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HomeMy WebLinkAbout611 LAPORTE AVE - CARRIAGE HOUSE - FDP230018 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT CTL|Thompson, Inc. Denver, Fort Collins, Colorado Springs, Glenwood Springs, Pueblo, Summit County – Colorado Cheyenne, Wyoming and Bozeman, Montana Proposed Carriage House 611 Laporte Avenue Fort Collins, Colorado Prepared for: Hutch Design & Build 5361 Moonlight Bay Drive Windsor, Colorado 80528 Attention: Noah Hutchison Project No. FC10560-120 October 11, 2022 GEOTECHNICAL INVESTIGATION Table of Contents HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 Scope 1 Summary Of Conclusions 1 Site Conditions and Proposed Construction 2 Investigation 2 Subsurface Conditions 2 Geologic Hazards 3 Site Development 4 Fill Placement 4 Excavations 4 Foundations 5 Footings 5 Below Grade Areas 6 Floor Systems 6 Exterior Flatwork 8 Subsurface Drainage 8 Construction Observations 8 Geotechnical Risk 9 Limitations 9 FIGURE 1 – LOCATION OF EXPLORATORY BORING FIGURE 2 – SUMMARY LOG OF EXPLORATORY BORING FIGURE 3 – RESULTS OF LABORATORY TESTING TABLE I – SUMMARY OF LABORATORY TESTING APPENDIX A – SAMPLE SITE GRADING SPECIFICATIONS HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 1 Scope This report presents the results of our Geotechnical Investigation for the proposed 1,000 square-foot carriage house at 611 Laporte Avenue 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-22-0338) dated August 10, 2022. 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 boring and discussions of site development as influenced by geotechnical considerations. Our opinions and recommendations regarding design criteria and construction details for site development, foundations, floor systems, slabs-on-grade, lateral earth loads, and drainage are provided. The report was prepared for the exclusive use of Hutch Design and Build 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 boring consisted sandy clay to the depth explored of 20 feet. Samples of the clay tested indicated low swelling soils are present at this site. No groundwater or bedrock was encountered during our investigation. 2. 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 low. 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. 3. Footing foundations placed on natural, undisturbed soil and/or properly compacted fill are recommended for the proposed construction. Design and construction criteria for foundations are presented in the report. 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 2 5. Surface drainage should be designed, constructed, and maintained to provide rapid removal of surface runoff away from the proposed structure. Conservative irrigation practices should be followed to avoid excessive wetting. Site Conditions and Proposed Construction The site is located 611 Laporte Avenue in Fort Collins, Colorado (Figure 1). The site is developed with an existing residence and shed. We understand a 1,000 square-foot carriage house is to be constructed in the rear of the lot. The structure will be two stories with a garage, office, and mudroom on the ground floor and a studio apartment on the second floor. Investigation The field investigation included drilling one exploratory boring at the location presented on Figure 1. The boring was drilled to a depth of approximately 20 feet using 4-inch diameter continuous-flight augers, and a truck-mounted drill. Drilling was observed by our field representative who logged the soils. A summary log of the boring, including results of field penetration resistance tests, is presented on Figure 2. 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, and swell-consolidation 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 on Figure 3 and summarized in Table I. Subsurface Conditions Soils encountered in our boring consisted sandy clay to the depth explored of 20 feet. Samples of the clay tested indicated swells of 0.2 and 0.7 percent. No groundwater or bedrock was encountered during our investigation. Groundwater may develop on or near low permeable soil layers when a source of water not presently contributing becomes available. Groundwater levels are expected to fluctuate seasonally. Further descriptions of the subsurface conditions are presented on our boring log and in our laboratory test results. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 3 Geologic Hazards Colorado is a challenging location to practice geotechnical engineering. The climate is relatively dry, and the near-surface soils are typically dry and relatively stiff. These soils and related sedimentary bedrock formations tend to react to changes in moisture conditions. Some of the soils and bedrock swell as they increase in moisture and are called expansive soils. Other soils can settle significantly upon wetting and are referred to as collapsing soils. Most of the land available for development east of the Front Range is underlain by expansive clay or claystone bedrock near the surface. The soils that exhibit collapse are more likely west of the continental divide; however, both types of soils occur all over the state. Covering the ground with houses, streets, driveways, patios, etc., coupled with lawn irrigation and changing drainage patterns, leads to an increase in subsurface moisture conditions. As a result, some soil movement is inevitable. It is critical that all recommendations in this report are followed to increase the chances that the foundations and slabs-on-grade will perform satisfactorily. After construction, homeowners must assume responsibility for maintaining the structure and use appropriate practices regarding drainage and landscaping. Expansive soils are present at this site. The presence of expansive soils, collectively referred to as expansive or swelling soils, constitutes a geologic hazard. There is risk that ground heave or settlement will damage slabs-on-grade and foundations. The risks associated with swelling and compressible 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 foundation and/or slab damage; they will not eliminate that risk. The builder and homeowners should understand that slabs-on-grade and, in some instances, foundations may be affected. Homeowner maintenance will be required to control risk. We recommend the builder provide a booklet to the homeowners that describes swelling soils and includes recommendations for care and maintenance of homes constructed on expansive soils. Colorado Geological Survey Special Publication 431 was designed to provide this information. 1“A Guide to Swelling Soils for Colorado Homebuyers and Homeowners,” Second Edition Revised and Updated by David C. Noe, Colorado Geological Survey, Department of Natural Resources, Denver, Colorado, 2007. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 4 Site Development Fill Placement The existing onsite soils are suitable for re-use as fill material provided debris or deleterious organic materials are removed. If import material is used, it should be tested and approved as acceptable fill by CTL|Thompson. In general, import fill should meet or exceed the engineering qualities of the onsite soils. 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 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 A. Excavations We believe the materials found in our boring 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 B soils. Type B soils require a maximum slope inclination of 1:1 (horizontal:vertical) 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 5 Foundations Our investigation indicates low swelling soils are present at the anticipated foundation levels. Footing foundations are recommended for the proposed construction. Design criteria for footing and drilled pier foundations developed from analysis of field and laboratory data and our experience are presented below. Footings 1. Footings should be constructed on undisturbed natural soils or properly compacted 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 1,500 psf. The soil pressure can be increased 33 percent for transient loads such as wind or seismic loads. 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 12 inches. Foundations for isolated columns should have minimum dimensions of 16 inches by 16 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. Exterior footings should be protected from frost action. We believe 30 inches of frost cover is appropriate for this site. 7. 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. 8. We should observe completed footing excavations to confirm whether the subsurface conditions are similar to those found in our boring. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 6 Below Grade Areas No below grade areas are planned for the building. 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. 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 100 pci for onsite 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 7 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 flexibilit y 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 8 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. Subsurface 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 9 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. Limitations This report has been prepared for the exclusive use of Hutch Design and Build 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. One boring was drilled during this investigation to obtain a reasonably accurate picture of the subsurface conditions. Variations in the subsurface conditions not indicated by our boring are possible. A representative of our firm should observe foundation excavations to confirm the exposed materials are as anticipated from our boring. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 10 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. Spencer Schram, PE John Byers Geotechnical Project Manager Engineering Technician TH-1 Whitcomb StreetLaporte Avenue LOOMIS AVE.LAPORTE AVE. MOUNTAIN AVE.WHITCOMB ST.SITE MAPLE ST. LEGEND: INDICATES APPROXIMATE LOCATION OF EXPLORATORY BORING INDICATES APPROXIMATE PROPERTY LINE TH-1 HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTL I T PROJECT NO. FC10560-120 Location of Exploratory Boring FIGURE 1 VICINITY MAP (FORT COLLINS, COLORADO) NOT TO SCALE 50'25' APPROXIMATE SCALE: 1" = 50' 0' 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 12/12 12/12 WC=7.9 DD=107 SW=0.7 8/12 17/12 WC=14.2 DD=119 SW=0.2 22/12 TH-1 CLAY, SLIGHTLY SANDY TO SANDY, SLIGHTLY MOIST TO MOIST, STIFF, BROWN (CL) LEGEND: DRIVE SAMPLE. THE SYMBOL 12/12 INDICATES 12 BLOWS OF A 140-POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES. Boring NOTES: THE BORING WAS DRILLED ON SEPTEMBER 8TH, 2022 USING 4-INCH DIAMETER CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG. 3. 1. 2. Exploratory Summary Log of FIGURE 2 WC DD SW -200 LL PI UC SS - - - - - - - -DEPTH - FEETDEPTH - FEETINDICATES 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 (%). HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTL | T PROJECT NO. FC10560-120 LIMITATIONS AND CONCLUSIONS IN THIS REPORT. THIS LOG SUBJECT TO THE EXPLANATIONS, THIS INVESTIGATION NO GROUNDWATER WAS ENCOUNTERED DURING 4. Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=107 PCF From TH - 1 AT 4 FEET MOISTURE CONTENT=7.9 % Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT=119 PCF From TH - 1 AT 14 FEET MOISTURE CONTENT=14.2 % HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTL | T PROJECT NO. FC10560-120 APPLIED PRESSURE - KSF APPLIED PRESSURE -KSFCOMPRESSION % EXPANSIONSwell Consolidation FIGURE 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 APPLIEDDRYMOISTURE SWELL*DEPTH PRESSUREDENSITYCONTENT BORING (FEET)(%)(PCF)(%)(PSF)DESCRIPTION CLAY, SANDY (CL)5000.71077.94TH-1 TH-1 14 14.2 119 0.2 1,800 CLAY, SANDY (CL) SWELL TEST RESULTS* TABLE I SUMMARY OF LABORATORY TESTING Page 1 of 1CTL|T PROJECT NO. FC10560-120 611 LAPORTE CARRIAGE HOUSE HUTCH DESIGN & BUILD * NEGATIVE VALUE INDICATES COMPRESSION. APPENDIX A SAMPLE SITE GRADING SPECIFICATIONS HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 A-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. 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 A-2 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. 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. HUTCH DESIGN & BUILD 611 LAPORTE CARRIAGE HOUSE CTLT PROJECT NO. FC10560-120 A-3 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.