sulfate concentrations in four samples from this site. Concentrations measured were 0.05 percent or less. Sulfate concen- trations less than 0.1 percent indicate Class 0 exposure to sulfate attack for con- crete that comes into contact with the subsoils, according to the American Con- crete Institute (ACI). For this level of sulfate concentration, ACI indicates any type of cement can be used for concrete that comes into contact with the soils and/or bedrock. 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. 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. GEOTECHNICAL RISK The concept of risk is an important aspect of any geotechnical evaluation primarily because the methods used to develop geotechnical recommendations do not comprise an exact science. We never have complete knowledge of sub- FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 12 surface conditions. Our analysis must be tempered with engineering judgment and experience. Therefore, the recommendations presented in any geotechnical evaluation should not be considered risk-free. Our recommendations represent our judgment of those measures that are necessary to increase the chances that the structures will perform satisfactorily. It is critical that all recommendations in this report are followed during construction. Property owners must assume re- sponsibility for maintaining the structures and use appropriate practices regard- ing drainage and landscaping. Improvements performed after construction, such as construction of additions, retaining walls, decks, patios, landscaping and exte- rior flatwork, should be completed in accordance with recommendations in this report. 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 TH-2 TH-3 TH-4 TH-10 TH-11 TH-12 TH-13 TH-5 TH-7 TH-6 TH-9 TH-8 West Horsetooth Road TAFT HILL RD. SHIELDS ST. HORSETOOTH RD. BIG BEN DR. SITE LEGEND: INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING TH-1 FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL I T PROJECT NO. FC07464-120 FIGURE 1 Locations of Exploratory Borings VICINITY MAP (FORT COLLINS, COLORADO) NOT TO SCALE 100' APPROXIMATE SCALE: 1" = 100' 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 10/12 28/12 12/12 9/12 WC=12.3 DD=109 SW=-0.2 WC=11.2 DD=115 SW=0.7 SS=0.050 WC=12.3 DD=109 SW=-0.2 WC=11.2 DD=115 SW=0.7 SS=0.050 TH-1 10/12 11/12 16/12 10/12 11/12 WC=4.7 DD=117 LL=24 PI=9 -200=32 WC=5.1 DD=105 SW=-1.2 WC=6.5 DD=111 -200=41 WC=4.7 DD=117 LL=24 PI=9 -200=32 WC=5.1 DD=105 SW=-1.2 WC=6.5 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 10/12 15/12 9/12 9/12 WC=8.3 DD=124 SW=0.2 WC=11.4 DD=123 SW=0.1 WC=8.3 DD=124 SW=0.2 WC=11.4 DD=123 SW=0.1 TH-7 15/12 7/12 8/12 9/12 9/12 WC=4.6 DD=123 SW=0.4 WC=7.4 DD=115 SW=1.7 WC=8.2 DD=124 SW=0.0 WC=14.1 DD=116 SW=-0.1 WC=4.6 DD=123 SW=0.4 WC=7.4 DD=115 SW=1.7 WC=8.2 DD=124 APPENDIX A RESULTS OF LABORATORY TESTING Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 109 PCF From TH - 1 AT 4 FEET MOISTURE CONTENT= 12.3 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 115 PCF From TH - 1 AT 9 FEET MOISTURE CONTENT= 11.2 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-1 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION 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 SAND, CLAYEY (SC) DRY UNIT WEIGHT= 105 PCF From TH - 2 AT 9 FEET MOISTURE CONTENT= 5.1 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 123 PCF From TH - 3 AT 4 FEET MOISTURE CONTENT= 8.7 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-2 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION 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 SAND, CLAYEY (SC) DRY UNIT WEIGHT= 118 PCF From TH - 4 AT 4 FEET MOISTURE CONTENT= 12.9 % Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 118 PCF From TH - 4 AT 14 FEET MOISTURE CONTENT= 9.9 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-3 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 99 PCF From TH - 5 AT 4 FEET MOISTURE CONTENT= 4.0 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 122 PCF From TH - 5 AT 9 FEET MOISTURE CONTENT= 7.9 % Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 112 PCF From TH - 5 AT 14 FEET MOISTURE CONTENT= 6.0 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-5 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 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 107 PCF From TH - 5 AT 19 FEET MOISTURE CONTENT= 11.2 % Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 123 PCF From TH - 6 AT 4 FEET MOISTURE CONTENT= 11.5 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-6 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION 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 SAND, CLAYEY (SC) DRY UNIT WEIGHT= 126 PCF From TH - 6 AT 9 FEET MOISTURE CONTENT= 8.4 % Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 124 PCF From TH - 7 AT 4 FEET MOISTURE CONTENT= 8.3 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-7 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= 123 PCF From TH - 7 AT 9 FEET MOISTURE CONTENT= 11.4 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 123 PCF From TH - 8 AT 4 FEET MOISTURE CONTENT= 4.6 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-8 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 SAND, CLAYEY (SC) DRY UNIT WEIGHT= 115 PCF From TH - 8 AT 9 FEET MOISTURE CONTENT= 7.4 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 124 PCF From TH - 8 AT 14 FEET MOISTURE CONTENT= 8.2 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-9 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 NO MOVEMENT DUE TO WETTING 0.1 1.0 10 100 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 116 PCF From TH - 8 AT 19 FEET MOISTURE CONTENT= 14.1 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 120 PCF From TH - 9 AT 4 FEET MOISTURE CONTENT= 5.1 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-10 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION 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= 121 PCF From TH - 10 AT 9 FEET MOISTURE CONTENT= 11.3 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 131 PCF From TH - 11 AT 4 FEET MOISTURE CONTENT= 8.4 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-11 COMPRESSION % EXPANSION -4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION 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 SAND, CLAYEY (SC) DRY UNIT WEIGHT= 116 PCF From TH - 11 AT 19 FEET MOISTURE CONTENT= 15.7 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-12 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 127 PCF From TH - 12 AT 4 FEET MOISTURE CONTENT= 9.0 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= PCF From TH - 12 AT 9 FEET MOISTURE CONTENT= 2.2 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation FIGURE A-13 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 SAND, CLAYEY (SC) DRY UNIT WEIGHT= 115 PCF From TH - 13 AT 9 FEET MOISTURE CONTENT= 9.2 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-14 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) DRY UNIT WEIGHT= 121 PCF From TH - 13 AT 19 FEET MOISTURE CONTENT= 12.9 % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-15 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of SAND, CLAYEY (SC) GRAVEL 4 % SAND 55 % From TH - 2 AT 14 FEET SILT & CLAY 41 % LIQUID LIMIT % PLASTICITY INDEX % Sample of SAND, SLIGHTLY CLAYEY, GRAVELLY (SP-SC) GRAVEL 15 % SAND 74 % From TH - 9 AT 14 FEET SILT & CLAY 11 % LIQUID LIMIT % PLASTICITY INDEX % FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 FIGURE A-16 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 NO. 200 SOLUBLE DEPTH CONTENT DENSITY LIMIT INDEX SWELL* PRESSURE SIEVE SULFATES BORING (FEET) (%) (PCF) (%) (PSF) (%) (%) DESCRIPTION TH-1 4 12.3 109 -0.2 500 SAND, CLAYEY (SC) TH-1 9 11.2 115 0.7 1,100 0.05 CLAY, SANDY (CL) TH-2 4 4.7 117 24 9 32 SAND, CLAYEY (SC) TH-2 9 5.1 105 -1.2 1,100 SAND, CLAYEY (SC) TH-2 14 6.5 111 41 SAND, CLAYEY (SC) TH-3 4 8.7 123 1.0 500 CLAY, SANDY (CL) TH-3 9 2.5 20 SAND, CLAYEY (SC) TH-4 4 12.9 118 -0.1 500 SAND, CLAYEY (SC) TH-4 14 9.9 118 -0.1 1,800 SAND, CLAYEY (SC) TH-5 4 4.0 99 -3.0 500 SAND, CLAYEY (SC) TH-5 9 7.9 122 0.1 1,100 SAND, CLAYEY (SC) TH-5 14 6.0 112 -0.3 1,800 SAND, CLAYEY (SC) TH-5 19 11.2 107 -0.1 2,400 SAND, CLAYEY (SC) TH-6 4 11.5 123 0.5 500 0.01 SAND, CLAYEY (SC) TH-6 9 8.4 126 0.3 1,100 SAND, CLAYEY (SC) TH-7 4 8.3 124 0.2 500 SAND, CLAYEY (SC) TH-7 9 11.4 123 0.1 1,100 CLAY, SANDY (CL) TH-8 4 4.6 123 0.4 500 CLAY, SANDY (CL) TH-8 9 7.4 115 1.7 1,100 SAND, CLAYEY (SC) TH-8 14 8.2 124 0.0 1,800 CLAY, SANDY (CL) TH-8 19 14.1 116 -0.1 2,400 CLAY, SANDY (CL) TH-9 4 5.1 120 1.0 500 0.01 CLAY, SANDY (CL) TH-9 14 1.7 11 SAND, SLIGHTLY CLAYEY, GRAVELLY (SP-SC) TH-10 4 10.6 123 14 NP 61 SILT, SANDY (ML) TH-10 9 11.3 121 -0.1 1,100 CLAY, SANDY (CL) TH-11 4 8.4 131 1.4 500 CLAY, SANDY (CL) TH-11 19 15.7 116 -0.1 2,400 SAND, CLAYEY (SC) TH-12 4 9.0 127 1.1 500 CLAY, SANDY (CL) TH-12 9 2.2 1.4 1,100 <0.01 CLAY, SANDY (CL) TH-13 9 9.2 115 -1.1 1,100 SAND, CLAYEY (SC) TH-13 19 12.9 121 -0.2 2,400 SAND, CLAYEY (SC) SWELL TEST RESULTS* TABLE A-I SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS Page 1 of 1 * NEGATIVE VALUE INDICATES COMPRESSION. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL|T PROJECT NO. FC07464-120 APPENDIX B SAMPLE SITE GRADING SPECIFICATIONS FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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 density 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. 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- FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 B-4 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 FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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 ax- le. 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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 design R-value/strength coefficient is also acceptable. Blending of recycled 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. Bases should be moisture treated to near optimum moisture con- tent, and compacted to at least 95 percent of standard Proctor max- imum 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 test- ed. 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 pe- riodic 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 mechan- ically 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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 245 o F for mixes containing PG 64-22 asphalt, and 290 o F for mixes containing polymer-modified asphalt. The breakdown compaction should be completed before the HMA temperature drops 20 o 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 185 o F. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 C-5 9. Construction joints, including longitudinal joints and transverse joints, should be formed during construction or sawed after the concrete 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 FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 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. FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-120 D-2 MAINTENANCE RECOMMENDATIONS FOR RIGID PAVEMENTS High traffic volumes create pavement rutting and smooth polished surfac- es. Preventive maintenance treatments will typically preserve the original or ex- isting 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 SW=0.0 WC=14.1 DD=116 SW=-0.1 TH-8 25/12 39/12 24/12 10/12 16/12 WC=5.1 DD=120 SW=1.0 SS=0.010 WC=1.7 -200=11 WC=5.1 DD=120 SW=1.0 SS=0.010 WC=1.7 -200=11 TH-9 17/12 7/12 16/12 11/12 WC=10.6 DD=123 LL=14 PI=NP -200=61 WC=11.3 DD=121 SW=-0.1 WC=10.6 DD=123 LL=14 PI=NP -200=61 WC=11.3 DD=121 SW=-0.1 TH-10 16/12 11/12 13/12 11/12 16/12 WC=8.4 DD=131 SW=1.4 WC=15.7 DD=116 SW=-0.1 WC=8.4 DD=131 SW=1.4 WC=15.7 DD=116 SW=-0.1 TH-11 19/12 24/12 11/12 10/12 12/12 11/12 WC=9.0 DD=127 SW=1.1 WC=2.2 SW=1.4 SS=<0.01 WC=9.0 DD=127 SW=1.1 WC=2.2 SW=1.4 SS=<0.01 TH-12 21/12 12/12 9/12 12/12 WC=9.2 DD=115 SW=-1.1 WC=12.9 DD=121 SW=-0.2 WC=9.2 DD=115 SW=-1.1 WC=12.9 DD=121 SW=-0.2 TH-13 DEPTH - FEET 2. DRIVE SAMPLE. THE SYMBOL 10/12 INDICATES 10 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. SAND, CLAYEY WITH LAYERS OF CLAY AND SILT, MOIST TO WET, LOOSE TO DENSE AND STIFF TO VERY STIFF, BROWN, REDDISH BROWN (SP, SC, CL) 1. NOTES: WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. CLAY, SANDY, MOIST, STIFF TO VERY STIFF, REDDISH BROWN (CL) 3. LEGEND: DEPTH - FEET WATER LEVEL MEASURED AT TIME OF DRILLING. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. Summary Logs of Exploratory Borings THE BORINGS WERE DRILLED ON JUNE 16, 2016, USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. FIGURE 3 WC DD SW -200 LL PI UC SS - - - - - - - - INDICATES DEPTH WHERE HOLE CAVED PRIOR TO SECONDARY GROUNDWATER MEASUREMENTS. 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 (%). FORT COLLINS HOUSING AUTHORITY VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-125 DD=111 -200=41 TH-2 19/12 11/12 18/12 7/12 14/12 WC=8.7 DD=123 SW=1.0 WC=2.5 -200=20 WC=8.7 DD=123 SW=1.0 WC=2.5 -200=20 TH-3 14/12 14/12 10/12 4/12 WC=12.9 DD=118 SW=-0.1 WC=9.9 DD=118 SW=-0.1 WC=12.9 DD=118 SW=-0.1 WC=9.9 DD=118 SW=-0.1 TH-4 5/12 14/12 9/12 9/12 5/12 WC=4.0 DD=99 SW=-3.0 WC=7.9 DD=122 SW=0.1 WC=6.0 DD=112 SW=-0.3 WC=11.2 DD=107 SW=-0.1 WC=4.0 DD=99 SW=-3.0 WC=7.9 DD=122 SW=0.1 WC=6.0 DD=112 SW=-0.3 WC=11.2 DD=107 SW=-0.1 TH-5 14/12 18/12 12/12 9/12 9/12 WC=11.5 DD=123 SW=0.5 SS=0.010 WC=8.4 DD=126 SW=0.3 WC=11.5 DD=123 SW=0.5 SS=0.010 WC=8.4 DD=126 SW=0.3 TH-6 DEPTH - FEET DEPTH - FEET Summary Logs of Exploratory Borings FORT COLLINS HOUSING AUTHORITY FIGURE 2 VILLAGE AT HORSETOOTH CTL | T PROJECT NO. FC07464-125