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HomeMy WebLinkAboutTHE FLATS AT HANSEN FARM - PDP220004 - 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 HANSEN FARM APARTMENTS NW OF TIMBERLINE ROAD & ZEPHYR ROAD FORT COLLINS, COLORADO HANSEN MF, LLC 3665 John F. Kennedy Parkway Building 2, Suite 202 Fort Collins, Colorado 80525 Attention: Brecken Schaefer Project No. FC10225-120 March 8, 2022 Revised March 10, 2022 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE CONDITIONS 2 PROPOSED CONSTRUCTION 2 INVESTIGATION 2 SUBSURFACE CONDITIONS 3 Groundwater 3 GEOLOGIC HAZARDS 3 Expansive Soils 4 Seismicity 4 SITE DEVELOPMENT 4 Fill Placement 4 Excavations 5 FOUNDATIONS 5 Footings 6 BELOW GRADE AREAS 7 FLOOR SYSTEMS 7 Exterior Flatwork 9 OVER-EXCAVATION 9 SWIMMING POOL AND POOL FLATWORK 10 PAVEMENTS 11 Pavement Selection 12 Subgrade and Pavement Materials and Construction 12 Pavement Maintenance 13 WATER-SOLUBLE SULFATES 13 SURFACE DRAINAGE 14 CONSTRUCTION OBSERVATIONS 14 GEOTECHNICAL RISK 14 LIMITATIONS 15 FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS FIGURES 2 THROUGH 4 – 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 HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 1 SCOPE This report presents the results of our Geotechnical Investigation for the proposed apartment complex in Fort Collins, Colorado. The purpose of the investigation was to evaluate the subsurface conditions and provide foundation recommendations and geotechnical design criteria for the project. The scope was described in our Service Agreement (Proposal No. FC-21-0639) dated December 2, 2021. The report was prepared from data developed during field exploration, laboratory testing, engineering analysis, and experience with similar conditions. The report includes a description of subsurface conditions found in our exploratory 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. The report was prepared for the exclusive use of Hansen MF, LLC in design and construction of the proposed improvements. If the proposed construction differs from descriptions herein, we should be requested to review our recommendations. Our conclusions are summarized in the following paragraphs. SUMMARY OF CONCLUSIONS 1. Soils encountered in our borings generally consisted of sandy clay to the depths explored. Interlayers of silt, silty sands and/or silty clays were encountered in several of the borings at depths of 14 to 19 feet. No bedrock was encountered during this investigation. 2. Groundwater was measured at depths ranging from 16 to 20 feet in 14 of the borings during drilling. When measured several days later, groundwater was encountered at depths of 14 to 18 feet across all borings. Existing groundwater levels are not expected to significantly affect site development. 3. The presence of expansive soils constitutes a geologic hazard. There is risk that slabs-on-grade and foundations will heave or settle and be damaged. We judge the risk is moderate. We believe the recommendations presented in this report will help to control risk of damage; they will not eliminate that risk. Slabs- on-grade and, in some instances, foundations may be damaged. 4. Footing foundations designed to maintain a minimum dead load placed on properly over-excavated and re-compacted fill are recommended for the HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 2 proposed construction. Design and construction criteria for foundations are presented in the report. 5. We believe a slab-on-grade floor is appropriate for this site if constructed on 4 feet of over-excavated and properly placed fill. Some movement of slab-on- grade floors should be anticipated. We expect movements will be minor, on the order of 1-inch or less following over-excavation. If movement cannot be tolerated, structural floors should be used. 6. Surface drainage should be designed, constructed, and maintained to provide rapid removal of surface runoff away from the proposed improvements. Conservative irrigation practices should be followed to avoid excessive wetting. 7. Samples of the subgrade soils generally classified as AASHTO A-6 and A-7-6 soils. For the parking lot, we recommend 4 inches of asphaltic concrete over 6 inches of aggregate base course. Thicker sections are recommended for areas with heavier traffic. SITE CONDITIONS The site is located in Fort Collins, Colorado (Figure 1). The vacant 10½-acre tract slopes gradually north. An irrigation ditch is located the south of the site, Mail Creek Ditch is located north of the site. At the time of our investigation, overlot grading was complete and utilities had been installed. PROPOSED CONSTRUCTION We understand the proposed complex will consist of three-story wood and/or steel- framed residential structures, a clubhouse structure, pool, and associated parking and accesses. No below grade construction is planned. INVESTIGATION The field investigation included drilling 15 exploratory borings at the locations presented on Figure 1. The borings were drilled to depths of approximately 20 to 30 feet using 4-inch diameter, continuous-flight augers, and a truck-mounted drill. Drilling was observed by our field representative who logged the soils. Summary logs of the borings, including results of field penetration resistance tests, are presented on Figures 2 through 4. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 3 Soil samples obtained during drilling were returned to our laboratory and visually examined by our geotechnical engineer. Laboratory testing was assigned and included moisture content, dry density, swell-consolidation, particle-size analysis, Atterberg limits, and water-soluble sulfate tests. Swell-consolidation test samples were wetted at a confining pressure which approximated the pressure exerted by the overburden soils (overburden pressures). Results of the laboratory tests are presented in Appendix A. SUBSURFACE CONDITIONS Soils encountered in our borings consisted of sandy clay to the depths explored. No bedrock was encountered during this investigation. Samples of the clay soils tested indicated 0.1 percent compression to 4.7 percent swell. Further descriptions of the subsurface conditions are presented on our boring logs and in our laboratory test results. Groundwater Groundwater was measured at depths ranging from 16 to 20 feet in 14 borings during drilling. When measured several days later, groundwater was encountered at depths of 14 to 18 feet across all borings. Groundwater may develop when a source of water not presently contributing becomes available. Groundwater levels are expected to fluctuate seasonally and with water levels in the nearby ditches. Groundwater is not expected to affect construction at the site. We recommend a minimum separation of 3 feet from groundwater to foundations and floor systems. GEOLOGIC HAZARDS Our investigation addressed potential geologic hazards, including expansive soils, and seismicity that should be considered during planning and construction. None of these hazards considered will preclude proposed construction. The following sections discuss each of these geologic hazards and associated development concerns. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 4 Expansive Soils Expansive soils and bedrock are present at the site. The presence of expansive soils and bedrock, collectively referred to as expansive or swelling soils, constitutes a geologic hazard. There is a risk that ground heave will damage slabs-on-grade and foundations. The risks associated with swelling soils can be mitigated, but not eliminated, by careful design, construction, and maintenance procedures. We believe the recommendations in this report will help control risk of foundations and/or slab damage; they will not eliminate that risk. 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 2018 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 buildings would be expected. Wind loads, not seismic considerations, typically govern dynamic structural design for the structures planned in this area. 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. Areas 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-conditioned, placed in thin, loose lifts (8 inches or less) and compacted as described above. We should observe HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 5 placement and compaction of fill during construction. 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 specifications are presented in Appendix B. Water and sewer lines are often constructed beneath areas where improvements 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 above. Placement and compaction of backfill should be observed and tested by a representative of our firm during construction. Excavations We believe 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. Based on our investigation and OSHA standards, we believe the clay soils classify as Type A soils. Type A soils require a maximum slope inclination of ¾:1 in dry conditions. Excavation slopes specified by OSHA are dependent upon types of soil and groundwater conditions encountered. The contractor’s “competent person” should identify the soils and/or rock encountered in the excavation and refer to OSHA standards to determine appropriate 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 Our investigation indicates moderately swelling soils are present at the anticipated foundation levels. Footing foundations designed to maintain a minimum dead load are recommended for the proposed construction. We recommend over-excavation to a depth of 4 feet from existing grades. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 6 Design criteria for footing foundations developed from analysis of field and laboratory data and our experience are presented below. Footings 1. Footings should be constructed on properly over-excavated and recompacted fill (see the Fill Placement section of this report). All existing, uncontrolled fill should be removed from under footings and within one footing width around footings and replaced with properly compacted fill. Where soil is loosened during excavation, it should be removed and replaced with compacted fill. 2. Footings should be designed for a net allowable soil pressure of 3,000 psf and a minimum dead load pressure of 1,000 psf. The soil pressure can be increased 33 percent for transient loads such as wind or seismic loads. We recommend a minimum 3-foot separation between foundation elements and groundwater. 3. We anticipate footings designed using the soil pressure recommended above could experience 1-inch of movement. Differential movement of ½- inch should be considered in the design. 4. Footings should have a minimum width of at least 18 inches. Foundations for isolated columns should have minimum dimensions of 24 inches by 24 inches. Larger sizes may be required depending on loads and the structural system used. 5. The soils beneath footing pads can be assigned an ultimate coefficient of friction of 0.4 to resist lateral loads. The ability of grade beam or footing backfill to resist lateral loads can be calculated using a passive equivalent fluid pressure of 250 pcf. This assumes the backfill is densely compacted and will not be removed. Deflection of grade beams is necessary to mobilize passive earth pressure; we recommend a factor of safety of 2 for this condition. Backfill should be placed and compacted to the criteria in the Fill Placement section of this report. 6. To meet the minimum deadload criteria, a continuous void with minimum 4- inch thickness should be placed below grade beams, between pads to concentrate the load of the structures on the footing pads. 7. Exterior footings should be protected from frost action. We believe 30 inches of frost cover is appropriate for this site. 8. Foundation walls and grade beams should be well reinforced both top and bottom. We recommend reinforcement sufficient to simply span 10 feet. The reinforcement should be designed by a structural engineer. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 7 9. We should observe completed footing excavations to confirm whether the subsurface conditions are similar to those found in our borings. BELOW GRADE AREAS No below grade areas are planned for the buildings. For this condition, perimeter drains are not usually necessary. Lateral earth pressure on foundation walls can be calculated using an equivalent fluid density of 50 pcf. This value is for horizontal backfill conditions and does not include pressure due to surcharge or hydrostatic pressure. 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 proposed construction if over-excavation is performed. We estimate up to 4 inches of potential heave at existing grades prior to over-excavation. 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 following over-excavation. If movement 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 minimum 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 recommend a modulus of subgrade reaction of 150 pci for on-site soils. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 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 occurs. 2. Slabs should be placed directly on exposed soils or properly moisture conditioned, compacted fill. The 2021 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 (minimum 6-mil; 10-mil recommended) is more beneficial below concrete slab-on-grade floors where floor 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 increase 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. Considerations and recommendations for the installation of vapor retarders 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 flexible 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 isolated 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 movement. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 9 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 control 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 concrete to reduce the risk of shrinkage cracking. We can perform a mix design or assist the design team in selecting a pre-existing mix. Exterior Flatwork We recommend exterior flatwork and sidewalks be isolated from foundations to reduce the risk of transferring heave, settlement or freeze-thaw movement to the structure. One alternative would be to construct the inner edges of the flatwork on haunches or steel angles bolted to the foundation walls and detailing the connections such that movement will cause less distress to the building, rather than tying the slabs directly into the building foundation. Construction on haunches or steel angles and reinforcing the sidewalks and other exterior flatwork will reduce the potential for differential settlement and better allow them to span across wall backfill. Frequent control joints should be provided to reduce problems associated with shrinkage. Panels that are approximately square perform better than rectangular areas. OVER-EXCAVATION If you are willing to accept risk of potential movements, a slab-on-grade floor and spread footing foundations can be used if constructed on an over-excavation. The over- excavation should extend at least 4 feet below the slab and foundation subgrade and at least 2 feet beyond the perimeter of the footprint of the structure. The existing on-site soils are suitable for re-use as fill material provided debris or deleterious organic materials are removed. The fill should be placed as described in the Fill Placement section of this report. For the pool area, we recommend that over-excavation extend at least 2 feet below the flatwork surrounding the pool. Shallow pools may also benefit from over-excavation. Detailed pool plans were not available for our review at the time of this investigation. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 10 SWIMMING POOL AND POOL FLATWORK Our investigation indicates that the bottom of the swimming pool, as well as flatwork around the pool, will bear on natural sandy clays. The soils encountered in our borings exhibited low to moderate swell in the upper 5+ feet. The swelling soils pose high risk of damaging the pools and/or decks in the event they swell due to increases in moisture content. Reinforced concrete or “gunite/shot-crete” type pools tend to be brittle and may be more susceptible to cracking due to shrinkage and/or movement of the subgrade soils. Alternatives to reduce the risk of damage due to these types of movements include the use of flexible plastic or fiberglass pool structures; and/or over-excavating and replacing the native materials with non-expansive fill, or moisture conditioning and recompacting the existing materials as engineered fill to provide more uniform support as described above in OVER-EXCAVATION. Fill should be constructed according to the guidelines presented below in the Fill Placement section of this report. Pool walls should be designed for lateral earth pressures where backfill is not present to about the same extent on both sides of the wall. Many factors affect the value of the design lateral earth pressure. These factors include, but are not limited to, the type, compaction, slope and drainage of the backfill, and the rigidity of the wall against rotation and deflection. For a very rigid wall where negligible or very little deflection will occur, an "at-rest" lateral earth pressure should be used in design. This is appropriate for pool design. If on-site soils are used as backfill and the backfill is not saturated, we recommend design of pool walls at this site using an equivalent fluid density of at least 55 pounds per cubic foot (pcf). This value assumes deflection; some minor cracking of walls may occur. If very little wall deflection is desired, higher design density may be appropriate. Recent experience indicates for similar subsurface conditions, most walls designed with 50 pcf to 65 pcf equivalent fluid density have performed satisfactorily. We recommend that a gravel blanket be provided beneath the pool for drainage purposes. The gravel blanket material should consist of 3/8" to 3/4" washed or crushed rock with a maximum of 5 percent passing a #200 sieve. Drains which are to discharge downslope by means of gravity (daylighted) should either be connected to a sump pit or have a cleanout HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 11 installed to facilitate monitoring and maintenance. The discharge area should be protected from damage due to animal activity, vegetation, and traffic. The discharge area should be placed so that it does not interfere with adjacent properties. We believe the pool flatwork should be constructed as slabs-on-grade bearing on a 2- foot mat of over-excavated soil. Minor cracking of the flatwork from shrinkage is likely and will require maintenance. Cracks and joints in the flatwork should be sealed regularly. The flatwork and surrounding areas should be sloped to drain away from the pool and any adjacent structures, slabs, or pavements. PAVEMENTS The project will include a paved parking lot and access drives. The performance of pavements is dependent upon the characteristics of the subgrade soil, traffic loading and frequency, climatic conditions, drainage and pavement materials. We drilled 15 exploratory borings and conducted laboratory tests to characterize the subgrade soils, which consisted of slightly moist to moist, stiff to very stiff sandy clay with low to moderate expansion potential. The subgrade soils classified as A-6 and A-7-6 soils in accordance with AASHTO procedures. The subgrade soil will likely provide poor support for new pavement. 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. We understand there will be approximately 442 parking spaces, and traffic will primarily consist of lightly-loaded passenger vehicles. Delivery and garbage truck traffic is anticipated to be minor and possibly isolated to certain areas of the parking lot. We envision that a member of the design team that ultimately configures the parking and access drives will select the locations for which the different pavement sections will be used. Flexible hot mix asphalt (HMA) over aggregate base course (ABC) is likely planned for pavement areas. Rigid Portland cement concrete (PCC) pavement should be used for trash enclosure areas and where the pavement will be subjected to frequent turning of heavy vehicles. 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. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 12 TABLE A RECOMMENDED PAVEMENT SECTIONS Classification Hot Mix Asphalt (HMA) + Aggregate Base Course (ABC) + Moisture Treated Subgrade (MTS) Portland Cement Concrete (PCC) + Moisture Treated Subgrade (MTS) Parking Area 4" HMA + 6" ABC + 12” MTS 5" PCC + 12” MTS Access Drives / Heavy Traffic Areas 5" HMA + 6" ABC + 12” MTS 6" PCC + 12” MTS Trash Enclosures - 6" PCC + 12” MTS 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 fatigue resistant pavement. However, HMA does not perform well when subjected to point loads in areas where heavy trucks turn and maneuver at slow speeds. PCC pavement is 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. The PCC pavement for trash enclosures should extend out to areas where trash trucks park to lift and empty dumpsters. 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 subgrade. The construction materials are assumed to possess sufficient quality as reflected by the strength factors used in our design calculations. Moisture treatment criteria and additional criteria for materials and construction requirements are presented in Appendix C of this report. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 13 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 preventive 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 serviceability. To restore the pavement top original serviceability, careful backfill compaction before repaving is necessary. WATER-SOLUBLE SULFATES Concrete that comes into contact with soils can be subject to sulfate attack. We measured water-soluble sulfate concentrations in three samples from this site. Concentrations were below measurable limits (<0.01 percent) across all tests conducted. 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 Institute (ACI). For this level of sulfate concentration, ACI indicates there are no special requirements for sulfate resistance. 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 materials 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 have a total air content of 6 percent ± 1.5 percent. We advocate all foundation walls and grade beams in contact with the soil (including the inside and outside faces of garage and crawl space grade beams) be damp-proofed. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 14 SURFACE DRAINAGE Performance of foundations, flatwork and pavements are influenced by changes in subgrade moisture conditions. Carefully planned and maintained surface grading can reduce the risk of wetting of the foundation soils and pavement subgrade. We recommend a minimum slope of 5 percent in the first ten feet outside foundations in landscaped areas. 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, or roof drains should be connected to solid pipe discharge systems. We do not recommend directing roof drains under buildings. CONSTRUCTION OBSERVATIONS We recommend that CTL Thompson, Inc. provide construction observation services to allow us the opportunity to verify whether soil conditions are consistent with those found during this investigation. Other observations are recommended to review general conformance with design plans. If others perform these observations, they must accept responsibility to judge whether the recommendations in this report remain appropriate. GEOTECHNICAL RISK The concept of risk is an important aspect with any geotechnical evaluation primarily because the methods used to develop geotechnical recommendations do not comprise an exact science. We never have complete knowledge of subsurface 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. Owners must assume responsibility for maintaining the structures and use appropriate practices regarding drainage and landscaping. Improvements performed by owners after construction, such as construction of additions, retaining walls, landscaping and exterior flatwork, should be completed in accordance with recommendations in this report. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 Rev 1 15 LIMITATIONS This report has been prepared for the exclusive use of Hansen MF, LLC for the purpose of providing geotechnical design and construction criteria for the proposed project. The information, conclusions, and recommendations presented herein are based upon consideration of many factors including, but not limited to, the type of construction proposed, the geologic setting, and the subsurface conditions encountered. The conclusions and recommendations contained in the report are not valid for use by others. Standards of practice evolve in the area of geotechnical engineering. The recommendations provided are appropriate for about three years. If the proposed construction is not constructed within about three years, we should be contacted to determine if we should update this report. Fifteen borings were drilled during this investigation to obtain a reasonably accurate picture of the subsurface conditions. Variations in the subsurface conditions not indicated by our borings are possible. A representative of our firm should observe foundation excavations to confirm the exposed materials are as anticipated from our borings. We should also test compaction of fill if over-excavation is used. We believe this investigation was conducted with that level of skill and care ordinarily used by geotechnical engineers practicing under similar conditions. No warranty, express or implied, is made. If we can be of further service in discussing the contents of this report or in the analysis of the influence of subsurface conditions on design of the structures, please call. CTLTHOMPSON, INC. Taylor H. Ray, PE R.B. “Chip” Leadbetter, III, PE Geotechnical Project Engineer Senior Geotechnical Engineer Via e-mail: breckens@affinitycre.com TH-1 TH-2 TH-3 TH-5 TH-6 TH-7 TH-8 TH-9 TH-14 TH-10 TH-11 TH-13 TH-12 TH-15 TH-4 TRILBY RD. ZEPHYR RD.LEMAY AVE.TIMBERLINE RD.SITE LEGEND: INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING TH-1 HANSEN MF, LLC HANSEN FARM APARTMENTS CTL I T PROJECT NO. FC10225-120 FIGURE 1 Locations of Exploratory Borings VICINITY MAP (FORT COLLINS, COLORADO) NOT TO SCALE 150'75' APPROXIMATE SCALE: 1" = 150' 0' 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 20/12 10/12 2/12 19/12 TH-1 17/12 19/12 3/12 24/12 WC=17.8LL=46 PI=28-200=72 WC=18.7DD=110SW=0.4 WC=17.8LL=46 PI=28-200=72 WC=18.7DD=110SW=0.4 TH-2 18/12 13/12 9/12 20/12 19/12 WC=17.9DD=112SW=1.4 WC=22.1DD=105SW=0.5 WC=17.9DD=112SW=1.4 WC=22.1DD=105SW=0.5 TH-3 14/12 16/12 7/12 14/12 22/12 22/12 WC=18.0DD=105SW=1.6SS=<0.01 WC=18.0DD=105SW=1.6SS=<0.01 TH-4 24/12 11/12 5/12 20/12 24/12 12/12 WC=18.7DD=109SW=1.6 WC=19.2DD=108SW=0.3 WC=18.7DD=109SW=1.6 WC=19.2DD=108SW=0.3 TH-5 Summary Logs of Exploratory Borings FIGURE 2 DEPTH - FEETDEPTH - FEETHANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-115 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 15/12 8/12 1/12 9/12 12/12 WC=12.1DD=112SW=4.3 WC=12.1DD=112SW=4.3 TH-6 12/12 7/12 5/12 7/12 WC=18.9DD=108SW=-0.1 WC=18.9DD=108SW=-0.1 TH-7 14/12 7/12 4/12 7/12 14/12 7/12 WC=17.7DD=114SW=2.5 WC=19.8DD=106SW=0.1 WC=17.7DD=114SW=2.5 WC=19.8DD=106SW=0.1 TH-8 23/12 12/12 8/12 18/12 12/12 WC=12.0DD=121SW=4.0SS=<0.01 WC=12.0DD=121SW=4.0SS=<0.01 TH-9 15/12 12/12 12/12 17/12 WC=11.8DD=121SW=4.7 WC=11.8DD=121SW=4.7 TH-10 Summary Logs of Exploratory Borings FIGURE 3 DEPTH - FEETDEPTH - FEETHANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-115 0 5 10 15 20 25 30 35 40 0 5 10 15 20 25 30 35 40 21/12 9/12 3/12 4/12 12/12 9/12 WC=11.4DD=120SW=4.7SS=<0.01 WC=11.4DD=120SW=4.7SS=<0.01 TH-11 16/12 10/12 3/12 14/12 WC=14.0LL=39 PI=19-200=73 WC=14.0LL=39 PI=19-200=73 TH-12 17/12 11/12 7/12 7/12 13/12 WC=11.2DD=116SW=3.3 WC=11.2DD=116SW=3.3 TH-13 9/12 8/12 2/12 33/12 WC=20.0DD=105SW=0.4 WC=20.0DD=105SW=0.4 TH-14 33/12 14/12 9/12 24/12 WC=15.7DD=114SW=1.7 WC=15.7DD=114SW=1.7 TH-15 DEPTH - FEETDRIVE SAMPLE. THE SYMBOL 21/12 INDICATES 21 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. CLAY, SANDY WITH OCCASIONAL SILT, SANDY AND/OR CLAYEY INTERLAYERS, SLIGHTLY MOIST TO WET, VERY SOFT TO VERY STIFF, BROWN (CL, ML) 1. NOTES: THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. 3. LEGEND:DEPTH - FEETWATER LEVEL MEASURED AT TIME OF DRILLING. Summary Logs of Exploratory Borings THE BORINGS WERE DRILLED ON FEBRUARY 4 AND 7, 2022 USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. FIGURE 4 WC DD SW -200 LL PI UC SS - - - - - - - - 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 (%). 2. HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-115 APPENDIX A RESULTS OF LABORATORY TESTING Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=112 PCF From TH - 1 AT 4 FEET MOISTURE CONTENT=18.5 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=110 PCF From TH - 2 AT 9 FEET MOISTURE CONTENT=18.7 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-1COMPRESSION % 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=112 PCF From TH - 3 AT 4 FEET MOISTURE CONTENT=17.9 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=105 PCF From TH - 3 AT 9 FEET MOISTURE CONTENT=22.1 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-2COMPRESSION % 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=105 PCF From TH - 4 AT 2 FEET MOISTURE CONTENT=18.0 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=109 PCF From TH - 5 AT 2 FEET MOISTURE CONTENT=18.7 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-3COMPRESSION % 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=108 PCF From TH - 5 AT 9 FEET MOISTURE CONTENT=19.2 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell 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) DRY UNIT WEIGHT=112 PCF From TH - 6 AT 4 FEET MOISTURE CONTENT=12.1 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-5 -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) DRY UNIT WEIGHT=108 PCF From TH - 7 AT 9 FEET MOISTURE CONTENT=18.9 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=114 PCF From TH - 8 AT 2 FEET MOISTURE CONTENT=17.7 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-6COMPRESSION % EXPANSION-4 -3 -2 -1 0 1 2 3 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE 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=106 PCF From TH - 8 AT 9 FEET MOISTURE CONTENT=19.8 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-7 -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) DRY UNIT WEIGHT=121 PCF From TH - 9 AT 4 FEET MOISTURE CONTENT=12.0 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-8 -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) DRY UNIT WEIGHT=121 PCF From TH - 10 AT 4 FEET MOISTURE CONTENT=11.8 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-9 -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) DRY UNIT WEIGHT=120 PCF From TH - 11 AT 2 FEET MOISTURE CONTENT=11.4 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-10 -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) DRY UNIT WEIGHT=116 PCF From TH - 13 AT 4 FEET MOISTURE CONTENT=11.2 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation Test Results FIGURE A-11 -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) DRY UNIT WEIGHT=105 PCF From TH - 14 AT 4 FEET MOISTURE CONTENT=20.0 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=114 PCF From TH - 15 AT 4 FEET MOISTURE CONTENT=15.7 % HANSEN MF, LLC HANSEN FARM APARTMENTS CTL | T PROJECT NO. FC10225-120 APPLIED PRESSURE -KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE A-12COMPRESSION % 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 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 18.5 112 1.3 500 CLAY, SANDY (CL) TH-2 2 17.8 46 28 72 CLAY, SANDY (CL) TH-2 9 18.7 110 0.4 1,100 CLAY, SANDY (CL) TH-3 4 17.9 112 1.4 500 CLAY, SANDY (CL) TH-3 9 22.1 105 0.5 1,100 CLAY, SANDY (CL) TH-4 2 18.0 105 1.6 150 <0.01 CLAY, SANDY (CL) TH-5 2 18.7 109 1.6 150 CLAY, SANDY (CL) TH-5 9 19.2 108 0.3 1,100 CLAY, SANDY (CL) TH-6 4 12.1 112 4.3 500 CLAY, SANDY (CL) TH-7 9 18.9 108 -0.1 1,100 CLAY, SANDY (CL) TH-8 2 17.7 114 2.5 150 CLAY, SANDY (CL) TH-8 9 19.8 106 0.1 1,100 CLAY, SANDY (CL) TH-9 4 12.0 121 4.0 500 <0.01 CLAY, SANDY (CL) TH-10 4 11.8 121 4.7 500 CLAY, SANDY (CL) TH-11 2 11.4 120 4.7 150 <0.01 CLAY, SANDY (CL) TH-12 2 14.0 39 19 73 CLAY, SANDY (CL) TH-13 4 11.2 116 3.3 500 CLAY, SANDY (CL) TH-14 4 20.0 105 0.4 500 CLAY, SANDY (CL) TH-15 4 15.7 114 1.7 500 CLAY, SANDY (CL) SWELL TEST RESULTS* TABLE A-I SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS Page 1 of 1 * NEGATIVE VALUE INDICATES COMPRESSION. HANSEN MF, LLC HANSEN FARM APARTMENTS CTL|T PROJECT NO. FC10225-120 APPENDIX B SAMPLE SITE GRADING SPECIFICATIONS HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 B-1 SAMPLE SITE GRADING SPECIFICATIONS 1. DESCRIPTION This item shall consist of the excavation, transportation, placement and compaction 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 Geotechnical Engineer shall approve fill materials, method of placement, moisture contents 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 provide 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 features, 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 determined 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 acceptable. 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. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 B-2 7. MOISTURE CONTENT Fill materials shall be moisture treated. Clay soils placed below the building envelope should be moisture-treated to between optimum and 3 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 various 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 Contractor 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 embankment 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 compacted lift thickness does not exceed 6 inches. Fill placed under foundations, exterior flatwork and pavements should be compacted to a minimum of 95 percent of maximum standard Proctor dry density (ASTM D698). Compaction, as specified above, shall be obtained by the use of sheepsfoot rollers, 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 ensure that the required dry density is obtained. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 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 disturbed 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 required, the particular layer or portion shall be reworked until the required dry density or moisture content has been achieved. 11. SEASONAL LIMITS No fill material shall be placed, spread or rolled while it is frozen, thawing, or during unfavorable weather conditions. When work is interrupted by heavy precipitation, fill operations shall not be resumed until the Geotechnical Engineer indicates that the moisture content and dry density of previously placed materials are as specified. 12. 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 advance of any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 13. REPORTING OF FIELD DENSITY TESTS Density tests performed by the Geotechnical Engineer, as specified under "Density Tests" above, shall be submitted progressively to the Owner. Dry density, moisture content and percent compaction shall be reported for each test taken. APPENDIX C PAVEMENT CONSTRUCTION RECOMMENDATIONS HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 C-1 SUBGRADE PREPARATION Moisture Treated Subgrade (MTS) 1. The subgrade should be stripped of organic matter, scarified, moisture treated and compacted to the specifications stated below in Item 2. The compacted subgrade should extend at least 3 feet beyond 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 percent 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 recompacted to the requirements for the density and moisture. As an alternative, 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. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 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 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 commence 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 modified asphalt cement, or make use of up to 20 percent reclaimed asphalt pavement (RAP). A job mix design is recommended and periodic 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 percent of the aggregate retained on the No. 4 sieve with two mechanically fractured faces. 3. Gradations that approach the maximum density line (within 5 percent between the No. 4 and 50 sieves) should be avoided. A gradation with a nominal maximum size of 1 or 2 inches developed on the fine side of the maximum density line should be used. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 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 percent and 80 percent of voids filled. 5. Asphalt cement should meet the requirements of the Superpave Performance Graded (PG) Binders. The minimum performing asphalt 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 passing 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 surfaces that are free of water, snow and ice. Paving should only be performed when both air and surface temperatures equal, or exceed, the temperatures specified in Table 401-3 of the 2006 Colorado Department of Transportation Standard Specifications for Road and Bridge Construction. 8. HMA should not be placed at a temperature lower than 245oF for mixes containing PG 64-22 asphalt, and 290oF for mixes containing polymer-modified asphalt. The breakdown compaction should be completed before the HMA temperature drops 20oF. 9. Wearing surface course shall be Grading S or SX for residential roadway classifications and Grading S for collector, arterial, industrial, 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 Maximum Theoretical Density. The surface shall be sealed with a finish roller prior to the mix cooling to 185oF. 13. Placement and compaction of HMA should be observed and tested by a representative of our firm. Placement should not commence HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 C-4 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- rolling 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 projects. 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 specifications. 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. Atomizing 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 protect the pavement against moisture loss, rapid temperature change, freezing, and mechanical injury. 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. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 C-5 10. All joints should be properly sealed using a rod back-up and approved 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 commence until the subgrade is properly prepared and tested. APPENDIX D PAVEMENT MAINTENANCE PROGRAM HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 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 preventive maintenance treatments. c. Crack sealing should be performed annually as new cracks appear. 2. 3 to 5 Year Preventive Maintenance a. The owner should budget for a preventive treatment at approximate 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. HANSEN MF, LLC HANSEN FARM APARTMENTS CTLT PROJECT NO. FC10225-120 D-2 MAINTENANCE RECOMMENDATIONS FOR RIGID PAVEMENTS High traffic volumes create pavement rutting and smooth polished surfaces. 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 preventive maintenance. c. Crack sealing should be performed annually as new cracks appear. 2. 4 to 8 Year Preventive Maintenance a. The owner should budget for a preventive treatment at approximate 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 damage, and material failure. b. Asphalt concrete overlays may be required at 15 to 20 year intervals to improve the structural capacity of the pavement.