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Home My WebLink AboutPUD 88-04H; BERMAN POOL HOUSE; PRELIMINARY GEOTECHNICAL RECOMMENDATIONS; 2005-06-14~ -(ONSTRtlCTION TESTING & ~GINEERING, INC. SAN DIEGO, CA 1441 Montiel Road Suite 115 Escondido, CA 92026 (760) 746-4955 (760) 746-9806 FAX June 14, 2005 Mr. Bill Berman 8042 Paseo Avellano Carlsbad, California 92009 Telephone: 858.350.8855 RIVERSIDE, CA 12155 Magnolia Avenue Suite 6C Riverside, CA 92503 (951) 352-6701 (951) 352-6705 FAX VENTURA,CA 1645 Pacific Avenue Suite 107 Oxnard, CA 93033 (805) 486-6475 (805) 486-9016 FAX Subject: Preliminary Geotechnical Recommendations Proposed Pool House and Swimming Pool 8042 Paseo Avellano Carlsbad, California Mr. Berman: TRACY,CA 242 W. Larch Suite F Tracy, CA 95376 (209) 839-2890 (209) 839-2895 FAX SACRAMENTO, CA 3628 Madison Avenue Suite 22 N. Highlands, CA 95660 (916) 331-6030 (916) 331-6037 FAX CTE Job No. 10-7786G Via Facsimile: 858.350.9855 ~ .... o.- C:'.) At your request, Construction Testing & Engineering, Inc. (CTE) has initiated the investigation of the referenced site. Our investigation activities have included a review of previous reports for this site area, geologic reconnaissance and the observation of existing excavations for improvement at the subject site. C,,j The Tertiary-aged Santiago Formation, which was observed underlying the site, was found to consist mainly of dense, slightly moist, light brown, fine to medium-grained silty sands. This competent native material is considered adequate for support of additional engineered fills and the proposed construction. Groundwater was not observed within the existing excavations on-site. Although groundwater conditions will likely vary, especially during periods of sustained precipitation, it is not expected to affect the proposed development provided proper site drainage is designed, constructed and maintained. Any retaining walls shall be constructed with perforated pipe, gravel, and filter fabric back drains. Our preliminary geotechnical recommendations are presented below for your use in design of this project. However, as stated, these recommendations should be-considered preliminary in nature and may require modifications based on the conditions encountered during construction. 1.0 PRELIMINARY RECOMMENDATIONS 1.1 Foundations Continuous and isolated spread footings are suitable for use at this site. We anticipate that all building footings will be founded entirely in competent native materials identified as the Santiago Formation as recommended herein. ........, _.J ___,,. 1-1- -\\etc SCIYCPOCPiccts\ IQ-7786G\l tc_Pcelim C--eo Recs doc 0 GEOTECHNICAL. ENVIRONMENTAL. CONSTRUCTION INSPECTION AND TESTING • CIVIL ENGINEERING ~D¥f ~) ~--#VJ - Preliminary Geotechnical Recommendations Proposed Pool House and Swimming Pool 8042 Paseo Avellano, Carlsbad, California June 14, 2005 Page2 CTE Job No. 10-7786G Foundation dimensions and reinforcement should be based on allowable bearing values of 2,000 pounds per square foot (psf) for footings embedded a minimum of 12 inches in competent native materials. The allowable bearing value may be increased by one third for short duration loading which includes the effects of wind or seismic forces. Minimum footing reinforcement for continuous footings should consist of four No. 4 reinforcing bars; two placed near the top and two placed near the bottom or as per the project structural engineer. The structural engineer should design isolated footing reinforcement. Based on the preliminary plans as well as the conditions observed at the site, the maximum total static settlement is expected to be on the order of 1.0 inches and the maximum differential settlement is expected to be on the order of 0.5 inches. Due to the very dense nature of underlying materials at depth, dynamic settlement is not expected to adversely effect the proposed improvements. 1.2 Foundation Setback Footings for structures should be designed such that the horizontal distance from the face of adjacent slopes to the outer edge of the footing is a minimum of 10 feet. 1.3 Lateral Load Resistance The following recommendations may be used for shallow footings on the site. Foundations placed in engineered fill materials may be designed using a coefficient of friction of 0.30 (total frictional resistance equals the coefficient of friction times the dead load). A design passive resistance value of 250 pounds per square foot per foot of depth (with a maximum value of 1250 pounds per square foot) may be used. The allowable lateral resistance can be taken as the sum of the frictional resistance and the passive resistance, provided the passive resistance does not exceed two-thirds of the total allowable resistance. 1.4 Concrete Slab-On-Grade Lightly loaded concrete slabs should be a m1mmum of 4.5 inches thick. Minimum slab reinforcement should consist of #3 reinforcing bars placed on 18-inch centers, each way, at mid- slab height. In moisture sensitive floor areas, a vapor barrier of ten-mil visqueen (with all laps sealed or taped) shall be installed. The visqueen layer may be placed upon or near mid-height of a maximum four-inch layer of consolidated aggregate base (Sand Equivalent greater than 30). Slabs subjected to heavier loads may require thicker slab sections and/or increased reinforcement. 1.5 Walls Below Grade For the design of subterranean walls where the surface of the backfill is level, it may be assumed that the soils will exert a lateral pressure equal to that developed by a fluid with a density of 3 8 pcf. The active pressure should be used for walls free to yield at the top at least 0.2 percent of the wall height. For walls restrained so that such movement is not permitted, an equivalent fluid pressure of 58 pcf should be used, based on at-rest soil conditions. The recommended equivalent \\Cte_serverlprojects\10-7786G\Ltr_prelim Geo Recs.doc - Preliminary Geotechnical Recommendations Proposed Pool House and Swimming Pool 8042 Paseo Avellano, Carlsbad, California June 14 2005 Page 3 CTE Job No. 10-7786G fluid pressures should be increased by 30 pcf for walls retaining soils inclined at 2: 1 (horizontal: vertical) or less. Walls below the water level are not anticipated for the subject site. We recommend that all walls be backfilled with soil having an expansion index of 20 or less. The backfill area should include the zone defined by a 1: 1 sloping plane, extended back from the base of the wall. Some highly clayey onsite materials may not be suitable for backfill within a 1: 1 plane extended up from the base of the wall. Retaining wall backfill should be compacted to at least 90 percent relative compaction, based on ASTM D1557-91. Backfill should not be placed until walls have achieved adequate structural strength. Heavy compaction equipment, which could cause distress to walls, should not be used. 2.0 SITE NEAR SOURCE FACTORS AND SEISMIC COEFFICIENTS In accordance with the 2001 California Building Code, Volume 2, Figure 16-2, the referenced site is located within seismic zone 4 and has a seismic zone factor of Z=0.4. The nearest active fault, the Rose Canyon Fault, is approximately 8.5 kilometers west of the site and is considered a Type B seismic source. Based on the distance from the site to the Rose Canyon Fault, near source factors ofNv=l.1 and Na=l.0 are appropriate. Based on the subsurface explorations, the site has a soil profile type of So and seismic coefficients Cv=0.70 and Ca=0.44. We appreciate the opportunity to be of service on this project. Should you have any questions or need further information please do not hesitate to contact this office. Respectfully submitted, CONSTRUCTION TESTING & ENGINEERING, INC. Dan T. Math, GE #2665 Senior Engineer ~A:!-Stephen Hnat Project Geologist \\Cte_serverlprojects\l0-7786G\Ltr_Prelim Geo Recs.doc