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HomeMy WebLinkAboutTract Map 3929 Lot 158 Results of Compaction Rough Grading . . 'W. C. HOBBS, CONSULTING ENGINEER 29284 OLD WRANGLER ROAD CANYON LAKE, CALIFORNIA 92587 (909) 244-5177 Project No: 98056-2 Date: October 29, 1998 ITom and Pam Shipley !30246 Villa A1turas ITemecula, CalifOOlia 92592 Subject: Resultslof Compaction Testing Owing Rough Grading, Lot 158, Tract 3929, Monte Verde Road Temecula, California, APN .Dear Mr. and Mrs. Shipley, I'Rt ~ I..6rlSS AECEIV;:I"" OCT 3 0 1998 ENG/~l{~tJ~~~r#i~ENi Contained herein are the resu~s of compaction testing and observations made during rough grade operations for the house pad area at the subject site. The location of the tests are plotted on a portion of the grading plan and the test results are contained in the attached Appendix A. It should be noted that observation and testing for the pad and drive areas was performed on a periodic basis, and portions of the information relative to procedures used was provided by the grading contractor and by direct observation. This observation and testing was performed in accordance with generally accepted engineering practices. The conclusions and recommendations contained in this report were based on the data available and the interpretation of such data as dictated by our experience and background. Hence, our conclusions and recomm~ndations are professional opinions; therefore, no other warranty is offered or implied. Accompanying Illustrations and Appendices Test Location Map, Plate 1 ~pendix A, Summary of Field Density and Laboratory Test Results \ . . 'Mr. and Mrs. Shipley, Lot 158, Tr. 3929, Monte Verde Rd., Temecula Page: 2 Project No: 98056,2 Summary of Earthwork . General Site grading was conducted during the month of October, 1998, by Kemmis Equipment of ITemecula, California. Rough Grading !Areas to receive fill or to be processed were first stripped of vegetation that was disposed of properly on the site or otherwise removed from the site. The ground to receive fill was scarified to a depth of 12 inches, brought to near optimum moisture content and compacted to the minimum requirements prior to the placement of fill. Fill was placed in 12-inch loose lifts, brought to a uniform near optimum moisture content and compacted to a minimum of 90 percent relative compaction. This is relative to the maximum dry density as determined in accordance with ASTM test designation 0 1557-78. Grading was accomplished with the use of a 0-4 size Dozer. Water was added when necessary with the use of a water hose drawing from a meter. Compaction was achieved by repeated passes of the heavy equipment over each lift of fill. A key was excavated a minimum of 2 feet into competent earth materials, approximately 2 to 3 feet below existing ground surface, at the toe of proposed slope. Benching into firm materials was accomplished as the fill progressed up the gently sloping ground so that all fill materials were placed onto competent earth. The building area and 5 feet beyond was over excavated such that a minimum of 3 feet of fill exists beneath the building in the "cuf' area. CONCLUSIONS AND RECOMMENDATIONS CONCLUSIONS (1)T est resu~s indicate that fill placed as a result of this grading, to the horizontal and vertical limits as indicated, has been compacted to at least 90 percent relative compaction. A total of 5 tests were conducted and the resu~s are tabulated at the back of this report. The approximate locations of the field density tests are indicated on the Test Location Plan, Plate 1. (2) Fill Materials consisted of onsite silty sand. (3) Based on observation and classification, the matrix soils on the pad area appear to have an expansion potential of low. W. C. HOBBS, CONSUL lING ENGINEER 2.. 1- . . 'Mr. and Mrs. Shipley, Lot 158, Tr. 3929, Monte Verde Rd., Temecufa Page: 3 · Project No: 98056,2 (4) Groundwater was not encountered in any of the excavations during rough grading operations. 'RECOMMENDATIONS IThe recommendations contained herein are contingent upon W. C. Hobbs being retained to provide the following services in order to confirm design assumptions and review the field conditions of any excavations. Bearing Value and Footing Geometry 'A safe allowable bearim value for foundations embedded a minimum of 12 inches below lowest adjacent grade into competent native ground or compacted fill ground is 1500 pst. These values may be increased 100 pst per foot of depth and or width and should not exceed 1800 pst. Continuous footings should have a minimum width of 12 inches. The use of isolated column footings is permitted, and where utilized, should have a minimum embedment of 12 inches below lowest soil grade. Interior column footings need not be tied to perimeter footings, but should meet the minimum embedment criteria of 12". Minimum cover to daylight at slope face is 5 feet. Settlement The bearing value recommended above reflects a total settlement of 0.5" and a differential settlement of 0.5". This settlement is expected to occur during construction and as the loads are being applied. Where foundations are embedded into native ground, settlements can be substantially less. Concrete Slabs All concrete slabs on grade should be at least 4 inches thick. They should be underlain by 2 inches of sand or gravel. Areas that are to be carpeted or tiled, or where the intrusion of moisture is objectionable, should be underlain by 6 mil visqueen properly protected from puncture with an additional 1 inch of sand over it. This arrangement of materials would result in a profile downward of concrete, 1 inch of sand, 6 mil visqueen, 1 inch of sand and subgrade soil. Driveway slabs will not require underlayments. Contractors should be advise that when pouring during hot or windy weather conditions, they should provide large slabs with sufficiently deep weakened plane joints to inhibit the development of unsightly and irregular cracks. Clean onsite earth materials such as sand may be used for slab underlayments. w. C. HOBBS, CONSULIING ENGINEER .3 . . 'Mr. and Mrs. Shipley, Lot 158, Tr. 3929, Monte Verde Rd., Temecula Page: 4 Project No: 98056,2 'Recommendations, continued Reinforcement Continuous footings should be reinforced with a minimum of one number 4 steel bar placed at the ,top and one at the bottom. Slabs should be reinforced with a minimum of number 3 steel bars placed at the center of thickness at 18-inch centers both ways or welded wire fabric equivalent to 1 Ox1 0, 6/6 may be used. Selection is left to the Structural Engineer or Contractor. .LateraJ Loads The bearing value of the soil may be increased by one third for short duration loading (wind, seismic). Lateral loads may be resisted by passive forces developed along the sides of concrete footings or by friction along the bottom of concrete footings. The value of the passive resistance may be computed using an equivalent fluid density of 250 pcf. The total force should not exceed 2500 pst. A coefficient of friction of 0.35 may be used for the horizontal soil/concrete interface for resistance of lateral forces. If friction and passive forces are combined, then the passive values should be reduced by one third. A safety factor of 1.5 should be used in design. Retaining Walls Retaining walls should be designed to resist the active pressures summarized in the following table. The active pressure is normally calculated from the lowermost portion of the footing to the highest ground surface at the back of the wall. The active pressures indicated in the table are equivalent fluid densities. Walls that are not free to rotate or that are braced at the top should use active pressures that are 50% greater than those indicated in the table. RETAINING WALL DESIGN PRESSURES Slope of adiacent around Active Pressure Passive Pressure LEVEL(<5:1) 2:1 30pcf 450 pcf 250 pcf 38pcf These pressures are for retaining walls backfilled with non-rohesive, granular materials and provided with drainage devices such as weep holes or subdrains to prevent the build-up of ~Iydrostatic pressures beyond the design values. w. C. HOBBS, CONSULIING ENGINEER ., . . 'Mr. and Mrs. Shipley, Lot 158, Tr. 3929, Monte Verde Rd., Temecula Page: 5 Project No: 98056,2 : Recommendations, continued Fine Grading Fine grading of areas outside of the residence should be accomplished such that positive drainage exists away from all footings. Run-off should be conducted off the property in a non-erosive manner toward approved drainage devices. Construction Backfilling of any retaining walls should be observed by a soil engineer to assist the contractor in achieving the proper degree of compaction and desired moisture content. Also, the retaining wall subdrain system should be observed by the engineer prior to the backfill being placed. ~ is advisable to have the foundation excavations observed by a soil engineer prior the placement of construction materials in them as consequential changes and differences may exist throughout the fill and natural soils on the site. The ground left at the surface has very high erosion potential. It is strongly recommended that irrigation and vegetation or other approved means of erosion control be placed as soon as practical to minimize damage due to erosion. The opportunity to be of service is appreciated. Should questions or comments arise pertaining to this document, please contact the undersigned, in writing, for clarification. Respectfully Submitted, obbs, RCE 42265 Civil Engineer Distribution: Addressee (4) Attachments: Appendix A, Plate 1 w. C. HOBBS, CONSULIING ENGINEER 5' . . APPENDIX A SUMMARY OF RELD DENSITY TESTS Test Date Location Elev.* Typ Max M.C. Dry Rei Comments Num. ofT est of Test (feet) Crv D.o. (Qg) Dens. Com Remarks 1 11 0/98 PAD AREA 1128 A 126.0 10.5 117.0 93% Fill 2 11 0/98 PAD AREA 1130 A 126.0 11.0 116.0 92% Fill 3 10/98 PAD AREA 1132 A 126.0 11.5 115.5 92% Fill 4 1 0/98 PAD AREA 1134 A 126.0 10.0 118.0 94% Fill 5 1 0/98 PAD AREA 1135fp A 126.0 9.0 119.0 94% Fill Fie.ld Density Tests were conducted in accordance with ASTM 0 2937 fp denotes finished pad. * Below current pad elevation SUMMARY OF LABORATORY TEST RESULTS Curve Soil Maximum Optimum Letter Description Density oct Moisture % A Silty, SAND fn to 126.0 11.0 med., grey to brown(SM) M8)<imum density and optimum moisture determined in accordance with test method ASTM 0 1557-78. W. C. 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