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HomeMy WebLinkAbout; La Costa Meadows Unit 1 Luciernaga Court; Soils Report; 1989-06-15LAKESHORE Engineering, Inc. Consulting Civil Engineering and Geologists - GEOTECHNICAL INVESTIGATION PROPOSED RESIDENTIAL TRACT - - - - - - - LOTS 194 Ei 195 LUCIERNAGA COURT, UNIT 1 LA COSTA MEADOWS SAN DIEGO COUNTY, CALIFORNIA FOR LOUIS BIKADI PROJECT NO: 89-055P.I. JUNE 15, 1989 -RECEIVED JUL 18 1989 ENGINEERING DEPT. LIBRARY City of Carl&ad 2075 Las Palmas Drive Carlsbad, CA92009-4859 -- a.h-5, n, ( :ITY ui- wnwBAD ~~~ p~2. Servi kes ?llSA7 Railmarl Cvn~ Rd l Rnx 7 l Canvnn I aka CA 97RRtl l 1714) 744~3011 June 15, 1989 Project No: 89-055 Client: Mr. Louis Bikadi . P.O. Box 4082 Canyon Lake, CA 92380 (619) 756-9359 Subject: Geotechnical Investigation for Residential Tract Lots 194 and 195 Luciernaga Court, Unit 1 La Costa Meadows, San Diego County, CA Gentlemen: INTRODUCTION This report presents the findings and conclusions of a soils and foundation investigation for the proposed residential tract, located at the subject site. The purpose of this investigation was to (1) evaluate the foundation materials and subsurface conditions underlying the site, and (2) provide pertinent recommendations for the proposed development of the site. The investigation included the following scope of work: Performed exploratory trenchs adjacent to the proposed building iads, to determine subsurface conditions and provide soil samples for laboratory testing (Appendix A). 0 Laboratory testing of representative soil samples to evaluate their engineering properties. Laboratory test results are presented in Appendix B. 0 Engineering and geologic analyses for foundations and necessary earthwork. PROPOSED DEVELOPMENT Planned development of the subject site will consist of dividing the property into four (4) parts, as shown on Plate 1. Each subdivision will be graded for a single family residence with appurtenant grounds and facilities. The proposed pad areas are shown on Plate 1. The planned residences are two story with attached garages and are of conventional woodframe construction. Typical wall loads of 4,500 pounds per lineal foot, and maximum column loads of 15 kips have been assumed for engineering analysis. The grading will consist of a cut and fill operations to provide room for two level pads on moderately sloping, hill side terrain above existing level ground, which will be developed for a lower set of two level pads. The existing back, cut slope rises at a rate of approximately 3 l/2 / 1 (H.V.). Development plans call for increasing the rate of slope to 2/l (H.V.), behind the upper two pads and placing a six foot high retaining wall at the toe of the cut slope. - - - - - - - - - - - - - - - - .- - - .- - - - - .- June 15, 1989 Project No: 89-055 Page Two SITE INVESTIGATION The site investigation consists of surficial reconnaissance mapping and subsurface exploration. The reconnaissance mapping included observation of general surface conditions and irregularities of the ground and sediments. The subsurface exploration included trenching of exploratory backhoe pits to a maximum depth of 6 feet. The shallow depths are minimal because of the occurrence of hard bedrock under only thin coverings of soil. Test pit locations are shown on Plate 1. Materials encountered during subsurface exploration were logged by the field geologist and technician and are presented in Appendix A. On-site density tests were performed in the exploration trenches at various depths. Site Description The site occupies 1.4 acres and is located at the head of Luciernaga Court about 3 l/2 miles east of the ocean, northeast of the head of Batiquitos Lagoon. The borders of the property, are Luciernaga Street on the north, and undeveloped residential ground in the other direction. Access to the site is by way of Luciernaga Street , which runs along the property from east to west. The approximate site location with respect to streets, regional topography and landmarks, is shown on Figure 1. The ground at the subject site occupies level ground, artificially filled at the head of Luciernaga Court and~extends eastward onto hillside terrain which slopes moderately westward at a present rate of about 3 l/2 / l/ (H.V.). The slopes are covered with thin soils and a native growth of annual grasses and chappard-like brush. Drainage lines across the slope are poorly developed and short. No creek bed throughways cross the property. The elevation is between 200 and 300 feet. The existing back (eastern) slope (hillside) is about 50 feet high. No structures now exist on the property . Topographically, the site is located in the lower slope area of the hillside terrain, just back from Encinitas. The natural ground surface is even and moderatly smooth. Drainage in the property is mostly by sheet wash and direct infiltraction. The strength of this activity appears slight. Active surface incision and deposition of sludge soils is not observable. I I I ( I I I I / ! - - - - - KelD / mud S”d rocw sand rn”d A South Oceansiae -- -A- I n Maa cOs”ourck Cali?ornia Geologic 7 s%z two Map FQ&B, Santa-Ana’ Sheet Y mud mud ~$caile: 2.6 mi./inch 1 Fig. 2 dq%?y<& Danger area @Id* 30’ - - Fault Map Coastal Southern Ca (Source: ZlOmy, and Others, 1954). Scale: 6 mi./inch - - - - .,- .- - .-. - - - - .~ - - - - - - June 15, 1989 Project No: 89-055 Page Three GEOLOGY Geologic Setting The proposed development is located in the Peninsular Ranges Province of Southern California, which is characterized by a basement complex of Mesazoic, Paleozoic, and Precambrain granitoid rocks FA&%% and prebatholithic metasedimentary and volcanic rocks, overlain in costal areas in many places by tertiary, sedimentary formations. The area is moderately, seismically active, owing to the existance of offshore extensions of the Rose Canyon Fault. Bedrock Bedrock is exposed at shallow depths along the foot of the eastern, hillside part of the property, within the borders of the proposed development. These rocks are hard, folliated types, which are mapped as "Jura-Triassic metavolcanic rocks" (JTRV) on maps of California Geologic map folio. These rocks are strongly silicified in this area and are very tough, aphanitic (very finely crystalline) and vary in color from shades of gray to slightly green. The layering strikes approximately north south and dips about 50 degrees to the east, into the hill. Alluvium and Soil Soil, colluvium, and hill creep overlie bedrock l/2 feet along the foot of the hillside. In the of Luciernaga Court, artificial soils have been to a depth of up to 3 flat area at the head added above a native soils are granular from the local native sequence of alluvial materials. The artificial silts and silty sands and were probably derived materials. These artificial fills are about 3 feet deep. The overall thickness of artificial and native materials in the flat area is not known, but probably is in excess of 10 feet. Soils at the surface generally appear low in expansion potential. Groundwater Groundwater was not encountered within the property during excavation of the trenches. The general topography suggests that the level is at least 50 feet below the surface elevation at the property location. Flooding The subject site does not lie within any major drainage section and is over 100 feet above mean sea level. - - - - - - - .- .- - - - June 15, 1989 Project No: 89-055 Page Four Faults and Seismicity The area of the subject site is located approximately 6 miles east of possible offshore extensions of the Rose Canyon Fault. However, no faults have been mapped passing through the subject site, itself, or mapped so that they may be projected through the site(see references). The current work did not determine the presence of any faults. Recent work suggests that a figure of M6.5 is probable for the Rose Canyon Fault, as a maximum credible level of shaking for ordinary planning and design purposes. Such an event on a nearby fault strand could produce maximum rock accelerations of about 0.4Og and maximum repeatable accelerations of around 2.5g to 3.Og. Seismic parameters for the Rose Canyon Fault, which may be anticipated are as follows: Richter Repeatable Ground Predominant Period Duration of Magnitude Acceleration Value of Seismic Waves Strong Ground Cm) (9) (set) Shaking (set) 6.5 0.27 0.35 18 These accelerations should not be used as design values for the Uniform Building Code formula. They should be considered as an aid in the evaluation of the structural design of the permanent structures. SECONDARY EFFECTS Secondary effects of strong ground motion includes induced subsidence, flooding and induced landsliding. Potential for induced subsidence is considered low due to the lack of a deep alluvial basin under the site (e.g. bedrock generally at a few feet). Similarly the potential for induced flooding is low due to the sties location away from active drainage and open water. Induced landsliding is probably not a hazard, because of bedrock conditions at the site. Rocks are hard and cohesive, and dip opposite to the direction of fill slope. No landslides are mapped in the area. No loose, hummucky configurations were observed in this study. In most historic California earthquakes, tectonic ground rupture directly attributable to faulting has been limited generally to a zone within a few hundred feet of the fault trace. Thus, for the subject site, movement along known active faults, would not be likely to produce tectonic ground rupture on the site. The possibility for sympathetic movement to occur on secondary or tertiary faults, which may underlie the site at depth, is considered remote. - - - .- - - - - - June 15, 1989 Project No: 89-055 Page Six Rippability No difficulty was experienced dur anticipated that earthwork can be earthmoving equipment and methods sufficient. No blasting should be CONCLUSIONS AND RECOMMENDATIONS GENERAL ing the trenching operations. It is accomplished with standard . D-6 or D-9 equipment will be required. From a soil and foundation engineering standpoint, the site will be suitable for residential development, provided the conclusions and recommendations presented in this report are incorporated in the design considerations, project plans and specifications. GRADING AND EARTBWORX GENERAL Site grading will be required to provide: 1) nearly level building pads; 2) suitable foundation conditions to support the proposed residential structures; 3) adequate surface gradients for control of water runoffiand 4) excavation into native soils and/or compacted fill to accommodate the installation of foundations and utility systems. After the areas have been stripped and disposed of all vegetation, the excavated on-site soils will be considered satisfactory for reuse in the construction of site fills. The existing native soils, in the areas of proposed building pads (Buildings No. 1 & 2) should be reworked to a depth of at least 48 inches in the pad areas, and densified to at least 90 percent of the maximum laboratory density as determined by the A.S.T.M. D1557-78 compaction method. All non-engineered fills should be excavated and recompacted under engineering observation and testing. If the existing grade is to be raised at least 36 inches with imported fill, only the upper 24 inches of the subgrade exposed by stripping or excavation need to be reworked. For proposed building numbers 3 & 4, it anticipated that the structure will be founded on competent bedrock material. Any surface or subsurface grading obstructions, such as utility lines encountered during.grading should be brought immediately to the attention of the Soils Engineer, so as to observe proper exposure, removal and/or relocation as directed. No underground obstructions nor facilities should remain in any structural areas which will receive compacted fill, building foundations, concrete slabs and pavements. Depressions and/or cavities created as a result of the removal of the grading obstruction fill materials and chmpacted under should be pro~en~,lge~~~~~iaBseedr~~~Ci)loaub~Bble testing. - - - .- - - - - - June 15, 1989 Project No: 89-055 Page Seven All imported soils should be approved by the Consulting Engineer prior to use. Caution should be exercised to prevent mixing of select native or imported materials with soils containing debris and/or organic matter. Any objectionable substance, as determined by the Consulting Engineer, should be stripped and removed from the property or stock piled for landscaping purposes. All structural fills constructed in areas of proposed building pads and/or pavements should be densified in conformance weith appropriate grading code but shall not be less than 90 percent relative compaction, by mechanical means only. Shrinkage and Subsidence In planning the proposed grading operations, we recommend that a shrinkage factor of about 15 to 20 percent be used for the overexcavation and recompaction of the superadjacent materials. That 1.15 to 1.20 yards of in-place material will be required to yield is6 cubic yards of properly densified fill, without wasting, at 90 percent relative compaction. In addition, approximately 0.30 feet of subsidence should be anticipated due to the reworking of surficial soils. Excavation Conditions Excavation of on-site materials should be readily accomplished with standard earthmoving or trenching equipment. The walls of temporary construction trenches should stand nearly vertical, provided the total depth does not exceed 5 feet. Shoring of excavation walls or flattening of slopes is expected to be required, if greater depths are necessary. For deeper cuts, slopes should not be made steeper than 1:l horizontal:vertical. All work associated with trench shoring must conform to the State of California Safety Code. Native organic free soils may be utilized for trench backfill. Flooding of the trench backfill may be permitted, provided both the backfill and the native materials have a minimum sand equivalent of 30 and the required relative compaction can be achieved. GRADING CONTROL All grading and earthwork including trench backfill should be performed under the observation and testing of the Consulting Engineer for proper subgrade preparation, selection of satisfactory materials, placement and compaction of all structural fill. Sufficient notification prior to stripping and earthwork construction is essential in order that the work will be adeqately observed and tested. In order for us to provide a written opinion as to adequacy of soil compaction and trench backfill, the entire operations,most importantly at the time of trench backfill, should be performed under our observation and testing. - - .-~ .- .- - - - - - - - .- June 15, 1989 Project No: 89-055 Page Eight Footings The proposed residential developments may be supported on conventional spread footings established in compacted fill. These footings may be designed for an allowable bearing value of 1000 pounds per square foot. This design value may be increased by one third, if the Structural Engineer takes into consideration short duration structural loading conditions, such as induced by wind or seismic forces. Footings should be founded at least 12 and 18 inches below lowest adjacent ground surface for one and/or two story structures respectively. All continuous foundations should be reinforced consistent with the recommendations of the Structural Engineer or Architect. Settlements Total settlements due to structural,loads should not be a design factor as they should be less than 0.5 inches. LATERAL CAPACITY For design, resistance to lateral loads can be. assumed to be provided by friction acting at the base of foundations and by passive earth pressure and may be combined without reduction. If passive earth pressure is used, it is important that backfill should be placed under engineering observation and testing. A c&ficient of friction of 0.25 may be assumed with the dead load forces. An allowable lateral passive earth pressure of 150 of depth may be used for the sides of undisturbed or recompacted soil. pounds per square foot per footings poured against foot The lateral bearing values indicatied above are for the total of - - dead and frequently applied live loads. Ir normal code requirements are used for seismic design, -the values may be increased by l/3 for short durations of loading which include the effect of wind or seismic forces. Expansive Soils Subgrade materials are considered to be non to low in expansion potential. We recommend that slab subgrade should be evaluated for expansive soil characteristics near the completion of rough grading, and reinforcement measures can be forwarded. - - June 15, 1989 Project No: 89-055 Page Nine SLABS-ON-GRADE Concrete floor slabs may be directly supported on the properly prepared subgrade; if necessary, preparation shall include proof-rolling just prior to construction to provide a firm unyielding subgrade. Subgrade materials are considered to be low in expansive potential. Slab subgrade should be re-evaluated at the conclusion of rough grading. If a floor covering that would be critically affected by moisture, such as vinyl tile, is to be used, slabs should be protected by a plastic vapor barrier of six-mil thickness. The sheeting should be covered with at least two inchs of sand to prevent punctures and to aid in the concrete cure. - For estimating purposes and in order to minimize crack size, the concrete floor slabs should be reinforced as follows: 1) Concrete floor slab should be at least 4 inches thick actual. - 2) The floor slab should be reinforced with at least 6" x 6" w 1.4/ w 1.4 welded wire mesh or equivalent bar reinforcing and installed at - Mid-height. APPURTENANT STRUCTURES - - Construction of any proposed appurtenant structures such as swimming pools, gazabos, decks, etc. should be reviewed by a consulting engineer in order to verify expansive soil conditions, after rough grading is completed. In this regard, any supplemental recommendations can be forwarded without delay. - - - SLOPES AND RETAINING WALLS At the time of the preparation of this report, proposed grading plans for the subject property are tentative. It is our understanding that slopes will be constructed at 2:l (H/V) to a height of feet. Retaining walls six feet high will be placed at the toe of the prepared back (east) slope, between the upper pad levels and the hillside area. Drainage Positive drainage should be provided around the perimeter of all structures to minimize water infiltrating into the underlying soils. Finish subgrade adjacent to exterior footings should be sloped down and away to facilitate surface drainage. All drainage should be directed off-site to the street via non-erosive devices. June 15, 1989 Project No: 89-055 Page Ten The client should be made aware of the potential problems which may develop when drainage is altered through construction of retaining walls or paved walkways, landscaping and patios. Ponded water, leaking irrigation systems, overwatering or other conditions which could lead to ground saturation must be avoided especially in the areas immediately adjacent from structures (5ft. min.). Footing Excavations All foundation excavations should be inspected and approved by the Soil Engineer prior to placement of forms, reinforcement, or concrete. Materials from footing excavations should not be spread in pavement subgrades or slab-on-grade areas unless they are compacted and tested. GENERAL INFORMATION The findings and recommendations of this report were prepared in accordance with generally accepted professional engineering, principles and practice in the fields of Soil and Foundation engineering. This warranty is in lieu of all other warranties, either express of implied. This report presents recommendations pertaining to the subject site based on the assumption that the subsurface conditions do not deviate appreciably from those disclosed by our exploratory trenches. The possibility of different local soil conditions cannot be discounted. It is the responsibility of the owner to bring any deviations or unexpected conditions observed during construction to the attention of the Engineer. In this way, any required supplemental recommendations can be made with a minimum of delay to the ,project. This firm does not practice or consult in the field of safety engineering. We do not direct the contractor's operations and cannot be responsible for the safety of other than our own personnel on the site. The contractor should notify the owner if he considers that construction safety of any of the recommended actions presented in this report may be improved. Professional judgments represented in this report are based partly on evaluations of the technical information gathered partly on our understanding of the proposed construction, and partly on our general experience in the geotechnical field. We do not guarantee the performance of the project in any respect only that our engineering work and judgment rendered meet the standard of care of our profession at this time. If conditions are encountered during the design, approval by the governing agencies, and/or the construction period, that appear to be contrary to the findings of this report, this office should be notified so that proper modifications may be made. - - - .- .- - - - - - - - .~ - -. - -- .- - June 15, 1989 Project No: 89455 Page Eleven Prior to initiation of grading, a meeting should be arranged by the developer and should be attended by representatives of the governmental agencies, contractors, consultants and the developer. Construction should be inspected at the following stages by the Geotechnical Consultant. Upon completion of clearing and brushing. During all rough grading operations including removal of sub-standard materials, precompaction and filling operations. During trench backfilling but prior to paving or other construction over backfill. When any unusual conditions are encountered. The findings and recommendations of this report were prepared in accordance with generally accepted prefessional principles and practice in the field of Soil and Foundation engineering. This warranty is in lieu of all other warranties, either express or implied. We appreciated this opportunity to be of service on this project. If you have any questions concerning this report, please contact us at your convenience. (Standford) - - -~ - -~ - REFERENCE -- - .- - .- - - - - 1. Bonnilla, 1970 Surface Faulting and Related Effects in Earthquake Engineering, Prentice-Hall, Englewood Cliffs, Ch. 3, pp 47-74. 2. Campbell K.W., 1981, Near source attentuation of peak horizontal acceleration: Bull. seism. Sec. am., v.71, p. 2039-2070. 3. Greensfelder Roger W., 1975 Maximum Credible Rock Acceleration from Earthquakes in California: California Devision of Mines and Geology, M.S. 23. 4. Jenkins, O.P., 1967, Geologic Map of California - San Bernardino Sheet: California Division of Mines and Geology, 1:250,000. 5; Jennings, C.W. 1975, Fault Map of California, (California Geologic Data Map Series) Map No. 1, California Division of Mines and Geology. 6. Lamar, D-L., Merifield, P.M., and Proctor, R.J., 1973, Earthquake Recurrence Intervals on Major Faults in Southern California, in Geology, Seismicity and Enviromental Impact: Association of Engineering. 7. Matti, Jonathan C., and others, 1985, Distribution and Geologic Relations of Fault Systems in the Vicinity of the Central Transverse Ranges, Southern California; USGS. Open File Report a. Ploeseel and Slosson, 1974, Repeatable High Ground Accelerations from Earthquakes: CA. Geology, September. 9. Real, C.R., and other, 1978, Earthquake epicenter map of California: Calif. Div. Mines and Geology, MS 39. 10. Ziony, J.I. (Ed.), 1985, Evaluating earthquake hazards in the Los Angeles region -- An earth-science prospective: USGS. Prof. Paper 1360, 505~. 11. Ziony, and others, 1985, preliminary map showing recency of faulting in costal southern California: USGS Map MF-585. - -, .- - - - - - APPENDIX A FIELD EXPLORATION Field exploration was performed using a backhoe. The soils were continuously logged by our field personnel and classified by visual examination in accordance with the Unified Soil Classificaiton System. To evaluate the compaction characteristics of the fill material, field density tests were performed utilizing the sandcone method (A.S.T.M. D1556). Also a representative bulk sample was obtained and shipped to the laboratory in polythelene bags. - - - - - - - - .- I TRENCH LOG . Trent;! Numaa n,.uu.-r-,-.-Y~-u-r-r~-w--- .u.I....“...*.m.“I.“.“..Vu-“...-.-- .-ye-. -T-l GacLoaUUm*PC0m"e *sscmmoN UIO -mca*cn .T Metavolcanic (7) rocks- folliated, very hard, silicified, layem - ~~c&5evaz.~~” Trencn Oimensic 5 !lrh: 1 jz F 5 qBeo2 t 1 T‘ 101 A 15 -i 20 : sequence dip&into the hillslope:N-S; 50 degrees east Total Depth = 6 feet Trench Backfilled ,. Logged 3~: F.Y. Trent:! Numoe! Date: 5-89 3suiament ‘r-2 * Sandy Slope creep and colluvium-surficially disturbed bedrock, poorly sorted, gravelly material and inconsistant bedrock conditions Metavolcanic (1) rocks, folliated, very hard, silicified, layered : sequence diping into hills&ope---NlOW, 40 degrees east Total Depth 5 feet Trench Backfilled /- ‘c Mr. Lois Bikadi Fig. Nc. p(IpL No. ^^ --- TRENCH LOG iroundwarer Depth: ri Li L- c L L L Lowea BY: F.Y. &Y&A?? -9. t” 1. . ,.,,.... e..,.. 4 . . . . ..I”.. . ..I .I ,““...m.. v.uu... .* a. r*- ..4 W.C. .I ..=...c..“. .,j" cN. _,".. DC I,m ~. ,* .". ..- sm.ul <".. ". _ <"-a., e..,.. I. -I*.-.. Trench Numcer T-3 Sandy/Clayey Silts - reddish brown, loose at surface, damp, scattered pea gravels. yellowish brown med. dense to dense moist, trace o Clayey SANDS,- It. brown, scattered roothairs, moist dense (colluvium) NATIVE FILLS. TOTAL DEPTH 63FFZT TRWCHBACKFILLED I ! - L 1; L T Logged 3Y:F.y. Oate: 5-89 Eauicment: Trencz Numcer T-4 Nuriaca Eievarion: rem rem 3”: 1”s: olh: ‘tern men *wr I - 12.; 13.6 arrs SIC 3e I I i 3 t ir ndwi - ! - .11.7/- -?a r 1 Sandy/Clayey Silts - Reddish brown, loose, dry to damp, scatters coarse sands. \ Sandy Silts -'Yellotish brown, med. dense to dense, moist, tract of clays FILLS Clayey Sands - Brown, trace of roothairs, moist, dense, NATIVE FILLS TO'@L DEPTH 63FEET TIEZNCHBACXFILLED .AKESHORE MR. LOIS BEAD1 Fiq. NO. Engineering 2 FF(OJ. NO. 89-055 CONSULTIM CIVIL ElfllEEBS APPENDIX B 89-055 Bikadi LABORATORY TESTING MOISTURE DENSITY - - - - - - - - - Moisture-density information usually provides a gross indication of soil consistency and can delineate local variations at the time of investigation and provide a correlation between soils found on this site and other nearby sites. The dry unit weight and field noisture content were determined for selected samples, and the results are shown on the log of boring sheets. MAXIMUM DENSITY-OPTIMUM MOISTURE TESTS A selected soil sample was tested in the laboratory to determine maximum dry density and optimum moisture content using the A.S.T.M. D1557-78 compaction test method. This test procedure uses 25 blows Of a lo-pound hammer falling a height of 18 inches on each of five layers to a l/30 cubic foot cylinder. The results of the tests are presented below: Optimum Trench Maximum Moisture No. Depth Soil Description Dry Density Content T-2 O-3 Ft Silty ,SAND 120.0 12.5 Direct Shear Direct shear tests were made with a direct shear machine at a constant rate of strain. The machine is designed to test the SOilS without completely removing the samples form the brass rings. Samples were tested to evaluate the internal angle of frictionand cohesion. The samples to evaluate the interanl angle of friction and cohesion. The samples were tested at the increased moisture contents. The test results are shown in terms of the Coulomb shear strength parameters below. Angle of Coulomb Internal Soil Cohesion Freiction Location Description (lbs.,sq.ft.) (Degrees) Sample recovered Sandy Silt 200 25 (Peak) from trench 2 * Sample remolded to 90% Relative Cbmpaction APPENDIX C-l - -. - - - - - - .- - SUGGESTED ITEMS TO INCLUDE IN STANDARD GRADING SPECIFICATIONS These specifications present the usual and minimum requirements for grading operations performed under the observation and testing of LAKESHORE ENGINEERING, INC. No deviation from these specifications will be allowed, except where specifically superseded in the preliminary geology and soils report, or in other written communication signed by the Soils Engineer or Engineering Geologist. I GENERAL A. The Soils Engineer and Engineering Geologist are the Owner's or Builder's representative on the project. For the purpose of these specifications, observation and testing by the Soils Engineer includes that observation and testing performed by any person or persons employed by, and responsible to, the licensed Civil Engineer signing the soil report. B. All clearing, site preparation of earthwork performed on the project shall be conducted by the Contractor under the observation of the Soils Engineer. C. It is the Contractor's responsibility to prepare the ground surface to receive the fills to the satisfaction of the Soils Engineer and to place, spread, mix, water and compact the fill in accordance with the specifications of the Soils Engineer. The Contractor shall also remove all material considered unsatisfactory by the Soils Engineer. D. It is also the Contractor's responsibility to have suitable and sufficient compaction equipment on the jobsite to handle the amount of fill being placed. If necessary, excavation equipment will be shut down to permit completion of compaction. Sufficient watering apparatus will also be provided by the Contractor, with due consideration for the fill material, rate of placement and time of year. ..- - - .-~ - - Suggested Items to Include in Standard Grading Specifications E. A final report will be issuedd by the Soils Engineer and Engineering Geologist attesting to the Contractor's conformance with these specifications. II SITE PREPARATION A. B. C. D. E. All vegetation and deleterious material such as rubbish shall be disposed of offsite. This removal must be concluded prior to placing fill. The Soils Engineer shall locatee all houses, sheds, sewage disposal systems, large trees or structures on the site or on the grading plan to the best of his knowledge prior to preparing the ground surface. Soil, alluvium or rock materials determined by the Soils Engineer as being unsuitable for placement in compacted fills shall be removed and wasted from the site. Any material incorporated as a part of a compacted fill must be approved by the Soils Engineer. After the ground surface to receive fill has been cleared, it shall be scarified, disced or bladed by the Contractor until it is uniform and free from ruts, hollows, hummocks or other uneven features which may prevent uniform compaction. The scarified ground surface shall then be brought to optimum moisture, mixed as required, and compacted as specified. If the scarified zone is greater than twelve inches in depth, the excess shall be removed and placed in lifts restricted to six inches. Prior to placing fill, the ground surface to receive fill shall be inspected, tested and approved by the Soils Engineer. Any underground structures such as cesspools, cisterns, minimum shafts, tunnels, septic tanks, wells, pipe lines or others not located prior to grading are to be removed or treated in a manner prescribed by the Soils Engineer. - - L - - - - III COMPACTED FILLS A. Any material imported or excavated on the property may be utilized in the fill provided each material has been determined to be suitable by the Soils Engineer. Roots, tree branches and other matter missed during clearing shall be removed from the fill as directed by the Soils Engineer. B. Rock fragments less than six inches in diameter may be utilized in the fill, provided: 1. They are not placed in concentrated pockets. 2. There is a sufficient percentage of fine-grained material to surround the rocks. 3. The distribution of the rocks is observed by the Soils Engineer. C. Rocks greater than six inches in diameter shall be taken offsite, or placed in accordance with he recommendations of the Soils Engineer in areas designated as suitable for rock disposal. Details for rock disposal such as location, moisture control, percentage of rock placed, etc., will be referred to in the "Conclusions and Recommendations" section of the soils report. If rocks greater than six inches in diameter were not anticipated in the preliminary soils and geology report, rock disposal recommendations may not have been made in the "Conclusions and Recommendations" Section. In this case, the Contractor shall notify in diameter are encountered. The Soils Engineer will then prepare a rock disposal recommendation or request that such rocks be taken offsite. D. Material that is spongy, subject to decay, or otherwise considered unsuitable shall not be used in the compacted fill. E. Representative samples of materials to be utilized as compacted fill shall be analyzed in the laboratory by the Soils Engineer to determine their physical properties. It any material other than that previously analysis of this material shall be conducted by the Soils Engineer as soon as possible. - F. Material used in the compacting process shall be evenly spread, watered or dried, processed and compacted in thin lifts not to exceed six inches in thickness to obtain a uniformly dense layer. The fill shall be placed and compacted on a horizontal plane, unless otherwise approved by the Soils Engineer. - - - G. If the moisture content or relative compaction varies from that required by the Soils Engineer, the Contractor shall rework the fill until it is approved by the Soils Engineer. H. Each layer shall be compacted to 90 percent of the maximum density in compliance with the testing method specified by the Controlling governmental agency. (In general, ASTM D1557-70T will be used.) If compaction to a lesser percentage is authorixed by the controlling governmental agency because of a specific land use or expansive soil conditions, the area to receive fill compacted to less than 90 percent shall either be delineated on the grading plan or appropriate reference made to the area in the soil report. I. All fills shall be keyed and benched through all topsoil colluvium, alluvium or creep material, into sound bedrock or firm material where the slope receiving fill exceeds a ratio of five horizontal to one vertical, in accordance with the'recommendations of the Soils Engineer. .- - - - - ..~~ - - V GRADING CONTROL A. Inspection of the fill placement shall be provided by the Soils Engineer during the progress of grading. B. In general, density tests should be made at intervals not exceeding two feet of fill height of every 500 cubic yards of fill placed. This criteria will vary depending on soil conditions and the size of the job. In any event, an adequate number of field density tests shall be made to verify that the required compaction in being achieved. - C. Density tests should also be made on the surface material to receive fill as required by the Soils Engineer. - - - - - - - D. All cleanout, processed ground to receive fill, key excavations, subdrains and rock disposal must be inspected and approved by the Soils Engineer (and often by the governing authorities when such areas are ready for inspection. VI CONSTRUCTION CONSIDERATIONS A. Erosion control measures, when necessary, shall be provided by the Contractor during grading and prior to the completion and construction of permanent drainage controls. B. Upon completion of grading and termination of observations by the Soils Engineer, no further filling or excavating, including that necessary for footings, foundations, large tree wells, retaining walls, or other features shall be performed without the approval of the Soils Engineer or Engineering Geologist. C. Care shall be taken by the Contractor during final grading to.preserve any berms, drainage terraces, interceptor swales, or other devices of a permanent nature of or adjacent to the property. - - - -