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Home My WebLink AboutTract Map 32170 Corrosion Evaluation Soils~ ~ PETR~ OFFICES W THE COUNTIES OF ORANGE • SAN DIEGO • RNERSIDE • LOS ANGELES • SAN BERNARDINO Mr. Rick Rush WILLIAM LYON HOMES, INC. 11800 Sterling Avenue, Suite A Riverside, California 92503 ~2 3Zt'l0 August 22, 2005 J.N. 415-03 Subject: Corrosion Evaluation of Soils, Tract 32170, Neighborhood 6, Pads 1 through 14 (Harveston Phase II), City of Temecula, Riverside County, California References: 1) Petra Geotechnical, Inc., 2004, Post-Tensioned Foundation Design Parameters, Neighborhoods N-6 and N-12 witlvn Tract 29639-2, Harveston, City of Temecula, Riverside County, California, J.N. 287-04, dated July 21. 2) Petra Geotechnical, Inc., 2005, Geotechnical Report of Rough Grading, Tract 32170 Neighborhood 6(N-6), Pads 1 through 14 (Harveston Phase II), City of Temecula, Riverside county, California, J.N. 287-04, dated February 16. Dear Mr. Rush: Pursuant to your request, Petra Geotechnical, Inc. (Petra) has prepazed this report evaluating the corrosion potential of onsite soils within Pads 1 through 14 of Neighborhood 6 within Tract 32170 (Harveston-Phase II), located in the City of Temecula, California. In prepazation of this report, we obtained representative samples of onsite soils from Pads 1 through 14 and performed laboratory testing to determine soil chemical properties and resistivity, as well as geotechnical review of the laboratory test results to evaluate the conosion potential of the onsite soils regazding their effect on concrete and buried metallic objects. 1 PETRA GEOTECHNICAL, INC. 41640 Corning Place • Suite 107 . Murrieta • CA 92562 . Tel: (909) 600-9271 . Fax: (909) 600-9215 ~ WILLIAM LYON HOMES, INC. TR 32170 Pads 1-14/Temecula LABORATORY TESTING August 22, 2005 J.N. 415-03 Page 2 A total of I1 samples of onsite soils were obtained from the subject pads for determination of pH, minimum electrical resistivity, chloride content and soluble sulfate content. The laboratory test results aze presented in the attached Table I. CONCLUSIONS AND RECOMMENDATIONS Under current accepted standazds of practice, the determined chemical values for soluble sulfates for the subject project site indicate that the native soil will not be aggressive to concrete. In accordance with 2001 California Buiiding Code (CBC) Table 19-A-4, the soluble sulfate exposure will be negligible. Therefore, we recommend that Type II cement be used. The potential for concrete exposure to chlorides is considered to be negligible based upon the recognized State of California Department of Transportation (Caltrans), reference Standard Bridge Design Specifications. Under Subsection 8.22.1 of that document, Caltrans has determined that corrosive water or soil contains more than 500 parts per million of chlorides. Resistivity measurements and pH values indicate that the native soil will be corrosive to buried metallic structures. Metallic structures in contact with these soils should be wrapped and coated. If building slabs aze to be post-tensioned, the post-tensioning cables should be encased and/or encapsulated in accordance with the Post-Tensioning Institute Guide Specifications. Post-tensioning cable, end-plate anchors and nuts also need to be protected if exposed. If the anchor plates and nuts aze in a recess in the edge of the concrete slab, the recess should be filled in with a non-shrink, non-porous, ~ .Z U ~ WILLIAM LYON HOMES, INC. TR 32170 Pads 1-14lTemecula August 22, 2005 J.N. 415-03 Page 3 moisture-sensitive epoxy grout so that the plate and nut aze completely encased and isolated from the soil. Do not use common cement grout A standazd non-shrink, non metallic cementitious grout may be used only when the post-tension assembly is polyethylene-encapsulated similar to that offered by Hayes Industries, LTD or O'Strand, Inc. The recognized standazd of soils corrosivity classification based on resistivity is as follows. * National Association of Corrosion Engineers, Cortosion Basics in M Introduction, 1987, Page 191. The reported soils resistivity measurements aze recognized as being moderately corrosive to buried metallic objects, such as steel, iron and copper. A pH value below 9.7 is recognized as being corrosive to most common metallic construction components, including copper, iron and aluminum. Metallic stxuctures, such as piping and conduit, in contact with these soils should be wrapped with a minimum of 16 mil of dielectric (nonconductive) tape or encased in a continuous holiday free (no open joints or seams; no holes or tears) polyethylene film sleeve or heat-shrink sleeve. It is critical to the life of the pipe that the sleeve or tape contain no openings or holes. Penetrations of any kind within these or other protective materials generally leads to accelerated corrosion failure due to the fact that the ~ 3 ~ ~ • WILLIAM LYON HOMES, INC. August 22, 2005 TR 32170 Pads 1-14/Temecula J.N. 415-03 Page 4 corrosion attack is concentrated at the location of these penetrations. It is absolutely imperative that any copper water piping or other metal conduit penetrating the concrete slab or footing not come in contact with the reinforcing steel or post-tensioning tendons. However, since construction practices tend to be less than desired, it is inevitable that the protective coverings may be damaged or improperly installed. Therefore, it is recommended that plastic-piping materials be used for buried service in lieu of cast or ductile iron-waste piping or copper water piping, especially beneath the concrete slabs of the proposed structures. The recommendations outlined herein are in conformance with current accepted standazds of practice that meet or exceed the provisions of the 2001 CBC, the American Concrete Institute, National Association of Corrosion Engineers, Post- Tensioning Institute Guide specifications and Caltrans Standard Specifications. ~~ U ~ ~ WILLIAM LYON HOMES, INC. August 22, 2005 TR 32170 Pads 1-14/Temecula J.N. 415-03 Page 5 This opportunity to be of service is sincerely appreciated. If you have questions please contact the office. Respectfully submitted, PETRA Gr yson R. Walker, GE Principal Engineer GRW/ms OF Attachxnent: Table I- Laboratory Test Results Distribution: (1) Addressee (4) William Lyon homes, Inc. Attention: Mr. Fred Lutka (2) City of Temecula - Department of Public Works Attention: Mr. Reza James ~ ~ R. ~ No.871 'm w y s ,* EXP. '~ '~~ ° *~ ~ TABLEI Laboratorv Test Results ^ ~ Chloride Resistivity Carrosivity Pad Sulfate (°lo) (ppm) ', PH (o6m-eni) Potentia~, = concrete: negligible 1 0.004 140 7.8 1,000 metal: high concrete: negligible 2 0.004 140 7.7 1,700 metal: moderate concrete: negligible 3 0.004 140 7.6 3,000 metal: mild concre[e: negligible 4 0.008 150 7.5 3,100 metal: mild concrete: negligible 5 0.004 130 7.4 4,800 metal: mild concrete: negligible 6 0.008 230 7.7 1,200 metal: moderate Concrete: negligible 7 0.004 160 7.6 1,900 metal: moderate Concrete: negligible 8 0.004 130 73 1,900 metal: moderate concrete: negligible 9 0.004 130 79 2,600 metal: mild concrete: negligible 12 0.004 130 7A 1,300 metal: moderate concrete: negligible 14 0.008 140 7.9 1,600 metal: moderate PETRA GEOTECHN/CAL, INC. AUGUST 2005 (p J. N. 415-03