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HomeMy WebLinkAboutCT 71-05; Loma Laguna Unit 1 Lot 1; Soils Report; 1978-02-02WILLIAM S. KROOSKOS 6 ASSOCIATES - - ,- - - February 2, 1978 Mr. Lewis Chase Bee Cee Company 3095 state street CtlJClShdd, California 92008 Job No. 78-5581 SUEJI:CT: Report of Certification of Compacted Pill Loma Laquna Unit X0. 1 - Lot ;jo. 1 Kelly & Park Drives Carlsbad, California Dear Yr. Chase: In accordance with your request, WC have inspected the qradinq operation and tested the fill materials that were placed on the above subject Lot No. 1. This rel~)ort has been prepared to certify to the dcc~rce of compaction of the fill materials placed and compacted on the site by Cud Osuna Tractor Service between January 30, through February 1, 1978, and in conformance with the attached Grading Specifications. GlzUXP,L: ----_-. The site, consisting of Parcel :40. 1 of Lot P!o. 1 of Loma Laguna Unit !Io. 1, is being improved to receive a single family dwelling a maximum of two stories in height, to be constructed of conventional slab-on--grade and wood frame-stucco construction. The site showing the approximate location of compacted fill is delineated on the enclosed Plot Plan, Figure ??o. I. The grading operation consisted of placing and compacting on-site excavated fill soils to the finish grades as shown on the Gradiny Plan prepared by Rick Engineering Company. The maximum amount of fill was on the order of 10 feet deep. For the exact location of property lines, parcel numbers, etc., please refer to the Grading 'Plan for Lot 140. 1 of Loma Laguna Unit N . 1, Ma a 7292 (Proposed ?linor Subdivision NO. 302), Carlsbad Tr ct 71-5, approved June 13, 1977. Prior to the grading operation, the site was unimproved and in its natural state. Originally, the lot which is the subject of this report, was left as a part of a lot that had an existing dwelling located on it. Please reference our Report of Certification of Compacted Fill for Loma Laguna Subdivision dated July 27, 1972. Inspections and tests were performed on fill soils located adjacent to Lot NO. 1 on Park Drive. Page 2 Report of Certification of Compacted Fill Loma Laguna LJnit No. 1 - L,ot :Jo. 1 Kelly & Park Drives Carlsbad, California Job No. 78-5581 - - - - PREPARATION OF SITE: Prior to the placement of any fill materials, the area to receive compacted fill was cleared of all vegetation, brush, and debris. The natural ground was scarified a minimum depth of 12 inches, watered to optimum requirements, compacted and tested to 90 percent of maximum dry density. In the location of the proposed fill slope the natural ground was properly "benched" to provide a good seat and bond for the compacted fill. FILL MATERIALS AND PLACIXENT: The soils used in the fill were obtained from on-site excavations and primarily consist of brown clayey sands. These fill materials were spread in layers not exceeding eight inches in compacted thickness, watered to optimum requirements and compacted to at least 90 percent of maximum dry density by means of heavy construction equipment, including a shecpsfoot roller. FIELD DENSITY TESTS: Field density tests were taken as required, at least one test for each two feet of vertical fill depth and are indicated on Figure NO. II. The field density tests were taken in accordance with A.S.T.M. Test Method D 155G. A moisture determination was made from each in-place field test. The relative compaction results, as summarized on Figure No. II, is the ratio of t!le field density to the maximum laboratory density expressed as a percentage for the comparable material. LABORATORY TESTS: A disturbed sample of the representative fill materials was brought to the laboratory and tested. The following tests were performed on the soils in order to determine their physical and mechanical characteristics. !4echanical Analysis: A mechanical analysis was performed on the fypical soil sample in order to determine the physical and mechanical characteristics, with regards to percentage of grain size. The analysis was according to A.S.T.M. 442-54T. A Unified Soil Class- ification Triangular Chart was then utilised to classify the soils. Page 3 Report of Certification of Compacted Fill Loma Laguna Unit No. 1 - Lot Xo. 1 Kelly & Park Drives Carlsbad, California Job No. 78-5581 -. - Compaction Test: A laboratory compaction test was conducted on the typical bearing fill soils in conformance with A.S.T.M. Test Method D 1557 (four inch mold, five layers, 25 blows each layer, 10 pound hammer, 18 inch drop using all material passing a NO. 4 sieve). The maximum density represents the value to which it is possible to compact the soil in the field with the proper compactive effort. Expansion Test: An expansion test was conducted on the brown clayey sands in accordance with the requirements of the County of San Diego Test for Expansive Soils. CONCLUSIONS AND RCCOM?lENDATIO:JS: - The following summarized conclusions and recommendations are based on the analysis of all the data and information obtained from the testing of the fill materials placed on this residential site. This includes our visual inspection of the grading operation: field investigations and laboratory tests on the typical bearing soils; and our general knowledge and experience with the natural ground soils and the fill soils placed and compacted on this site. 1. The natural ground soils on this site consist of brown clayey sands. These soils were also utilised in the compacted fill and possess low to medium expansive characteristics with a swell varying from 3 to G percent as measured by the afore- mentioned by the aforementioned Test for Expansive Soils. 2. Since it is the intention of constructing the proposed structure and other improvements on the expansive natural ground soils and compacted fill soils, then it is recommended that the following work be performed. a. The continuous perimeter foundations shall extend a minimum depth of 12 inches into the firm natural ground or compacted fill ground: The continuous foundations shall be reinforced with at least two Njstcel bars; one bar shall be placed near the top of the foundation and the other bar shall be placed near the bottom. b. The concrete floor slabs of the structure and garage shall be founded on at least 2 inches thick of non-expansive soils, such as silty sands, decomposed granite, etc. It is recommended that the concrete slab in the livina area onlv be reinforced with 6x6 - lO/lO steel wire mesh. I c. Concrete slabs, such as patios and pool decking, shall be founded on at leas inches thick of non-expansive soils. d. Proposed swimming pools or other subsurface structures shall be properly designed and reinforced with steel to reflect the expansive soils that exist on this site, and in general, shall follow the recommendations of a structural engineer or soils engineer. Page 4 Report of Certification of Compacted Fill Loma Laguna Unit No. 1 - Lot No. 1 Kelly & Park Drives Carlsbad, California Job No. 78-5581 3. The natural ground soils on this site were properly prepared to receive the fill soils. The fill soils were properly placed, watered to optimum requirements, and compacted to at least 90 percent of maximum dry density. 4. Since a soil investigation of this site was conducted by our firm (Please reference our Report of Soil Investigation dated September 20, 19701, it is our opinion, that the natural ground soils and compacted fill soils possess a safe soil bearing value of 2,000 pounds per scIuare foot. This soil bearing value may be used in the design of foundations and footings of the proposed structure when founded a minimum depth of 12 inches into the natural ground and/or compacted fill. This soil bearing value may be increased one-third for design loads that include wind or seismic analysis. 5. The minimum depth of the continuous foundations and spread footings into the compacted fill ground or firm natural ground, of course, will depend on the minimum requirements of the engineering of the structure. 6. Foundations and footings of the proposed structure, walls, etc., when founded five feet and further away from the top of compacted fill slope may be of standard design in conformance with the recommended soil bearing value. If proposed foundations and footings are located closer than five feet inside the top of compacted fill slopes, they shall be deepened one foot below a 1.5 horizontal to 1.0 vertical line projected outward and down- ward from a point fi~vo feet horizontally inside the top of compacted fill slope. (Refer to Figure Xo. III) 7. The compacted fill soils that occur within five feet of the face of the fill slope possess poor lateral stability, even though they have been certified to a relative compaction of 90 percent of maximum dry d,ensity or better. Proposed structures and other improvements such as walls, fences, patios, sidewalks, swimming pool, driveways, asphalt pavement, etc., that are located within five feet of the face of compacted fill slope could suffer differential movement as a result of the poor lateral stability of these soils. 8. Planter areas and planter boxes shall be sloped to drain away from the foundations, footings, and floor slabs. Planter boxes shall be constructed with a subsyrface drain installed in gravel with direction of flow away from the foundations, footings, and floor slabs towards the outlet at the lower level of the site. 9. IJatural ground cut slopes and compacted fill slopes of maximum inclinations of 1.5 horizontal to 1.0 vertical or flatter shall be stable for the materials native to this site and utilized in the compacted fills. Page 5 Report of Certification of Compacted Fill Loma Laguna Unit No. 1 - Lot 1Jo. 1 Kelly & Park Drives Carlsbad, California Job ?do. 78-5581 10. It is recommended that all compacted fill slopes and natural cut slopes be planted with an erosion resistant plant, in conformance with the requirements of the City of Carlsbad. 11. Any backfill soils placed adjacent to swimming Poole excavations, in utility trenches, or behind retaining walls which support structures and other improvements such as patios, sidewalks, driveways, pavement, etc., (other than landscaping) shall be compacted to at least 90 percent of maximum dry density. 12. Adequate measures shall bc undertaken to properly finish grade the site after the structure and tile other improvements are in place, such that the drainage waters from the site and the adjacent higher properties are directed away from the foundations, footings, floor slabs, and tops of slopes via surface swales and subsurface drains towards the lower level of the site or to the natural drainage direction for this area. Proper surface and subsurface drainage will insure that no waters will seek the level of the bearing soils under the foundations, footings, and floor slabs which could result in undermining and differential settlement or uplift to the structure and other improvements. LIMITATIONS: The conclusions and recommendations made in this report were obtained from site inspections and tests performed by our firm in the tested area shown on Figure No. I. They are applicable only during the grading operation that we inspected and are representative of the site at the time our report was prepared. WC are not to be held responsible for subsequent changes made to the site by others which directly or indirectly causes poor surface drainage and/or water erosion. If you have any questions concerning this report, please do not hesitate to call us. This opportunity to be of service is sincerely appreciated. Respectfully submitted, KILLIAY S. KROOSKOS & ASSOCIATES WSK:skm (4) Addressee President RCE 11318 WILLIAM S. KROOSKIJS ii ASSOCIATES ,.- - - - - - - - - - - - - ,- ,- 801L AND FOUNDATION ENC3lNEERING 4320 "ANDEVER AVENUE . SAN DIE00. CALIFORNIA 92120 . PHONE 283.6506 - _ ..__~ ~~ mz- FIELD DEN SlTY TESTS JOB Loma Laguna IJnit No. 1 - Lot E:o. 1; !:elly L Park Drives; Carlsbad. CA JO8 NVMBER 78-5581 L'd" DCPTH 0, LOCATlON FlLl. IFWTI 1 See Plot Plan 2 2 (. 3 I' 4 81 .5 I' NOTE: 1: 4 II 6 I! 8 4, F.G. (10) MOISTURE DRY DENSIT” PERCENT a c LB5,IC”~ FT. t 13.0 109 12.0 111 13.6 110 9.1 113 8.0 113 F.G. denotes the field density test taken at the finish ground grade. DATE February 2, 1378 RELATIVE 501l. COMPACTION DATE TYPL (PERCENT OF TEST I 90 I 92 I 91 II 91 II 91 l-30-78 l-30-78 1-31-78 l-31-78 2-01-78 LABORATORY STANDARDS SOIL OPTIPlUy :IOISTURL: MAXIMU? DRY DENSITY TYPE CLASSIFICATION (Percent) -- (pounds/cubic ft.) 1 Brown Silty 13.4 120 Clayey Sand II Light Brown Clayey 9.0 124 p!edium to Coarse Sand PAGE 1 OF 1 Figure No. IT I I I I / I I I I I I I I I Proposed S;;re ;,, Concrete Floor Slab 11 -, 1 -. .- - -..*I -Top of Compacted . - -. L - - - Compacted Fill Slope Maximum Inclination .- - Reinforcement of - _ of the Architect or Structural- Engineer - Concrete Foundation Compacted Fill TYPICAL SECTION ( Showing Proposed Foundation Located Within Five Feet of Top of Compacted Fill Slope) Job NO. 78-5581 Figure No. III