The URL can be used to link to this page

Home My WebLink AboutMS 04-07; 952 PINE AVENUE CONDOMINIUMS; REPORT OF SOIL INVESTIGATION; 1988-02-08RECEIVED i; ry fr 1• AUG 182004 CITY OF CARLSBAD February 8, 1988,. PLANNING DEPT . TRI CITY ENGINEERS WP - 2704 A CALIFORNIA CORPORATION : Jim Weber 580-A Beech Avenue Carlsbad, California 92008 Subject: Report of Soils Investigation for property located at 952 Pine Avenue, Carlsbad, California, known as APN 204-111-14. Dear Mr. Weber: The following report has been prepared to present the results of the investigation of soil conditions for the subject property. PROJECT DESCRIPTION AND SCOPE OF WORK This investigation was undertaken at your request to determine the supporting capacities and engineering charac- teristics of the existing bearing soils and to provide infor- mation for site preparation and subsequent foundation designs for your proposed residential buildings with wood-frame and slab-on-grade construction. The subject property has 90 feet fronting on Pine Avenue and a depth of 200 feet. The ground slopes 2% to the south- west. The site contains an existing wood frame residence and detached garage and several small Avocado and fruit trees. GEOLOGY AND SEISMICITY The earth materials immediately underlying the site are poorly cemented, medium to finely grained sands. Lithologi- cally, they resemble the Pleistocene Linda Vista Formation which crops out to the south near San Diego. No recent faulting or major earthquake epicenters (greater than Richter 5.0 M) have been reported in the immediate area. Seismic risks for the site stem principally from the Elsinore Fault Zone, located approximately forty miles to the northeast, and the postulated off-shore projection of the Rose Canyon Fault (Legg and Kennedy, 1979) situated about six miles west of Oceanside. Both faults are considered active or potentially active. From empirical correlations (Housner, 1970) and the seismic history of these zones, it is considered that a 335 OLIVE AVENUE e VISTA. CALIFORNIA 92083 a (619) 758-2220 M) a'f-01 Jim Weber Page 2 February 8, 1988 wp - 2704 maximum probable earthquake of 6.0 to 6.5 should be anti c.i'- pated for planning and design purposes. SITE INVESTIGATION Three trenches were excavated on February 5, 1988 tô provide access for examination of subsurface conditions and sampling of the underlying soils for testing. Representa- tive samples of the soils encountered were -classified in the field and tested in the laboratory to determine selected engineering properties. In order to provide more direct correlation between field and laboratory testing and to aid in evaluating allow- able bearing values, in-place density tests and dynamic cone penetration tests were made at representative locations in the trenches and boring. Results of these tests and field descriptions are shown on the attached boring logs. LABORATORY TESTING The on-site soils were determined to be nonexpansive. Moisture-density curves were prepared on representative samples of the soil types encountered in accordance with ASTM D-1557-78 with the following results: n SOIL TYPE DESCRIPTION OPTIMUM MOISTURE MAXIMUM DRY DENSITY I Brown, silty, fine to medium .SAND 8.1% 128.2 PCF II Tan-orange, silty, fine to medium SAIM 8.6% 129.6 PCF 1 FINDINGS AND RECOMMENDATIONS The following summarized findings and recommendations are based on analysis of all the data and information obtain- ed from our soil investigation conducted on this site. This includes our visual inspections of the site, field investiga- tion (including the trench excavations and the boring ad- vanced throughout this site), review of published soils and geological data, and our general knowledge, and experience with the area and the encountered soil types. There were no obvious geologic hazards or unusual soil conditions detected during the investigation which would preclude the development of the site as described herein. Jim Weber Page 3 February 8, 1988 WP - 2704 It is our opinion that the site is suitable for develop- ment with respect to soil conditions, provided the recomrn•ñ- dations contained in this report are incorporated into tb project planning, design, and grading considerations. General Soil Conditions and Site Preparation The relatively uniform soil profile for the site shows approximately three feet of. loose, brown, silty SAND (SM) over a dense tan-orange silty SAND. These sands are angular and lightly cemented to the depths of.our investigation. These soils are not detrimentally expansive and, therefore, no special consideration need be given this aspect of the foundation design or construction. The loose surficial soils (to a depth of approximately three feet) having an in-situ rela- tive compaction of less than 83% are potentially subject to large rapid settlement upon wetting. These soils, therefore, require recompaction. The surface soils located under proposed structures and for a distance of nine feet beyond, in plan view, should be removed and recompacted to a relative compaction of at least 90% ASTM D-1557-78. The depth to which the recompaction operation will be taken will depend on the depth at which the dense Soil Type II is encountered. This depth is expeätd to be between 2.5 and 3.5 feet below the existing surface. Fill soils and an old septic tank were encoun- tered in the western end of Trench No. 2. Past experience in this area indicates the possibility of a vertical seepage pit being located in the general vicinity of the septic tank. Care should be taken during recompaction operations to locate, and if found, properly backfill any such pit en- countered. All grading, clearing, and recompaction opera- tions should be performed in accordance with the applicable grading specifications appended to this report and the City of Carlsbad Grading Ordinance and should be observed by a qualified soils engi- fleer at the time the work is performed. Jim Weber Page 4 February 8, 1988 WP - 2704 Foundations Conventional concentrically loaded spread footings are recommended forfoundation support. All footings should extend a minimum of 12 inches into the dense natural marine sands or properly compacted on-site marine sands. Building code standards may require greater footing depths. Continuous and square footings should have minimum widths of 12 and 24 inches, respectively. Actual footing dimensions will, of course, depend on the structural characteristics of the building program. Bearing Capacity Footings founded in the properly recompacted surf icial sands or underlying dense sands may be designed for vertical bearing pressures of 2,000 pounds per square foot. Lateral Resistance Soil passive pressure and/or coefficient of friction of concrete to soil may be used to resist horizontal movement. The allowable passive pres- sure may be assumed to be equivalent to a fluid weighing 300 pounds per cubic foot. The coeffici- ent of friction of concrete to soil may be assumed to be 0.40. These values may be increased one- third for wind or seismic loading. They have been computed assuming no surcharge and assuming adja- cent grade is level. If these assumptions are incorrect, we should be contacted for new values to reflect the true conditions. Foundation Reinforcement Foundation reinforcement should be determined by the project structural engineer. However, minimal reinforcement should consist of at least one No. 4 bar at the top and bottom of all continu- ous footings. The steel should be positioned to provide the maximum depth of reinforced concrete acting as a continuous beam. Slab-on-grade Slab thickness and reinforcement will depend upon anticipated loads. Slabs should be at least 3.5 inches thick. Where moisture migration through Jim Weber Page 5 February 8, 1988 WP - 2704 slabs is undesirable, a visqueen moisture barrier should be placed beneath them. . Drainage . . Adequate measures should be undertaken to properly finish-grade each building pad after the structural and other improvements are in place so that the drainage waters from the improved site and the adjacent properties will be directed away from the foundations, footings, and floor slabs via surface swales and/or subsurface drains toward the street or the natural drainage direction for this area. Proper drainage will ensure 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 structures and other improvements. FINAL COMMENT Because of the presence of loose surf icial soils present on. the site, grading and recornpaction work will be necessary to provide a suitable surface to receive the anticipated slab-on-grade foundations. Procedures for this have been addressed in this report. Arrangements for compaction test- ing should be made with a qualified soil testing company prior to preparation of native surfaces or placement of fill. Additional tests will be required on any imported fill and on any soils encountered during grading other than those described in this report. In order for our engineers to evaluate the finished graded site, all earthwork and compaction operations must be performed under the observation of our soils engineer so that he may have sufficient information for preparation of a report which will include his opinion regarding conformance of the completed earthwork to the recommended grading speci- fications and compaction requirements found in this report. LIMITATIONS The recommendations of this report pertain only to the site investigated and are based on the assumption that the soil conditions do not deviate from those disclosed in the borings. If any variations or undesirable conditions are encoun- tered during construction or if the proposed construction Jim Weber Page 6 February 8, 1988 WP - 2704 will differ from that planned at the present time, TRI CITY ENGINEERS should be notified so that supplemental recornme1da- tions can be given. The findings of this report are valid as of the prëént date. However, changes in the conditions of a propertycan occur with the passage of time. In addition, changes in engineering or construction standards may occur as a result-. of legislation or broadened knowledge. Accordingly, the findings of this report may be invalidated wholly or in party by changes outside our control. Therefore, this report should be reviewed after a period of one year to verify whether our recommendations remain applicable to the site. This report is issued with the understanding that it is the responsibility of the owner, or of his representative, to ensure that the information and recommendations contained herein are brought to the attention of the architect and engineer for ..the project and are incorporated into the plans and that the necessary steps are taken to see that the con- tractor and subcontractors carry out such recommendations in the field. We appreciate this opportunity to be of service to you. Respectfully, ThI ENGINEERS L Alexander W. Urquhart P. E. No. C 30958. P. E. No. GE 848 AWU/dip ends 270SOIL.RSI TYPE OF EXOIPMET: BACKHOE SURFACE ELEVATION: - - - LOGGED BY: DLP 1)ET1O GROUNDWATER:' NONE ENCOUNTERED THENCE WIDTH: TWO FEET (2') DATE: February 5, 1988 DESCRIPTION AND CLASSIFICATION ___ TION p.ataicA - WATER .RI RELATIVE (X)KPAC- COHESION PENETRO- (TORVANE) METER qu SOIL DEFIH SAMPLE RfIS- (DNTENI I)ERSITY flOW DESCRIPTION AND REMARKS SYMBOL (1SF) (1SF) TYPE (FEET) TYPE lANCE * () ;(p(7) () BROWN, MOIST, LOOSE, SILTY SAND SM I (TOPSOIL) B 2 7.7 101.7 79.4 TAN-ORANGE, DRY, LOOSE, SILTY SAND SM II - 2 B 7 5.0 100.3 77.4 3 45 4.7 106.6 82.3 TAN-ORANGE, DRY, DENSE TO VERY SM II - 4 50 3.3 121.3 93.6 DENSE SILTY SAND -5— BOTTOM OF TRENCH B=Bag Sample Number of blows required to drive a 2-inch cone 4 inches using a 35- pound hammer falling 24 inches. . . K X PLO RAT OR! LOG TRI CITY ENGINEERS JAMES WEBER 335 OLIVE AVENUE 952 PINE AVENUE, CARLSBAD, CALIFORNIA VISTA, CALIFORNIA 92083 (619) 758-2220 PROJECT NO.: WP -2704 DATE: FEBRUARY 8, 1988 ITRENCH NO.: 1 TYPE OF U]B4ENT: BACKHOE SURFACE ELEVATION: - LOGGED BY: DL? DEPTH TO OUNEMAIER: NONE ENCOUNTERED 'TRENCH WIDTH: TWO FEET (2') DATE: FEBRUARY 5,1988 DESCRIPTION AND CLASSIFICATION PA- lION WATER 1. ;)RY 'RELATIVE (X)MPAC- COHESION PENETRO J (ToRvANE) METER qu SOIL DEPTH . SAMPLE RESIS- (X)NIENT DENSITY lION DESCRIPTION AND REMARKS SYMBOL (1SF) (1SF) TYPE (FEU) TYPE IA14CE t () .. (pep) () BROWN, MOIST, LOOSE, SILTY SAND SM I S (TOPSOIL & FILL) -1 -2 2 9.1 102.8 80.2 -3 TAN-ORANGE, MOIST, LOOSE, SILTY SM II SAND (FILL?) - 4 4 8.4 102.8 79.3 5 TAN-ORANGE, MOIST, DENSE, SILTY SM II SAND 18 BOTTOM OF TRENCH S B=Bag Sample Number of blows required to drive a 2-inch cone 4 inches using a 35- pound hammer falling 24 inches. EXPLORATORY LOG TEl CITY ENGINEERS JAMES WEBER 335 OLIVE AVENUE 952 PINE AVENUE, CARLSBAD, CALIFORNIA VISTA, CALIFORNIA 92083 (619) 758-2220 PROJECT NO.: WP - 2.04 l Th: FEBRUARY 8, 1988 ]TRENCH NO.: 2 TYPE OF X?UThENT: BACKHOE SURFACEELEVATION: - LOGGED BY: DLP pj' IYJ JNwEER: NONE ENCOUNTERED THENCH WIDTH: TWO FEET (2 1 ) DATE: FEBRUARY 5, 1988 DESCRIPTION AND CLASSIFICATION I I PRA- lION WATER DRY IRJ (X)MPAC- COHESION PENETRO- (TORVANE) METER Qu SOIL rr DEPTH SAMPLE REElS- (X)NIERY DENSITY lION DESCRIPTION AND RERARKS SYMBOL (TSP) (TSP) (FEET) TYPE TANCE BROWN, MOIST, LOOSE, SILTY SAND SM I (TOPSOIL) -1 IAN-ORANGE, DRY, LOOSE, SILTY SM II - 2 SAND (NAT.) 5 4.5 101.3 78.2 -3- 45 3.0 118.5 91.4 TAN-ORANGE, DRY, DENSE TO VERY SM II DENSE,. SILTY SAND - 4 --5— BOTTOM OF TRENCH B=Bag Sample * Number of blows required to drive a 2-inch cone 4 inches using a 35- pound hammer falling 24 inches. EXPLORATORY LOG TRI CITY ENGINEERS JAMES WEBER 335 OLIVE AVENUE 952 PINE AVENUE, CARLSBAD, CALIFORNIA VISTA, CALIFORNIA 9208.3 PROJECT NO.: WP - 2704 1m: FEBRUARY 8, 1988 TRENCH NO.: 3 (619) 758-2220 VVP —27Oc 64/s T'4'C 57'c piNg ViA/UG