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HomeMy WebLinkAboutCT 81-05; HOEHN HONDA; UPDATE GEOTECHNICAL INVESTIGATION; 1986-04-24I'. 3467 Kurtz Street California 92110 Woodward-Clyde Consultants (619) 224-2911 ENGINEERING April 24, 1986 Project No. 54167D-EC03 Architects Dominy Larson Carpenter 3111 Camino del Rio North San Diego, California 92108 Attention: Mr. Byron Anderson UPDATE GEOTECHNICAL INVESTIGATION HOEHN HONDA CARLSBAD TRACT 81-5, LOT 16 CARLSBAD, CALIFORNIA Gentlemen: This report presents the results of our update soil investigation at the subject site. The site is located on Lot 16 at the north end of Carlsbad Tract 81-5 north of Poinsettia Lane between Avenida Enemas and Interstate 5 in Carlsbad, California. To assist us in our study, we have discussed the project with you and have been provided a copy of a preliminary plan dated March 18, 1986 prepared by Klagge, Stevens & Associates. In addition, we have reviewed our records of work done previously on the site. Our previous reports are entitled: "Final Report of Engineering Observation of Grading and Testing of Compacted Fill, Lot 2 through 7 and 9 through 16, Carlsbad Tract 81-5, Carlsbad, California," dated December 13, 1974, and "Adden- dum Report, Additional Design Recommendations, Meister Property, Lot 16, Carlsbad Tract 81-5, Carlsbad California," dated June 20, 1985. We understand the proposed project will include: ° Regrading the site by lowering the east side by up to 5 feet and raising the west side by up to 5 feet. Three earth retaining walls are planned, one in the central portion of the site, one along the north and east sides of the site and one covering about one-third of the south side of the site. The maximum height of retaining wall will be about 14 feet. We understand that the wall will be constructed of con- crete block. ° The wood frame and stucco structures on the site will be up to two-stories high. Consulting Engineers. Geologists and Environmental Scientists Offices in Other Principal Cities qW Architects Domin•arson Carpenter Project No. 54167D-EC03 April 24, 1986 Page 2 . Woodward-Clyde Consultants PURPOSE OF INVESTIGATION The purpose of our investigation will be to provide information to assist you and your consultants in evaluating the property and for project de- sign. In particular, our investigation is designed to address: O General subsurface soil conditions; Conditions of areas to receive fill; O Presence and effect of expansive soils; O Grading and earthwork; Types and depths of foundations and allowable soil bearing pressure; and O Design lateral earth pressures for retaining walls. Review of Existing Reports The December 13, 1984 WCC report indicates that the lot is a cut-fill lot. Fill was placed on the western side of the lot up to about 4 feet in thick- ness. The fill was compacted to an indicated minimum of 90 percent rela- tive compaction. The cut area, roughly the eastern one-half of the site, has cuts ranging from about 7 feet in the northeast corner to zero at the southwest property corner. The cut-fill line extends from near the south- west property corner in a northerly direction to the north property line. Non-expansive fill was placed within 3 feet of rough grade on the fill portion of the lot. Soils exposed in the cut areas were also non-expansive. Field and Laboratory Investigation Our field investigation included making a visual geologic reconnaissance of the existing surface conditions, making 3 test pits on April 4, 1986 and obtaining representative soil samples. The pits were advanced to depths ranging from 5 to 8 feet. The approximate locations of the pits are shown on Figure 1. A Key to Logs is presented in Appendix A as Figure A-i. Final logs of the test pits are presented in Appendix A as Figure A-2 and A-3. The description of the logs are based on field logs, sample inspection, and laboratory tests. The results of laboratory tests are shown in Appendix B. The field investigation and laboratory testing programs are discussed in Appendices A and B. Architects Domin.arson Carpenter . Project No. 54167D-EC03 Woodward-Clyde Consultants April 24, 1986 Page 3 Site Conditions The site has been graded into a level lot pad which appears to be at the elevation as left in the 1984 grading operation. Cut slopes having slope ratios of approximately 2 to 1 (horizontal to vertical) and maximum heights of 7 feet exist on the north and east sides of the site. CONCLUSIONS AND RECOMMENDATIONS The conclusions and recommendations presented below are based on the results of our field investigation, review of our files and available plans, laboratory tests results, engineering analysis, and professional judgement. Grading We recommend that the proposed grading be performed in accordance with the attached Guide Specifications for Site Grading. We recommend that backfill placed in utility trenches located within 5 feet of a building and deeper than 12 inches, or backfill placed in any trench located 5 feet or more from a building and deeper than 5 feet, be placed in accordance with the above specifications. We also recommend that all grading be performed under the observation and testing services of our firm. Drainage We recommend that positive measures be taken to properly finish grade the lot after structures and other improvements are completed 'so that all drainage waters from the building pad and adjacent properties are directed off the site and away from foundations and floor slabs. Even when these measures have been taken, experience has shown that a shallow ground water or surface water condition can and may develop in areas where no such water condition existed prior to site development; this is particularly true where a substantial increase water infiltration results from landscap- ing irrigation. To further reduce the possibility of moisture related problems, we recom- mend that all landscaping and irrigation be kept as far away from the building perimeter as possible. Irrigation water, especially close to the building, should be kept to the minimum required level. We recommend that the ground surface in all areas be graded to slope away from the building foundations and floor slabs and that all runoff water be directed to proper drainage areas and not be allowed to pond. Foundations We recommend that conventional spread or continuous footings be designed for an allowable soil bearing pressure of 3,000 psf (total dead plus live load) at a depth below lowest adjacent rough grade of 18 inches. This is assuming that foundations are placed in properly compacted low expansion fill or undisturbed native soil. All footings should have a minimum width Architects Dominarson Carpenter Project No. 54167D-EC03 April 24, 1986 Page 4 . Woodward.Clyde Consultants of 12 inches. The bearing pressure may be increased by one third for loads that include wind or seismic forces. We recommend that all continu- ous footings be reinforced top and bottom with at least one No. 4 rebar. Retaining Walls It is recommend that retaining walls not restrained from movement at the top and required to support lateral earth pressures due to differential soil height be designed for an equivalent fluid pressure of 35 pcf. This pressure assumes the wall has a level backfill composed of granular soil available on site, and drainage is provided behind the wall to prevent build-up of hydrostatic pressures. To resist lateral loads, it is recommended that an equivalent fluid passive pressure of 350 pcf be used for design for foundations founded in natural undisturbed native soils. As an alternate method to resistance sliding, friction factor of 0.35 for concrete against soil may be used for design in undisturbed native soils. If passive pressures and friction are used in combination, it is recommend- ed that the friction factor be reduced to 0.3 for native and fill soils. Concrete should be poured neat against the undisturbed dense to very dense formational sands to develop full design values of passive sliding friction resistance. UNCERTAINTY AND LIMITATIONS We have observed only a very small portion of the pertinent soil and conditions on the site. The recommendations made herein are based on the assumption that soil conditions do not deviate appreciably from those found during our field investigation. We recommend that Woodward-Clyde Con- sultants review the foundation and grading plans to verify that the intent of the recommendations presented herein has been properly interpreted and incorporated into the contract documents. We further recommend that Woodward-Clyde Consultants observe the site grading, subgrade prepara- tion under concrete slabs and paved areas, and foundation excavations to verify that site conditions are as anticipated or to provide revised rec- ommendations if necessary. If the plans for site development are changed, or if variations or undesirable geotechnical conditions are encountered during construction, we should be consulted for further recommendations. This report is intended for design purposes only and may not be sufficient to prepare an accurate bid. California, including Carlsbad, is an area of high seismic risk. It is generally considered economically unfeasible to build a totally earthquake-resistant project; it is, therefore, possible that a large or nearby earthquake could cause damage at the site. Geotechnical engineering and the geologic sciences are characterized by uncertainty. Professional judgements presented herein are based partly on our understanding of the proposed construction, and partly on our general Architects Dominarson Carpenter Project No. 54167D-EC03 Woodward-Clyde Consultants April 24, 1986 Page experience. Our engineering work and judgements rendered meet current professional standards; we do not guarantee the performance of the project in any respect. Inspection services allow the testing of only a small percentage of the fill placed at the site. Contractual arrangements with the grading contractor should contain the provision that he is responsible for excavating, placing, and compacting fill in accordance with project specifications. Inspection by the geotechnical engineer during grading should not relieve the grading contractor of his primary responsibility to perform all work in accordance with the specifications. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations, and we can not be respon- sible for the safety of personnel other than our own on the site; the safety of others is the responsibility of the contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. If you have any questions, please give us a call. Very truly yours, WOODWARD-CLYDE CONSULTANTS Joseph G. Kocherhans R.E. 23060 JGK/sar Attachments (6) Architects Dominy Larson Carpenter N I N _J PROPOSED " RETAINING \\\ WALL PARKING AREA \. \ /Site Boundary 31-5 1-75 1\ PROPOSED BUILDING)\ 12 \ PROPOSED -, RETAINING WALL / / 3 / PARKING AREA I . / I -- 2 0 20 110 I— Graphic Scale (Feet) SITE PLAN HOEHN HONDA AWN DY ch I CNECXEO SY PIOUDS NO: 1 .,..TE: 11-22-86 I PDOJCTNO: 511167DECO3 Dues W000WARO-CLYOE CONSULTANTS Project No. 54190-EC03 S. Woodward-Clyde Consultants Appendix A Three exploratory test pits were advanced at the approximate locations shown on the Site Plan (Figure 1). The pits were dug on April 4, 1986 with a 24 inch bucket backhoe under the direction of a geologist from our firm. Samples of the soils encountered were obtained from the test pits in sacks or in thin metal tubs (hand drive). The tube samples were sealed to preserve the natural moisture content of the sample. The samples were bought to the laboratory for examination and testing. A-i Location Boring Number Elevation IDEPTH IN TESTOATA I'OTHER1LN SAMPLE J SOIL DESCRIPTION I _ FEET TESTS NIBER 12 110 65 Very dense, moist, brown silty sand (SM) NOTES ON FIELD INVESTIGATION WATER LEVEL At time of drilling or as indicated. SOIL CLASSIFICATION - Soil Classifications are based on the Unified Soil Classification System and include color, moisture and consistency. Field descriptions have been modified to reflect results of laboratory analyses where appropriate. DISTURBED SAMPLE LOCATION Obtained by collecting the auger cuttings in a plastic or cloth bag. DRIVE SAMPLE LOCATION MODIFIED CALIFORNIA SAMPLER Sample with recorded blows per foot was obtained with a Modified California drive sampler (2' inside diameter, 2.5 outside diameter) lined with sample tubes. The sampler was driven into the soil at the bottom of the hole with a 140 pound hammer falling 30 inches. STANDARD PENETRATION SAMPLER Sample with recorded blows per foot was obtained using a standard spilt spoon sampler (1 Inside diameter, 2" outside diameter). The sampler was driven into the soil at the bottom of the hole with a 10 pound hammer falling 30 Inches and the sample placed In a plastic bag. INDICATES SAMPLE TESTED FOR OTHER PROPERTIES GS - Grain Size Distribution CT - Consolidation Test LC - Laboratory Compaction UCS - Unconfined Compression Test Test SDS - Slow Direct Shear Test P1 - Atterberg Limits Test 05— Direct Shear Test ST - Loaded Swell Test TX— Triaxial Compression Test CC— Confined Compression 1R'— R—Value Test NOTE: In this column the results of these tests may be recorded where applicable. BLOW COUNT Number of blows needed to advance sampler one foot or as indicated. DRY DENSITY See Note 2. Pounds per Cubic Foot MOISTURE CONTENT Percent of Dry Weight 1. REFUSAL indicates the inability to extend excavation practically, with equipment being u.ed in the investigation. KEY TO LOGS HOEHN HONDA DRAWN BY: chj CHECKED BY: I PROJECT NO: 54167D—EC03 J DATE: 4-22-86 FIGURE NO: A—i W000WARD-CLYDE CONSULTANTS •: Test Pit 1 n-c P1 •)' I DEPTH I TEST DATA d*OT~HEIRI1 .BCT SL . SOIL DESCRIPTION I MC DD SAMPLEIN FEET 5 10 15 Medium dense, moist, brown, silty sand (SM) with trace clay PLEISTOCENE TERRACE DEPOSITS Medium dense, moist, light brown and light gray brown, poorly graded band (SP) PLEISTOCENE TERRACE DEPOSITS Dense, moist, dark gray to brown, silty sand (SM) PLEISTOCENE TERRACE -DEPOSITS Bottom of Hole Test Pit 2 I DEPTH I IN I TEST DATA J*OTHERI SAMPLE I SOIL DESCRIPTION 1 MC OD BC I FEET TESTS NUMBER ( 5-1 26 I 95 10 2-1 E Medium dense, moist, light brown and light gray to brown, silty sand (SM) PLEISTOCENE TERRACE DEPOSITS Medium dense, moist, dark gray to brown, 2-2 = : poorly graded sand (SP). PLEISTOCENE TERRACE DEPOSITS Bottom of Hole 15] I 1 I For description of symbols, see Figure A—i LOG OF TEST PITS 1 AND 2 HOEHN HONDA DRAWN BY: ch I CHECKED BY)'14I PROJECT NO: 54167D—EC03 DATE: 4-22-86 FIGURE NO: A-2 WOODWARD-CLYDE CONSULTANTS 5 10 15 Test Pit 3 I DEPTH I IN I TEST DATA 'OTHERI F SAMPLE I SOIL DESCRIPTION MC DD BC FEET TESTS NUMBER *For description of symbols, see Figure A-i LOG OF TEST PIT 3 HOEHN HONDA DRAWN BY: ch I CHECKED BYI PROJECT NO: 54167DEC03 I DATE: 4-22-86 FIGURE NO: A-3 W000WARD.CLYDE CONSULTANTS Project No. 541-EC03 Woodward-Clyde Consultants APPENDIX B LABORATORY TESTS The materials observed in the borings were visually classified and evalu- ated with respect to strength, swelling, and compressibility characteris- tics; dry density; and moisture content. The classifications were substan- tiated by performing grain size analyses on representative samples of the soils. The strength of the soils was evaluated by considering the density and moisture content of the samples and results of the slow direct shear test. The results of the moisture content and dry density tests are shown with the penetration resistance of the sampler at the corresponding location on the logs, Figure A-2 and A-3. The results of the grain size analyses are shown in Figure B-i and slow direct shear test results are shown in Figure B-2. : fl SAND SILT and CLAY 1 I GRAVEL Coarse I Fine ICoarsel Med i um I Fine Mesh Op ening Ins Sieve Sizes Hydrometer An I, ----- — an _____ _________________________ .._..__•________ ____________ . .-- .________ ____i..___ — 70 60 0 zo 30 C/) C,) 50 w 30 20 _____________________ •1 - -- --._________ 1 00 5s 10.0' 0.01 0.005 0.001 GRAIN SIZE IN MILLIMETERS I SAMPLE CLASSIFICATION AND SYMBOL *LL *PI o_1-3 Poorlygradedsand (SP) --- C) 2-2 Poorlygradedsand(SP) 3-2 Poorly _gradedsand _(SP) *LL - Liquid Limit PI - Plasticity Index I GRAIN SIZE DISTRIBUTION CURVES I HOEHN HONDA LDRAWNBY:ch _CHECKED BV:7I_PROJECTNo:54167D-ECO3 _ DATE: 4-22-86 J_ FIGURE NO:Bl W000WARD-CLYDE CONSULTANTS IC C-GS-76 ]sees 9830 8000 7800 (.0 Ln 8000 I- In 5000 4000 In 3200 2000 (002 0 STRESS/STRAIN GRAPH 10000 9000 8020 7000 6000 U, Ln 5000 I- ' 4000 Cr LLJ 3000 U, 2000 (000 (I DEFORMATION, inches (U (U - (U (' r (0 CD (U (U NORMAL STRESS,psf SAMPLE DATA Sample/Classification Sample 1-3, Light brown to tan, silty sand (SM) Specimen Number 1 2 Height, inches .812 .812 Diameter, inches 1.94 1.94 Initial Dry Density, pcf 94 95 Initial Moisture Content, % 8 7 Initial Saturation, % 28 26 Final Dry Density, pcf 96 98 Final Moisture Content, % 24 23 Final Saturation, % 87 89 Normal Stress, psf 4116.5 8185.9 TEST DATA Type of Test: Slow Direct Shear Test Angle of Friction, Effective 0' = 300 Cohesion, Effective C' = 1075 psf Rate of Shear, in/mm .00028800 r SLOW DIRECT SHEAR TEST I HOEHN HONDA [DRAWN BY: chiCHECKED BY:,4XJPROJECT NO: 54167D—ECO3 IDATE: 4-2286 FIGURE NO: B-2 W000WARD-CLYDE CONSULTANTS Project No. 541610--EC03 Woodward. Clyde Consultants GUIDE SPECIFICATIONS FOR SITE GRADING Project: Hoehn Honda, Tract 81-5, Lot 16 1. GENERAL 1.1 The work of the Contractor covered by this specification consists of furnishing labor and equipment and performing all operations necessary to remove deleterious and undesirable materials from areas of grading, to properly prepare areas to receive fill, and to excavate and fill to the lines and grades shown on the plans or as directed in writing by the Civil Engineer (Architect). 1.2 The Contractor shall perform the work in strict accordance with these specifications and he shall be responsible for the quality of the finished product notwithstanding the fact that the grading work may be inspected and tests made by a Soil Engineer. 1.3 Deviations from these specifications will be permitted only upon written authorization from the Soil Engineer. An update geotechnical investigation has been made for this project; any recommendations made in the report of the soil investigation or subsequent reports concerning grading aspects shall become an addendum to these specifications. DEFINITIONS 2.1 Contractor shall mean the contractor performing the grading work. 2.2 Owner shall mean the owner of the property or the party on whose behalf the grading.work is being performed and who has contracted with the Contractor to have the grading performed. 2.3 Civil Engineer (Architect) shall mean the engineer (architect) who has prepared the grading plans and who is the Owners' representative concerning the configuration, quantities and dimensions of the grading and who usually sets basic surveying data at the site for the Contractor's conformance. 2.4 Soil Engineer shall mean a duly licensed Civil Engineer, qualified in soil engineering, who is responsible for having qualified representatives on site to observe and test the Contractor's work for conformance with these specifications. Project No. 541 -ECO3 Woodward-Clyde Consultants OBSERVATION AND TESTING 3.1 The Soil Engineer shall be the Owner's representative to observe and make tests during the fill foundation preparation, filling and compacting operations. As a general rule, no more than 2 feet of fill in vertical elevation shall be placed without at least one field density test being made within that interval. 3.2 The Soil Engineer shall make random field density tests of the com- pacted fill to provide a basis for expressing his opinion as to whether the fill materiel is compacted as specified. The basis for his opinion that the fill material has been compacted to at least the minimum relative compaction specified, shall be that no tests in compacted or recompacted areas indicate a relative compaction of less than that specified. Density tests shall be made in the compacted materials below any disturbed surface. When these tests indicate that the density of any layer of fill, or portion thereof, is below the specified density, the particular layer or area represented by the test shall be reworked until the speciried density has been achieved. 3.3 Testing shall.conform to the following standards as pertinent: O Field Density Test, Nuclear Method - ASTM D2922-81," Density of Soil and Soil-Aggregate In-Place by Nuclear Methods (Shallow Depth)". O Field Density Test, Sand-Cone Method - ASTM D1556-82, "Density of Soil In-Place by the Sand-Cone Method". O Laboratory Compaction Test - ASTM D1557-78, "Moisture-Density Relations of Scils and Soil-Aggregate Mixture Using a 10-lb. Hammer and 18-inch Drops". CLEARING AND PREPARING AREAS TO BE FILLED 4.1 All trees, brush, grass, and other objectionable material shall be collected from areas to receive fill, piled and disposed of off-site by the Contractor so as to leave the areas that have been cleared with a neat and finished appearance free from debris. 4.2 All loose or porous soils shall be removed or compacted as specified for fill. The depth of removal and recompaction shall be approved in the field by a representative of the Soil Engineer. Prior to placing fill, the surface to be filled shall be free from uneven features that would tend to prevent uniform compaction by the equipment to be used. It shall then be plowed or scarified to a minimum depth of 6 inches. -2- Project No. 5416*-EC03 . Woodward-Clyde Consultants 4.3 Where fills are constructed on hillsides or slopes; topsoil, slopewash and colluvium shall be removed. Where the exposed slope is steeper than 6 horizontal to 1 vertical, or where specified by the Soil Engineer, the slope of the original ground on which the fill is to be placed shall be stepped or keyed by the Contractor as shown on the figure below. The steps shall extend completely through the soil mantle and into the underlying formational materials or, where formational material is not present, into compact ground. TYPICAL KEY Strip as specified Original ground - M Slope ratio = N Fill Slope to be such that sloughing or sliding does not occur Remove, all topsoil, slopewash, colluvium and other loose soils I- See note Varies A See note NOTES: The outside edge of bottom key "A" shall be below topsoil or loose surface material and in no event less than 2 feet in depth. The minimum width of "B" Bench shall be 2 feet wider than the compaction equipment, and not less than 10 feet. Project No. 541 -ECO3 S Woodward-Clyde Consultants 4.4 After the foundation for the fill has been cleared, plowed or scarified, it shall be disced or bladed by the Contractor until it is uniform and free from large clods, brought to the specified moisture content, and compacted as specified for fill. MATERIALS 5.1 Materials for compacted fill shall consist of any soil imported or excavated from the cut areas. The soil shall contain no rocks or hard lumps greater than 6 inches in maximum dimension and shall contain at least 40% of material smaller than I inch in size. Material of a perishable, spongy, or otherwise improper nature shall not be used in fills. 5.2 Material placed within 36 inches of rough grade shall be select material that contains no rocks or- hard lumps greater than 6 inches in maximum dimension and that has an Expansion Index of 30 or less when tested in accordance with UBC Standard 29-2. 5.3 Representative samples of materials to be used for fill shall be tested in the laboratory by the Soil Engineer in order to determine at least the maximum density, optimum moisture content, classification of the rail and expansion index as required. 5.4 During grading operations, soil types other than those analyzed in the report of the update geotechnical investigation may be encountered by the Contractor. The Soil Engineer shall be consulted to determine the suitability of these soils. COMPACTION EQUIPMENT 6.1 Compaction shall be accomplished by sheepsfoot rollers, vibratory rollers, multiple-wheel pneumatic-tired rollers, or other types of acceptable compaction equipment. Equipment shall be of such a design that it will be capable of compacting the fill to the specified density at the specified moisture content. PLACING, SPREADING, AND COMPACTION OF FILL MATERIAL 7.1 After each layer has been placed, mixed, and spread evenly, it shall be thoroughly compacted by the Contractor to. a relative compaction that is indicated by test to be not less than 90 percent. Relative compaction is defined as the ratio (expressed in percent) of the in-place dry density of the compacted fill divided by the maximum laboratory dry density determined in accordance with the ASTM Test No. D1557-78, or other density test methods that will obtain equivalent results. Unless otherwise specified, fill material shall be compacted by the contractor while at a moisture content at or above the optimum moisture content determined in accordance with the above test method. Project No. 541•-EC03 Woodward-Clyde Consultants 7.2 The fill material shall be placed by the Contractor in layers that, when compacted, shall not exceed 6 inches. Each layer shall be spread evenly and shall be thoroughly mixed during the spreading to obtain uniformity of moisture and material in each layer. The entire fill shall be constructed as a unit, in nearly level lifts starting up from the lowest area to receive fill. Compaction shall be continuous over the entire area, and the equipment shall make sufficient uniform trips so that the desired density has been obtained throughout the entire fill. Rock materials greater than 6 inches in maximum dimension shall be distributed in such a manner that they are completely surrounded by compacted fines; nesting of rocks shall not be permitted. 7.3 When the moisture content of the fill material is below that specified by the Soil Engineer, water shall be added by the Contractor until the moisture content is as specified. 7.4 When the moisture content of the fill material is above that specified by the Soil Engineer or too wet to achieve proper compaction, the fill material shall be aerated by the Contractor by blading, mixing, or other satisfactory methods until the moisture content is as required to permit compaction. 7.5 Soils with higher expansion potential than specified may be used in fills below a depth of 36 inches from design rough grade and shall be compacted at a moisture content greater than the optimum moisture content for the material. 7.6 Properly compacted fill shall extend to the design surface of fill slopes. The surface of fill slopes shall be compacted as necessary and there shall be no loose soil on the slopes. 8. PROTECTION OF WORK 8.1 During construction the Contractor shall properly grade all excavated surfaces to provide positive drainage and prevent ponding of water. He shall control surface water to avoid damage to adjoining properties or to finished work on the site. The Contractor shall take remedial measures to prevent erosion of freshly graded areas and until such time as permanent drainage and erosion control features have been installed. 8.2 After completion of grading and when the Soil Engineer has finished his observation of the work, no further excavation or filling shall be done except under the observation of the Soil Engineer. -5-