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HomeMy WebLinkAboutSTREETS PARK - BASIC DEVELOPMENT REVIEW - BDR180010 - 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 STREETS FACILITY PARK SW VINE DRIVE AND LEMAY AVENUE FORT COLLINS, COLORADO ARCHITECTURE WEST, LLC 160 Palmer Drive Fort Collins, Colorado 80525 Attention: Stephen Steinbicker Project No. FC08050-125 September 29, 2017 ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE CONDITIONS 2 PROPOSED CONSTRUCTION 2 INVESTIGATION 3 SUBSURFACE CONDITIONS 3 Groundwater 4 GEOLOGIC HAZARDS 4 Expansive Soils 4 Seismicity 4 SITE DEVELOPMENT 5 Fill Placement 5 Excavations 6 FOUNDATIONS 6 Footings 7 BELOW GRADE AREAS 8 FLOOR SYSTEMS 8 WATER-SOLUBLE SULFATES 10 SURFACE DRAINAGE 10 CONSTRUCTION OBSERVATIONS 11 GEOTECHNICAL RISK 11 LIMITATIONS 11 FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS FIGURE 2 – SUMMARY LOGS OF EXPLORATORY BORINGS APPENDIX A – RESULTS OF LABORATORY TESTING APPENDIX B – SAMPLE SITE GRADING SPECIFICATIONS ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 1 SCOPE This report presents the results of our Geotechnical Investigation for the proposed park 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-17-0142) dated April 10, 2017. The report was prepared from data developed during field exploration, la- boratory testing, engineering analysis and experience with similar conditions. The report includes a description of subsurface conditions found in our explora- tory borings and discussions of site development as influenced by geotechnical considerations. Our opinions and recommendations regarding design criteria and construction details for site development, foundations, floor systems, slabs- on-grade, and drainage are provided. The report was prepared for the exclusive use of Architecture West, LLC in design and construction of the proposed im- provements. If the proposed construction differs from descriptions herein, we should be requested to review our recommendations. Our conclusions are sum- marized in the following paragraphs. SUMMARY OF CONCLUSIONS 1. Soils encountered in our borings consisted of 3 to 4 feet of sandy clay over sand and gravel. Claystone bedrock was encountered at 18½ feet to the maximum depths explored. 2. Groundwater was measured at a depth of 7 feet in one boring dur- ing drilling. When measured several days later, groundwater was encountered at depths of 10½ to 11½ feet in both borings. Existing groundwater levels are not expected to significantly affect site de- velopment. We recommend a minimum 3-foot separation between foundation elements and groundwater. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 2 3. The presence of expansive soils and bedrock, and possibly collaps- ing 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 low. We believe the recommendations presented in this report will help to control risk of damage; they will not elimi- nate that risk. Slabs-on-grade and, in some instances, foundations may be damaged. 4. Footing foundations placed on natural, undisturbed soil and/or properly compacted fill are recommended for the proposed con- struction. Design and construction criteria for foundations are pre- sented in the report. 5. We believe a slab-on-grade floor is 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. 6. Surface drainage should be designed, constructed and maintained to provide rapid removal of surface runoff away from the proposed structures. Conservative irrigation practices should be followed to avoid excessive wetting. SITE CONDITIONS The site is located east of the Fort Collins Streets Department Facility, at Vine Drive and Lemay Avenue in Fort Collins, Colorado (Figure 1). The site is approximately seven acres and relatively flat. At the time of our investigation, the lot contained an existing basketball court. An existing concrete drainage pan en- ters the site from the north, curving to exit the site’s western boundary. Ground cover consisted of grass and some trees. John Ames Ditch runs opposite Vine Drive. The Cache La Poudre River runs approximately ¾ mile to the southwest. PROPOSED CONSTRUCTION Proposed improvements will include a restroom and shade shelter. We understand the structures will be one-story, steel or masonry-framed structures connected by a trellis structure. No below grade construction is planned. Buried ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 3 utilities will be constructed. We anticipate site grading cuts and fills of less than 5 feet. INVESTIGATION The field investigation included drilling two exploratory borings at the loca- tions presented on Figure 1. The borings were drilled to depths of approximately 20 and 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 and bedrock. Summary logs of the borings, including results of field pene- tration resistance tests, are presented on Figure 2. Soil and bedrock samples obtained during drilling were returned to our la- boratory and visually examined by our geotechnical engineer. Laboratory testing was assigned and included moisture content, dry density, swell-consolidation, particle-size analysis, 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 labora- tory tests are presented in Appendix A and summarized in Table A-I. SUBSURFACE CONDITIONS Soils encountered in our borings consisted of 3 to 4 feet of sandy clay over sand and gravel. Claystone bedrock was encountered at 18½ feet to the maxi- mum depths explored. One sample of the clay tested indicated 1.4 percent swell. Further descriptions of the subsurface conditions are presented on our boring logs and in our laboratory test results. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 4 Groundwater Groundwater was measured at a depth of 7 feet in one boring during drill- ing. When measured several days later, groundwater was encountered at depths of 10½ to 11½ feet in both borings. Groundwater levels are expected to fluctuate seasonally. Groundwater is not expected to affect site development, but may affect utility installation. We recommend a minimum separation of 3 feet from groundwater to foundations and floor systems. GEOLOGIC HAZARDS Our investigation addressed potential geologic hazards, including expan- sive soils and seismicity that should be considered during planning and construc- tion. None of these hazards considered will preclude proposed construction. The following sections discuss each of these geologic hazards and associated development concerns. Expansive Soils Expansive soils and bedrock are present at the site. The presence of ex- pansive 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 seis- mic risk. As in most areas of recognized low seismicity, the record of the past earthquake activity in Colorado is incomplete. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 5 According to the 2015 International Building Code and the subsurface con- ditions 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 de- bris or deleterious organic materials are removed. If import material is used, it should be tested and approved as acceptable fill by CTL|Thompson. In general, import fill should meet or exceed the engineering qualities of the onsite soils. Ar- eas to receive fill should be scarified, moisture-conditioned and compacted to at least 95 percent of standard Proctor maximum dry density (ASTM D698, AASHTO T99). Sand soils used as fill should be moistened to within 2 percent of optimum moisture content. Clay soils should be moistened between optimum and 3 percent above optimum moisture content. The fill should be moisture-con- ditioned, placed in thin, loose lifts (8 inches or less) and compacted as described above. We should observe placement and compaction of fill during construction. Fill placement and compaction should not be conducted when the fill material is frozen. 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. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 6 Water and sewer lines are often constructed beneath areas where im- provements are planned. Compaction of trench backfill can have a significant ef- fect on the life and serviceability overlying structures. We recommend trench backfill be moisture conditioned and compacted as described 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 in- vestigation and OSHA standards, we believe the clay soils classify as Type B soils and the sand and gravel as Type C soils. Type B soils require a maximum slope inclination of 1:1 (horizontal:vertical) in dry conditions. Type C soils require a maximum slope inclination of 1.5:1 in dry conditions. Excavation slopes speci- fied by OSHA are dependent upon types of soil and groundwater conditions en- countered. 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 low-swelling clay and non-expansive granular soils are present at the anticipated foundation levels. Footing foundations are recommended for the proposed construction. Design criteria for footing founda- tions developed from analysis of field and laboratory data and our experience are presented below. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 7 Footings 1. Footings should be constructed on undisturbed natural soils or properly compacted fill (see the Fill Placement section of this re- port). All existing, 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 excava- tion, it should be removed and replaced with compacted fill. 2. Footings should be designed for a net allowable soil pressure of 1,500 psf. The soil pressure can be increased 33 percent for tran- sient loads such as wind or seismic loads. We recommend a mini- mum 3-foot separation between foundation elements and ground- water. 3. Footings should have a minimum width of at least 18 inches. Foun- dations 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. 4. The soils beneath footing pads can be assigned an ultimate coeffi- cient of friction of 0.4 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. Deflec- tion of grade beams is necessary to mobilize passive earth pres- sure; we recommend a factor of safety of 2 for this condition. Back- fill 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 reinforcement sufficient to simply span 10 feet. The reinforcement should be designed by a structural engineer. 7. We should observe completed footing excavations to confirm whether the subsurface conditions are similar to those found in our borings. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 8 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 below grade 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. It is impossible to construct slab-on-grade floors with no risk of movement. We believe movements will be less than 1 inch at this site. Slabs may be subject to heavy point loads. The structural engineer should design floor slab reinforce- ment. For design of slabs-on-grade, we recommend a modulus of subgrade re- action of 50 pci for on-site soils. 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 2015 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 recom- mended) is more beneficial below concrete slab-on-grade floors ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 9 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 mini- mized 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 flexi- ble 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 iso- lated from the slabs and constructed with flexible couplings. Where water and gas lines are connected to furnaces or heaters, the lines should be constructed with sufficient flexibility to allow for move- ment. 6. HVAC equipment supported on the slab should be provided with a collapsible connection between the furnace and the ductwork, with allowance for at least 2 inches of vertical movement. 7. The American Concrete Institute (ACI) recommends frequent con- trol joints be provided in slabs to reduce problems associated with shrinkage cracking and curling. To reduce curling, the concrete mix should have a high aggregate content and a low slump. If desired, a shrinkage compensating admixture could be added to the con- crete to reduce the risk of shrinkage cracking. We can perform a mix design or assist the design team in selecting a pre-existing mix. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 10 WATER-SOLUBLE SULFATES Concrete that comes into contact with soils can be subject to sulfate at- tack. We measured water-soluble sulfate concentration in one sample from this site. The measured concentration of water-soluble sulfates was 0.05 percent. Sulfate concentrations less than 0.1 percent indicate Class 0 exposure to sulfate attack for concrete that comes into contact with the subsoils, according to the American Concrete Institute (ACI). For this level of sulfate concentration, ACI in- dicates there are no special requirements for sulfate resistance. Superficial damage may occur to the exposed surfaces of highly permea- ble 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. 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. We recommend a minimum slope of 5 percent in the first ten feet out- side 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 con- nected to solid pipe discharge systems. We do not recommend directing roof drains under buildings. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 11 CONSTRUCTION OBSERVATIONS We recommend that CTL | Thompson, Inc. provide construction observa- tion services to allow us the opportunity to verify whether soil conditions are con- sistent with those found during this investigation. Other observations are recom- mended to review general conformance with design plans. If others perform these observations, they must accept responsibility to judge whether the recom- mendations in this report remain appropriate. GEOTECHNICAL RISK The concept of risk is an important aspect with any geotechnical evalua- tion primarily because the methods used to develop geotechnical recommenda- tions do not comprise an exact science. We never have complete knowledge of subsurface conditions. Our analysis must be tempered with engineering judg- ment and experience. Therefore, the recommendations presented in any ge- otechnical 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 recom- mendations in this report are followed during construction. Owners must assume responsibility for maintaining the structures and use appropriate practices regard- ing drainage and landscaping. Improvements performed by owners after con- struction, such as construction of additions, retaining walls, landscaping and ex- terior flatwork, should be completed in accordance with recommendations in this report. LIMITATIONS This report has been prepared for the exclusive use of Architecture West, LLC for the purpose of providing geotechnical design and construction criteria for the proposed project. The information, conclusions, and recommendations pre- sented herein are based upon consideration of many factors including, but not 55 60 65 70 75 80 85 90 95 100 55 60 65 70 75 80 85 90 95 100 6/12 WC=12.2 DD=112 SW=1.4 SS=0.050 WC=5.5 -200=12 TH-1 El. 99.0 16/12 34/12 WC=9.6 -200=18 TH-2 El. 98.0 CLAY, SANDY, MOIST, MEDIUM STIFF, BROWN, DARK BROWN (CL) LEGEND: THE BORINGS WERE DRILLED ON SEPTEMBER 5, 2017, USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. BULK SAMPLE FROM AUGER CUTTINGS. WATER LEVEL MEASURED AT TIME OF DRILLING. WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING. 1. DRIVE SAMPLE. THE SYMBOL 6/12 INDICATES 6 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. Borings Summary Logs of Exploratory ELEVATION - FEET ELEVATION - FEET NOTES: FIGURE 2 CLAYSTONE, SANDY, MOIST TO WET, OLIVE, BROWN, RUST SAND AND GRAVEL WITH COBBLES, CLAYEY, MOIST TO WET, BROWN (SC, GC) APPENDIX A RESULTS OF LABORATORY TESTING Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 112 PCF From TH - 1 AT 2 FEET MOISTURE CONTENT= 12.2 % ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTL | T PROJECT NO. FC08050-125 APPLIED PRESSURE - KSF COMPRESSION % EXPANSION Swell Consolidation Test Results FIGURE A-1 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING 0.1 1.0 10 100 Sample of GRAVEL, SANDY, CLAYEY (GC) GRAVEL 53 % SAND 35 % From TH - 1 AT 14 FEET SILT & CLAY 12 % LIQUID LIMIT % PLASTICITY INDEX % Sample of SAND, GRAVELLY, CLAYEY (SC) GRAVEL 36 % SAND 46 % From TH - 2 AT 9 FEET SILT & CLAY 18 % LIQUID LIMIT % PLASTICITY INDEX % ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTL | T PROJECT NO. FC08050-125 FIGURE A-2 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. PASSING WATER- MOISTURE DRY APPLIED NO. 200 SOLUBLE DEPTH CONTENT DENSITY SWELL* PRESSURE SIEVE SULFATES BORING (FEET) (%) (PCF) (%) (PSF) (%) (%) DESCRIPTION TH-1 2 12.2 112 1.4 200 0.05 CLAY, SANDY (CL) TH-1 14 5.5 12 GRAVEL, SANDY, CLAYEY (GC) TH-2 9 9.6 18 SAND, GRAVELLY, CLAYEY (SC) SWELL TEST RESULTS* TABLE A-I SUMMARY OF LABORATORY TESTING Page 1 of 1 * NEGATIVE VALUE INDICATES COMPRESSION. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTL|T PROJECT NO. FC08050-125 APPENDIX B SAMPLE SITE GRADING SPECIFICATIONS ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 B-1 SAMPLE SITE GRADING SPECIFICATIONS 1. DESCRIPTION This item shall consist of the excavation, transportation, placement and compac- tion of materials from locations indicated on the plans, or staked by the Engineer, as necessary to achieve building site elevations. 2. GENERAL The Geotechnical Engineer shall be the Owner's representative. The Geotech- nical Engineer shall approve fill materials, method of placement, moisture con- tents and percent compaction, and shall give written approval of the completed fill. 3. CLEARING JOB SITE The Contractor shall remove all trees, brush and rubbish before excavation or fill placement is begun. The Contractor shall dispose of the cleared material to pro- vide the Owner with a clean, neat appearing job site. Cleared material shall not be placed in areas to receive fill or where the material will support structures of any kind. 4. SCARIFYING AREA TO BE FILLED All topsoil and vegetable matter shall be removed from the ground surface upon which fill is to be placed. The surface shall then be plowed or scarified to a depth of 8 inches until the surface is free from ruts, hummocks or other uneven fea- tures, which would prevent uniform compaction by the equipment to be used. 5. COMPACTING AREA TO BE FILLED After the foundation for the fill has been cleared and scarified, it shall be disked or bladed until it is free from large clods, brought to the proper moisture content and compacted to not less than 95 percent of maximum dry density as deter- mined in accordance with ASTM D 698 or AASHTO T 99. 6. FILL MATERIALS On-site materials classifying as CL, SC, SM, SW, SP, GP, GC and GM are ac- ceptable. Fill soils shall be free from organic matter, debris, or other deleterious substances, and shall not contain rocks or lumps having a diameter greater than three (3) inches. Fill materials shall be obtained from the existing fill and other approved sources. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 B-2 7. MOISTURE CONTENT Fill materials shall be moisture treated. Clay soils placed below the building en- velope should be moisture-treated to between optimum and 3 percent above op- timum moisture content as determined from Standard Proctor compaction tests. Clay soil placed exterior to the building should be moisture treated between opti- mum and 3 percent above optimum moisture content. Sand soils can be mois- tened to within 2 percent of optimum moisture content. Sufficient laboratory com- paction 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 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. Fill placed under foundations, ex- terior 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 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 ensure that the required dry density is obtained. ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTLT PROJECT NO. FC08050-125 B-3 9. COMPACTION OF SLOPES Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction operations shall be continued until slopes are stable, but not too dense for planting, and there is no appreciable amount of loose soil on the slopes. Compaction of slopes may be done progressively in increments of three to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent fill slopes shall not exceed 3:1 (horizontal to vertical). 10. DENSITY TESTS Field density tests shall be made by the Geotechnical Engineer at locations and depths of his choosing. Where sheepsfoot rollers are used, the soil may be dis- turbed to a depth of several inches. Density tests shall be taken in compacted material below the disturbed surface. When density tests indicate that the dry density or moisture content of any layer of fill or portion thereof is below that re- quired, the particular layer or portion shall be reworked until the required dry den- sity or moisture content has been achieved. 12. SEASONAL LIMITS No fill material shall be placed, spread or rolled while it is frozen, thawing, or dur- ing unfavorable weather conditions. When work is interrupted by heavy precipi- tation, fill operations shall not be resumed until the Geotechnical Engineer indi- cates that the moisture content and dry density of previously placed materials are as specified. 13. 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. 14. 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. 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 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 2. BORING ELEVATIONS WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM REFERENCING THE TEMPORARY BENCHMARK SHOWN ON FIGURE 1. THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT. 4. 3. WC DD SW -200 LL PI UC SS - - - - - - - - INDICATES MOISTURE CONTENT (%). INDICATES DRY DENSITY (PCF). INDICATES SWELL WHEN WETTED UNDER APPROXIMATE OVERBURDEN PRESSURE (%). INDICATES PASSING NO. 200 SIEVE (%). INDICATES LIQUID LIMIT. INDICATES PLASTICITY INDEX. INDICATES UNCONFINED COMPRESSIVE STRENGTH (psf). INDICATES SOLUBLE SULFATE CONTENT (%). ARCHITECTURE WEST, LLC STREETS FACILITY PARK CTL | T PROJECT NO. FC08050-125