GEOTECHNICAL INVESTIGATION PROPOSED STORAGE BUILDING AND FUELING FACILTIY WARD ALTERNATIVE ENERGY 614 EAST VINE FORT COLLINS, COLORADO

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1 GEOTECHNICAL INVESTIGATION PROPOSED STORAGE BUILDING AND FUELING FACILTIY 614 EAST VINE FORT COLLINS, COLORADO 3436 New Castle Drive Loveland, Colorado Attention: Corey Stinar Project No. FC December 17, North Link Lane Fort Collins, Colorado Telephone: Fax:

2 TABLE OF CONTENTS SCOPE 1 SUMMARY OF CONCLUSIONS 1 SITE CONDITIONS AND PROPOSED CONSTRUCTION 2 INVESTIGATION 2 SUBSURFACE CONDITIONS 3 Existing Fill 3 SEISMICITY 4 SITE DEVELOPMENT 4 Fill Placement 4 Excavations 5 FOUNDATIONS 6 Spread Footings 6 BELOW GRADE AREAS 7 FLOOR SYSTEMS 7 WATER-SOLUBLE SULFATES 10 SURFACE DRAINAGE 10 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

3 SCOPE This report presents the results of our Geotechnical Investigation for the proposed storage building and fueling facility 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 , dated August 27, 2015). 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, slabson-grade and drainage are provided. If the proposed construction changes, 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 consisted of 6 to 10 feet of sandy clay over sand, gravel and cobbles underlain by claystone bedrock. Groundwater was measured at depths of about 6 to 8 ½ feet. Existing groundwater levels are not expected to significantly affect the proposed construction. 2. Existing fill was encountered in all five borings at depths of 2 to 5 feet. Existing fill should not support foundations or floor slabs. We recommend removal and recompaction of the existing fill beneath the building. 3. We believe the proposed structures can be constructed on spread footing foundations placed on properly compacted fill. Foundation design and construction recommendations are presented in this report. 1

4 4. We believe a slab-on-grade floor is appropriate for this site. Some movement of slab-on-grade floors should be anticipated. We expect movements will be minor, on the order of 1 inch or less. If movement cannot be tolerated, structural floors should be considered. SITE CONDITIONS AND PROPOSED CONSTRUCTION The site is located north of East Vine Drive and west of Redwood Street in Fort Collins, Colorado (Figure 1). TH-4 and TH-5 were located in a paved area between two existing buildings on the west side of the property. TH-1 through TH-3 were located on the northwest side of the gravel covered parking area on the north side of the property. The proposed construction area is relatively flat. We understand the proposed buildings will be one-story, wood and/or steelframed structures. No below grade construction is planned. INVESTIGATION Subsurface conditions were investigated by drilling five borings to depths of approximately 20 to 30 feet. The approximate locations of the borings are shown on Figure 1. Our field representative observed drilling, logged the soils and bedrock found in the borings and obtained samples. Sampling was performed by driving a 2.5-inch O.D. modified California sampler with blows of a 140-pound hammer falling 30 inches and by driving a 2.0-inch O.D. split spoon sampler. These methods are standard penetration tests, and are typical for local practice. Groundwater measurements were taken during drilling and one, or more, days after drilling. Summary logs of the borings, including results of field penetration resistance tests, are presented on Figure 2. Samples obtained during drilling were returned to our laboratory and visually examined by the geotechnical engineer for this project. Laboratory analyses 2

5 included moisture content, dry density, swell-consolidation and water-soluble sulfate tests. Results of laboratory tests are presented in Appendix A and summarized in Table A-I. SUBSURFACE CONDITIONS Soils encountered in our borings consisted of 6 to 10 feet of sandy clay over sand, gravel and cobbles underlain by claystone bedrock to the depths explored. Samples of the sandy clay exhibited compression of 0.1 and 0.2 percent and expansion of 0.7 and 0.9 percent when wetted under approximate overburden pressures. The sand and gravel soils encountered in our borings classified as medium dense to dense with fines contents (percent passing No. 200 sieve) ranging from 6 to 23 percent. Atterberg limits testing of the claystone bedrock indicated moderate plasticity and fines content was determined to be 75 percent. Groundwater was measured at depths of about 6 to 8 ½ feet. Existing groundwater levels are not expected to significantly affect the proposed construction. Groundwater is expected to fluctuate seasonally. Further description of the subsurface conditions is presented on our boring logs (Figure 2) and in our laboratory testing (Appendix A). Existing Fill Up to about 5 feet of sandy clay fill was encountered in all five of the test holes. The existing fill may be deeper in some areas. Compaction records for the existing fill were not available for our review. The fill material is considered unsuitable for structural support unless documentation can be provided that indicates otherwise. We recommend removal of the fill. The existing fill can be used as new fill provided debris and vegetation are substantially removed. 3

6 SEISMICITY This area, like most of central Colorado, is subject to a low degree of seismic risk. As in most areas of recognized low seismicity, the record of the past earthquake activity in Colorado is incomplete. According to the 2012 International Building Code and the subsurface conditions encountered in our borings, this site probably classifies as a Site Class D. Only minor damage to relatively new, properly designed and built buildings would be expected. Wind loads, not seismic considerations, typically govern dynamic structural design 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). Fill placed on the upper sandy clay may be difficult to compact and may require a layer of granular material be crowded into soft soils and stabilized prior to fill placement. 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 placement and compaction of fill during construction. Fill placement and compaction should not be conducted when the fill material is frozen. 4

7 Existing fill was encountered in all five borings to depths of up to 5 feet. Deeper fill areas may be encountered during site development. The fill is of unknown origin and age. The fill presents a risk of settlement or heave to improvements constructed on the fill. We recommend the fill be removed and recompacted in the building area. The fill removal area should extend beyond the building footprint at least one footing width. If the excavations to remove existing fill are deeper than about 10 feet in the planned building area, additional measures should be considered to reduce the potential settlement of backfill. We should be advised if any of the excavations are deeper than 10 feet below the proposed floor. The excavation can be filled with on-site soils, moisture-conditioned and compacted as described above. This procedure should remove the existing fill and provide more uniform support for improvements. 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 in the Fill Placement section of this report. Placement and compaction of fill and backfill should be observed and tested by a representative of our firm during construction. Excavations The materials found in our borings can be excavated using conventional heavy-duty excavation equipment. However, some of the soils are soft and will 5

8 be displaced if wheeled equipment is used in the excavations. We recommend wheeled traffic not be allowed in the excavations. Excavations should be sloped or shored to meet local, State and Federal safety regulations. Excavation slopes specified by OSHA are dependent upon types of soil and groundwater conditions 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 sandy clay and sand, gravel and cobbled soils are present at the anticipated foundation levels. Spread footing foundations are considered appropriate for the conditions encountered. Design criteria for spread footing foundations developed from analysis of field and laboratory data and our experience are presented below. Spread Footings 1. Footings should be constructed on properly compacted fill (see the Fill Placement section of this report). All existing man-placed fill should be removed from under footings and within one footing width around footings and replaced with engineered fill. Where soil is loosened during excavation, it should be removed and replaced with on-site soils compacted following the criteria in the Fill Placement section of this report. 2. Footings constructed on the natural soils and/or engineered fill can be designed for a net allowable soil pressure of 2,000 psf. The soil pressure can be increased 33 percent for transient loads such as wind or seismic loads. 6

9 3. Footings should have a minimum width of at least 16 inches. Foundations for isolated columns should have minimum dimensions of 18 inches by 18 inches. Larger sizes may be required depending on loads and the structural system used. 4. The soils beneath footing pads can be assigned an ultimate coefficient of friction of 0.45 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 300 pcf. This assumes the backfill is densely compacted and will not be removed. Backfill should be placed and compacted to the criteria in the Fill Placement section of this report. 5. Exterior footings should be protected from frost action. We believe 30 inches of frost cover is appropriate for this site. 6. Foundation walls and grade beams should be well reinforced both top and bottom. We recommend the amount of steel equivalent to that required for a simply supported span of 10 feet. 7. We should observe completed footing excavations to confirm that the subsurface conditions are similar to those found in our borings. Occasional loose soils may be found in foundation excavations. If this occurs, we recommend the loose soils be treated as discussed in Item 1 above. BELOW GRADE AREAS No below grade areas are planned for the buildings. For this condition, perimeter drains are not usually necessary. We should be contacted to provide foundation drain recommendations if plans change to include basement areas. FLOOR SYSTEMS In our opinion, it is reasonable to use slab-on-grade floors for the proposed 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. The existing fill is not an acceptable subgrade for a slab-on-grade floor and should be completely removed from below the floor. 7

10 It is impossible to construct slab-on-grade floors with no risk of movement. We believe movements due to swell will be less than 1 inch at this site. If 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 4 inches. The minimum void should be constructed below beams and utilities that penetrate the floor. The floor may be cast over void form. Void form should be chosen to break down quickly after the slab is placed. We recommend against the use of wax or plastic-coated void boxes. Slabs may be subject to heavy point loads. The structural engineer should design floor slab reinforcement. For design of slabs-on-grade, we recommend a modulus of subgrade reaction of 50 pci for on-site soils. If the owner elects to use slab-on-grade construction and accepts the risk of movement and associated damage, we recommend the following precautions for slab-on-grade construction at this site. These precautions can help reduce, but not eliminate, damage or distress due to slab movement. 1. Slabs should be separated from exterior walls and interior bearing members with a slip joint that allows free vertical movement of the slabs. This can reduce cracking if some movement of the slab occurs. 2. Slabs should be placed directly on exposed soils or properly moisture conditioned, compacted fill. The 2012 International Building Code (IBC) requires a vapor retarder be placed between the base course or subgrade soils and the concrete slab-on-grade floor. The merits of installation of a vapor retarder below floor slabs depend on the sensitivity of floor coverings and building use to moisture. A 8

11 properly installed vapor retarder (10 mil minimum) 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 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. 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. 9

12 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 measured between 0.01 and 0.15 percent, with one sample having sulfate concentration between 0.1 and 0.2 percent. Watersoluble sulfate concentrations between 0.1 and 0.2 percent indicate Class 1 exposure to sulfate attack, according to the American Concrete Institute (ACI). ACI indicates adequate sulfate resistance can be achieved by using Type II cement with a water-to-cementitious material ratio of 0.50 or less. ACI also indicates concrete in Class 1 exposure environments should have a minimum compressive strength of 4000 psi. In our experience, superficial damage may occur to the exposed surfaces of highly permeable concrete, even though sulfate levels are relatively low. To control this risk and to resist freeze-thaw deterioration, the waterto-cementitious material ratio should not exceed 0.50 for concrete in contact with soils that are likely to stay moist due to surface drainage or high water tables. Concrete should be air entrained. SURFACE DRAINAGE Performance of foundations, flatwork and pavements are influenced by changes in subgrade moisture conditions. Carefully planned and maintained surface grading can reduce the risk of wetting of the foundation soils and pavement subgrade. Positive drainage should be provided away from foundations. Backfill around foundations should be moisture treated and compacted as described in Fill Placement. Roof drains should be directed away from buildings. Downspout extensions and splash blocks should be provided at discharge points. 10

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14 APPROXIMATE SCALE: 1" = 150' 150' COLLEGE AVE. / HWY 287 REDWOOD DR. LINDEN ST. CONIFER ST. SITE E. VINE DR. LEMAY AVE. VICINITY MAP FORT COLLINS, COLORADO NOT TO SCALE LEGEND: TH-1 INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING TH-1 TH-2 Proposed Storage Building TH-3 Redwood Drive TH-4 Proposed Fuel Facility CNG TH-5 Existing Buildings East Vine Drive Locations of Exploratory Borings CTL I T PROJECT NO. FC FIGURE 1

15 TH-1 TH-2 TH-3 TH-4 TH-5 LEGEND: 0 0 FILL; CLAY, SANDY, MOIST, BROWN, DARK BROWN CLAY, SANDY, MOIST, SOFT TO VERY STIFF, BROWN, DARK BROWN (CL) 5 31/12 4/12 WC=25.7 DD=98 SW=-0.1 SS= /12 WC=22.8 DD=101 SW=-0.2 SS= /12 WC=17.9 DD=110 SW=0.7 SS= /12 WC=24.6 DD=102 SW=0.9 5 SAND, GRAVEL, COBBLES, MOIST TO WET, MEDIUM DENSE TO DENSE, BROWN (SP-SC, GC) CLAYSTONE, SANDY, MOIST, GRAY (BEDROCK) 10 23/12 WC= =6 15/12 16/12 10 DRIVE SAMPLE. THE SYMBOL 31/12 INDICATES 31 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES DRIVE SAMPLE. THE SYMBOL INDICATES BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.0-INCH O.D. SAMPLER INCHES. DEPTH - FEET DEPTH - FEET BULK SAMPLE FROM AUGER CUTTINGS. WATER LEVEL MEASURED AT TIME OF DRILLING. WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING NOTES: 1. THE BORINGS WERE DRILLED ON DECEMBER 2, 2015, USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN THIS REPORT WC DD SW -200 SS INDICATES MOISTURE CONTENT (%). INDICATES DRY DENSITY (PCF). INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%). INDICATES PASSING NO. 200 SIEVE (%). INDICATES SOLUBLE SULFATE CONTENT (%) CTL T PROJECT NO. FC Summary Logs of Exploratory Borings FIGURE 2

16 APPENDIX A RESULTS OF LABORATORY TESTING

17 COMPRESSION % EXPANSION COMPRESSION % EXPANSION 3 2 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING APPLIED PRESSURE - KSF Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 98 PCF From TH - 2 AT 4 FEET MOISTURE CONTENT= 25.7 % 3 2 ADDITIONAL COMPRESSION UNDER CONSTANT PRESSURE DUE TO WETTING APPLIED PRESSURE - KSF Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 101 PCF From TH - 3 AT 4 FEET MOISTURE CONTENT= 22.8 % CTL T PROJECT NO. FC Swell Consolidation FIGURE A-1

18 COMPRESSION % EXPANSION COMPRESSION % EXPANSION 3 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING APPLIED PRESSURE - KSF Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 110 PCF From TH - 4 AT 4 FEET MOISTURE CONTENT= 17.9 % 3 2 EXPANSION UNDER CONSTANT PRESSURE DUE TO WETTING APPLIED PRESSURE - KSF Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 102 PCF From TH - 5 AT 4 FEET MOISTURE CONTENT= 24.6 % CTL T PROJECT NO. FC Swell Consolidation FIGURE A-2

19 PERCENT PASSING PERCENT RETAINED PERCENT PASSING PERCENT RETAINED HYDROMETER ANALYSIS SIEVE ANALYSIS 25 HR. 7 HR. TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS 45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. *200 *100 *50 *40 *30 *16 *10 *8 *4 3/8" 3/4" 1½" 3" 100 5" 6" 8" CLAY (PLASTIC) TO SILT (NON-PLASTIC) DIAMETER OF PARTICLE IN MILLIMETERS SANDS FINE MEDIUM COARSE Sample of GRAVEL, SANDY, CLAYEY (GC) GRAVEL 39 % SAND 38 % From TH - 1 AT 9 FEET SILT & CLAY 23 % LIQUID LIMIT % PLASTICITY INDEX % GRAVEL 76.2 FINE COARSE COBBLES HYDROMETER ANALYSIS SIEVE ANALYSIS 25 HR. 7 HR. TIME READINGS U.S. STANDARD SERIES CLEAR SQUARE OPENINGS 45 MIN. 15 MIN. 60 MIN. 19 MIN. 4 MIN. 1 MIN. *200 *100 *50 *40 *30 *16 *10 *8 *4 3/8" 3/4" 1½" 3" " 6" 8" DIAMETER OF PARTICLE IN MILLIMETERS CLAY (PLASTIC) TO SILT (NON-PLASTIC) SANDS FINE MEDIUM COARSE GRAVEL FINE COARSE COBBLES Sample of SAND, GRAVELLY, CLAYEY (SP-SC) GRAVEL 44 % SAND 50 % From TH - 3 AT 9 FEET SILT & CLAY 6 % LIQUID LIMIT % PLASTICITY INDEX % CTL T PROJECT NO. FC Gradation Test Results FIGURE A-3

20 TABLE A-I SUMMARY OF LABORATORY TESTING ATTERBERG LIMITS SWELL TEST RESULTS* 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 GRAVEL, SANDY, CLAYEY (GC) TH CLAY, SANDY (CL) TH CLAY, SANDY (CL) TH SAND, GRAVELLY, CLAYEY (SP-SC) TH CLAYSTONE TH CLAY, SANDY (CL) TH CLAY, SANDY (CL) * NEGATIVE VALUE INDICATES COMPRESSION. CTL T PROJECT NO. FC Page 1 of 1

21 APPENDIX B SAMPLE SITE GRADING SPECIFICATIONS

22 1. DESCRIPTION SAMPLE SITE GRADING SPECIFICATIONS 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 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. B-1

23 7. MOISTURE CONTENT Fill materials shall be moisture treated. Clay soils placed below the building envelope should be moisture-treated to between 1 and 4 percent above optimum moisture content as determined from Standard Proctor compaction tests. Clay soil placed exterior to the building should be moisture treated between optimum and 3 percent above optimum moisture content. Sand soils can be moistened to within 2 percent of optimum moisture content. Sufficient laboratory compaction tests shall be performed to determine the optimum moisture content for the 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. 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 insure that the required dry density is obtained. B-2

24 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. COMPLETED PRELIMINARY GRADES All areas, both cut and fill, shall be finished to a level surface and shall meet the following limits of construction: A. Overlot cut or fill areas shall be within plus or minus 2/10 of one foot. B. Street grading shall be within plus or minus 1/10 of one foot. The civil engineer, or duly authorized representative, shall check all cut and fill areas to observe that the work is in accordance with the above limits. 12. SUPERVISION AND CONSTRUCTION STAKING Observation by the Geotechnical Engineer shall be continuous during the placement of fill and compaction operations so that he can declare that the fill was placed in general conformance with specifications. All site visits necessary to test the placement of fill and observe compaction operations will be at the expense of the Owner. All construction staking will be provided by the Civil Engineer or his duly authorized representative. Initial and final grading staking shall be at the expense of the owner. The replacement of grade stakes through construction shall be at the expense of the contractor. B-3

25 13. 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. 14. NOTICE REGARDING START OF GRADING The contractor shall submit notification to the Geotechnical Engineer and Owner advising them of the start of grading operations at least three (3) days in advance of the starting date. Notification shall also be submitted at least 3 days in advance of any resumption dates when grading operations have been stopped for any reason other than adverse weather conditions. 15. REPORTING OF FIELD DENSITY TESTS Density tests performed by the Geotechnical Engineer, as specified under "Density Tests" above, shall be submitted progressively to the Owner. Dry density, moisture content and percent compaction shall be reported for each test taken. 16. DECLARATION REGARDING COMPLETED FILL The Geotechnical Engineer shall provide a written declaration stating that the site was filled with acceptable materials, or was placed in general accordance with the specifications. B-4

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