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HomeMy WebLinkAboutCT 04-18; OCEAN MIST CONDOMINIUMS; GEOTECHNICAL OBSERVATION AND TESTING SERVICES DURING GRADING; 2006-01-03GEOTECHNICAL OBSERVATION AND TESTING SERVICES DURING GRADING PROPOSED OCEAN MIST CONDOMINIUMS, 325-347 OAK AVENUE CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA • • • FOR • OCEAN MIST, LLC • PMB 260300 CARLSBAD VILLAGE DRIVE, SUITE 168A-' • • CARLSBAD, CALIFORNIA 92018 • W.O. 4369-13-SC JANUARY 3, 2006 • cro- Geotechnical 'Geologic Environmental 5741 Palmer Way • Carlsbad California 92008 • (760) 438-3155 • FAX (760) 931-0915 January3; 2006 W 0... 4369-B-SC Ocean Mist, LLC - PMB 260300 Carlsbad Village Drive, Suite 108A.,. Carlsbad, California 92018 Attention Mr. Michael Boveni Subject:. Geotechnical Observation and Testing Services During Grading, Proposed Ocean Mist Condcininiums, 325-347 Oak Avenue, Carlsbad, San Diego County, California Dear Mr. Bovenzi This report presents a summar. of the geotechnical testing and observation services provided by GeoSoils, Inc. (GSI) curing the rough earthwork phase of development for the proposed residence. Earthwork commenced in November, 2005, and was generally completed fdr the subject site in December, 2005. Survey of line and grade was performed by others and not performed by GSI. GSI was onsite part-time during rough grading, operations, as solely determined y the client/contractor. Based on the observations and testing performed by GSI, it is our opinion that building pad footprint and adjoining contiguous'areas are generally suitable for their newly intended use, provided our recommendations are properly implemented. Unless specifically superceded herein, the • conclusions and recommendations contained in the referenced. GSI reports in the" . Appendix remain pertinent and applicable PURPOSE OF EARTHWORK • . The purpose of grading was to prepare the site for the construction of a condominium structure with basement/garage sub-floor and two additional stories above the garage, as *ell as landscape and undergrojnd utility improvements. Typical cut and fill grading operations were performed to achieve the design pad grades C? ••. - -. -• •. ., • • •.• .1 ENGINEERING GEOLOGY The geologic conditions exposed during the process of grading were regularly observed by a representative from our firm The geologic conditions encountered during grading generally were as anticipatedand presented our previous reports (GSl, 2005 and 2004; see the Appendix). GROUNDWATER Regional groundwater was not encountered during remedial earthwork within the site and, therefore, not expected to significantly influence the performance of the development. However, based on the permeability contrasts between fill and terrace deposits, perched groundwater conditions may develop in the future due to excess irrigation, poor drainage, or damaged utilities, and should be anticipated. Should manifestations of this perched condition (i.e., seepage) develop in the future, this office could assess the condition and provide mitigative recommendations, as necessary. This potential increases in shallow fill areas, and in fill-over-cut slopes. Any below-grade walls should be water-proofed and provided with subdrainage. GEOTECHNICAL ENGINEERING Preparation of Existing Ground Prior to grading, the major surficial vegetation was stripped and hauled offsite. Within the building footprint, earth materials were removed to design grade, exposing suitable terrace deposits. In areas to receive fill materials, existing unsuitable soils (i.e., colluvium and weathered terrace deposits) were removed to suitable terrace deposits. Removal depths were on the order of about 1 foot below preconstruction grades. The resultant removal bottoms were then scarified to a depth of about 6 to 12 inches, brought to at least optimum moisture content, and compacted to a minimum relative compaction of 90 percent of the laboratory standard. Deleterious trash and other unsuitable debris encountered during grading were exported from the site. Fill Placement Fill, consisting of onsite soils, was placed in 6-to 8-inch lifts, moisture conditioned, mixed to achieve near optimum moisture conditions, and compacted using earth moving equipment to a minimum relative compaction of 90 percent of the laboratory standard (see the attached Table 1). The approximate range in fill thickness was from 3 to 4 feet. Oversize material, greater than 12 inches long in dimension, was generally not encountered, nor placed onsite. Ocean Mist, LLC W.O. 4369-B-SC 325-347 Oak Avenue, Carlsbad 0 January 3, 2006 FiIe:e:\wp9\4300\4369b.goa Page 2 GeoSosis, Inc. FIELD TESTING Field density tests were performed using nuclear (densometer) ASTM test methods D-2922 and D-3017, and the sand-cone method ASTM D-1 556. The test results taken during grading operations are presented in the attached Table 1. The approximate locations of the tests taken during grading are presented on Plate 1, which uses the grading plan by Resource Development Corporation (2004) as the base map. Field density tests were taken at periodic intervals and random locations to check the compactive effort provided by the contractor. Based upon the grading operations observed, the test results presented herein are considered representative of the compacted fill in the building pad footprint. Visual classification of the soils in the field was the basis for selecting which maximum density valueto use for a given density test. Testing was provided on a part-time basis during grading, as solely determined by the contractor/client. LABORATORY TESTING Maximum Density Testing The laboratory maximum dry density and optimum moisture content for the major soil type within this construction phase was determined according to test method ASTM D-1 557. The following table presents the results: Expansion Index (E.I.) Expansive soil conditions have been evaluated for the site. Expansion Index (E.l.) testing was performed in general accordance with Standard 18-2 of the Uniform Building Code/California Building Code ([UBC/CBC], International Conference of Building Officials [lCBO], 1997 and 2001). The test results are presented below: Ocean Mist, LLC W.O. 4369-B-SC 325-347 Oak Avenue, Carlsbad January 3, 2006 FiIe:e:\wp9\4300\4369b.goa - Page 3 GeoSotls,. Inc. I rSAMPLE'LÔCATiON I I Pad I <10 I Very Low Saturated Resistivity, pH. and Soluble Sulfates Laboratory testing, regarding the site soil's saturated resistivity, pH, and soluble sulfates, is not complete at this time. An addendum report, presenting these laboratory test results, will be provided when the data becomes available. Based upon our experience with similar sites, site soils are anticipated to be negligible with respect to sulfate exposure to concrete and are expected to be corrosive to ferrous metals when saturated. Alternative testing methods and additional comments should be obtained from a qualified corrosion engineer with regard to foundations, piping, etc. CONCLUSIONS AND RECOMMENDATIONS Unless specifically superceded by recommendations presented herein, the conclusions and recommendations contained in GSI (2005 and 2004) remain pertinent and applicable. Our review and recent laboratory testing indicates that onsite soils have a very low expansion potential (E.l. 0 to 20). Therefore, the recommendations previously provided by GSI (2005 and 2004) generally remain valid. Please note that the recommendations presented are in general accordance with the industry standard of practice, but are not intended to preclude the transmission of water or vapor through the slab or foundation. Typical mitigation of water vapor transmission may include, but not necessarily limited to: lower water/cement ratio; higher concrete compressive strength; thicker slab underlayment; waterproof coatings; etc. This should be disclosed to any homeowner. Additional recommendations regarding water or vapor transmission should be provided by the structural engineer/slab or foundation designer. All footings for the proposed structure should he founded in competent terrace deposits, which should be observed by a GSl representative. In order to provide uniform foundation support, the cut portion of a cut/fill transition area of any proposed excavation (retaining wall footings, walls, steps, etc.), should be deepened to encounter suitable bearing terrace deposits and allow for the minimum footing embedment recommended herein or previously. For a transition scenario, the structural engineer should design the footings and slabs to accommodate at least ½ inch differential-settlement between these elements, otherwise some distress should be anticipated. Ocean Mist, LLC W.O. 4369-B-SC 325-347 Oak Avenue, Carlsbad January 3, 2006 Fi1e:e:\wp9\4300\4369b.goa Page 4 GeoSoxis,. Inc. SUMMARY OF RECOMMENDATIONS REGARDING GEOTECHNICAL OBSERVATION AND TESTING We recommend that observation and/or testing be performed by GSI at each of the following construction stages: During grading/recertification. During excavation. to During placement of subdrains, toe drains, or other subdrainage devices, prior to placing fill and/or backfill. After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or.flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc.), or vapor barriers (i.e., visqueen, etc.). During retaining wall subdrain installation, prior tobackfill placement. During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. During slope construction/repair. When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. GSI should review and approve such plans, prior to construction. A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. GSI should review project sales documents to homeowners/homeowners associations for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. Ocean Mist, LLC W.O. 4369-B-SC 325-347 Oak Avenue, Carlsbad January 3, 2006 FiIe:e:\wp94306\4369b.goa GeoSoils, Inc. Page 5 PLAN REVIEW Any additional project plans (grading, precise grading, foundation, .retaining wall, 'landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report: Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative of the area; however, soil and bedrock materials vary in character between excavations and natural outcrops or conditions exposed during mass grading. Site conditions may vary due to seasonal changes or other factors. Inasmuch as our study is based upon our review and engineering analyses and laboratory data, the conclusions and recommendations are professional opinions. These opinions have been derived in accordance with current standards. of practice, and no warranty, either express or implied, is given. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others, or their inaction; or work performed when GSl is not requested to be onsite, to evaluate if our recommendations have beeh properly implemented. Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In addition, this report may be subject to review by the controlling authorities. Thus, this report brings to completion our scope of services for this portion of the project. All samples will be disposed of after 30 days, unless specifically requested by the client, in writing. Ocean Mist, LLC ' ' W.O. 4369-13-SC 325-347 Oak Avenue, Carlsbad January 3, 2006 Fi1e:e:\wp9\4300\4369b.goa GeoSoils,. inc. Page 6 The opportunity to be of service is sincerely appreciated. if you should have any questions, please do not hesitate to contact our office. ~kOFESG/o Respectfully submøALN\ V4. .110 0.1340 No. RCE 47857 Certified * Exp. ) I GeoSoils, Inc. Engineering Geologist L CIVIL ohn P. nklin OF G David W. Skelly CM. ineering eologist, 340 Civil Engineer, RCE 47857 SLE/JPF/bWS/jh Attachments: Table 1- Field Density Test Results Appendix - References Plate 1 - Density Test Location Map Distribution: (4) Addressee Ocean Mist, LLC W.O. 4369-B-SC 325-347 Oak Avenue, Carlsbad January 3, 2006 FiIe:e:\wp9\43004369b.goa GeoSoils, Inc Page 7 Table 1 FIELD DENSITY TEST RESULTS ñI1SitJ.RE NO NO OR CONTENT DENSITY COMP METHOD TYPE DEPTH (ft) (%) (pcf) (%) 1 11/9/05 Unit 5 Ocean Mist -2.0 10.5 118.2 92.7 ND A 2 11/9/05 Unit 4 Ocean Mist -2.0 12.1 116.8 91.6 ND A 11/10/05 Lot Ocean Mist -1.0 11.8 116.3 91.2 SC A 4 11/10/05 Lot 1 Ocean Mist '-1.0 10.8 119.2 93.4 ND A 5 11/10/05 Lot 4 Ocean Mist FG 11.4 117.6 92.2 ND A 6 11/10/05 Lot 5 Ocean Mist -1.0 12.6 115.9 90.9 ND A 7 11/10/05 Lot Ocean Mist -1.0 11.2 118.4 1 92.8 ND I A LEGEND: FG = Finish Grade ND = Nuclear Densometer SC = Sand Cone Ocean Mist, LLC W.O. 4369-B-SC 325-347 Oak Avenue, Carlsbad January 2006 File: c:\excel\tables\4300\4369b.goa Page 1 GeoSoils, Inc. APPENDIX REFERENCES California, State of, 2001, Senate Bill 800, Burton. Liability: construction defects, February 23; approved by GovernOr September 20, 2002; filed with Secretary September 20, 2002; effective January 1, 2003. Donald, Brian, 2005, Grading plans for Ocean Mist Condominiums, 335 Oak Avenue, Project No. CT 04-18, September 13. Dunn Savoie, Inc., 2005, Foundation plan, Ocean Mist Condominiums, Sheets S-3, S-7, and S-1 0, Job No. 04322, March. GeoSoils, Inc., 2005, Update of preliminary geotechnical evaluation and plan review, proposed Ocean Mist Condominiums, 325-347 Oak Avenue, Carlsbad, San Diego County, California, W.O. 4369-Al -SC, dated October 31. 2004, Preliminary geotechniáal evaluation, proposed Ocean Mist Condominiums, 325-247 Oak Avenue, city of Carlsbad, San Diego County, California, W.O. 4369-A-SC,, dated June 21. . International Conference of Building Officials, 2001, California building code, California code of regulations title 24, part 2, volume 1 and 2. 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. ' Resource Development Corporation, 2004, Conceptual grading and drainage plan, Job Number JN01 -021 K, October 13. GeoSoils,. Inc.