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HomeMy WebLinkAboutCT 10-01; Sea Breeze Villas; Geotechnical Engineering Investigation; 2010-04-20STRATA B E a c a N s - T E C H , I N C U L T A N T S 7372 Walnut Avenue, Unit F.Buena Park. Califomla 90620 April 20,2010 RECORD COPY Initial Date 714-521-5611 562-427-«)99 FAX 714-521-2552 W.0.262310 Tony Sfredo 21 Woodcrest Irvine, California, 92603 Subject: Geotechnical Engineering Investigation of Proposed Multi Family Residential Development, 391 Tamarack Avenue, Carlsba4 California. Gentlemen: Pursuant to your request, a geotechnical investigation has been performed at the subject site. The purposes of the investigaticm were to determine the general engineering characteristics ofthe soils on and underlying the site and to provide recommendations for tiie design of foundations, pavements and underground improvements. PROPOSED DEVELOPMENT It is our understanding that tiie proposed develcq)ment will consist of ^proximately 12 attached town homes of wood-framed construction with parking and landscaping. PURPOSE AND SCOPE OF SERVICES The scope of the study was to obtain subsurface information within the fm)ject site area and to provide recommendations pertaining to the proposed development and included the following: 1. A cursory reconnaissance of the site and surrounding areas. 2. Excavation of exploratory geotechnical test pits to determine the subsurface soil and groundwater conditions. 3. Collection of representative bulk and/or undisturbed soil samples for laboratory analysis. 4. LaboratCMy analyses of soil samples including determination of in-situ and maximum density, in-situ and optimum moisture content shear strength and consolidation charact^stics, expansion potential and liquefaction analysis. 5. Preparation of this report presenting results of our investigation and recommendations for the proposed development CQ ZD or >- STRATA-TECH, INC. BEOCONSULTANTS Tony Sfredo 2 W.0.262310 Geotechnical Engineering Investigation March 15.2010 SITE CONDITIONS The 117 by 266 foot rectangular lot is located on the south side of Tamarack Avenue, adjacent to the west side of the coastiine railroad tracks in Carlsbad, California. A small single story house is currently in the front of the lot, witii a debris-covered lot in the rear. The site is shown on the attached vicinity M^, Plate No. 1. Site configuration is further illustrated on the Site Plan, Plate 2. FIELD INVESTIGATION The field mvestigation was performed on February 26,2010, consisting of excavating four backhoe test pits and two hand dug percolation test holes. The locations are shown on the attached Site Plan, Plate 2. As the excavation progressed, personnel fix)m this office visually classified the soils encountered, and secured representative samples for laboratory testing. Description of the soils encoimtered are presented on the attached Test Pit Logs. The data presented on these logs is a simplification of actual subsur&ce conditions encountered and applies only at tiie specific boring locaticm and the date excavated. It is not wananted to be representative of subsurfece conditions at other locations and times. EARTH MATERIALS Earth materials raicountered withm the e}q)loratory test pits were visually logged by a representative from STRATA-TECH, Inc. The materials were classified as artificial fill and native soils. Native soils consisted of a silty residual sandy soil to a maximimi depth explored of 7 feet Groundwater was not encounters! in any of our geotechnical pits. SEISMICITY Southem California is located in an active seismic region. Moderate to sti"ong earthquakes can occur on numeiY)us &ults. The United States Geological Survey, California Division of Mines and Geology, private consultants, and universities have been studying earthquakes in Southem California for several decades. The purpose ofthe code seismic design parameters is to prevent collapse during strong ground shaking. Cosmetic damage should be expected. The principal seismic hazard to tiie subject property and proposed project is strong ground shaking fi^m earthquakes produced by local faults. Secondary effects such as surface rupture, lurching, or flooding are not considered probable. STRATA-TECH, INC. BEaCONSULTANTS Tony Sfredo 3 W.0.262310 Geotechnical Engineering Investiftation March 15.2010 20061.B.C. SEISMIC DESIGN VALUES 2003 NEHRP Seismic Design Provisions Site Class E - Fa = 1.0 ,Fv = 1.0 Spectral Response Accelerations Ss and SI = Mapped Spectral Acceleration Values Data are based on a 0.01 deg grid spacing Ss= 133 Si=0.5 Sa=.88 CONCLUSIONS AND RECOMMENDATIONS Development ofthe site as proposed is considered feasible from a soils engineering standpoint, provided that the recommenciations stated herein are incorporated in the design and are implemented in the field. Recommendations are subject to change based on review of final foundation and grading plans. It is recommended that the proposed stmctures be entirely supported by compacted fill. A minimum 1-foot thick compacted fill blanket below the bottom of the footings is recommended. For other minor stmctures such as property line walls or retauiing walls less than 4 feet high, competent native soils or compacted fill may be used for stmctural support. PROPOSED GRADING Grading plans were not available at the time our work was performed. It is assumed that proposed grades will not differ significantly from existing grades. The foUowmg recommendations are subject to change based on review of final grading plans. GRADING RECOMMENDATIONS Removal and recompaction of existing fill and loose native soils will be required to provide adequate support for foundations and slabs on grade. The depth of removal shall be 1 foot below the bottom ofthe footings. The depth of removal is estimated to be at least 3 feet. Earthwork for foundation support shall uiclude the entire building pad and shall extend a minimum of 5 feet outside exterior footing lines where feasible or to property line. While no stmctures are on adjacent properties care shall be exercised not to undermine adjacent hardscape, walls, or pavements. STRATA-TEC H,l N C BEOCONSULTANTS Tony Sfredo Geotechnical Engineering InvestigatiMi W.0.262310 March 15.2010 The exposed excavation bottom shall be observed and approved by STRATA-TECH, Inc. and the City's grading inspector prior to processing. Dependent on field observations, removals may be adjusted up or down. Subsequent to approval of the excavation bottom, the area shall be scarified 6 inches, moisture conditioned as needed, and compacted to a mmimum of 90 percent relative compaction. Fill soils shall be placed in 6 to 8 inch loose lifts, moisture conditioned as needed, and compacted to a minimum of 90 percent relative compaction. This process shall be utilized to finish grade. Grading for hardscape areas shall consist of removal and recompaction of soft surficial soils. Removal depths are estimated at 1 to 2 feet Earthwork shaU be performed in accordance with previously specified methods. Grading and/or foundation plans shall be reviewed by the soil engineer. All recommendations are subject to modification upon review of such plans. FOUNDATIONS ON COMPACTED FILL The proposed building may be supported by continuous spread and isolated footings placed a minimum depth of 24 inches below lowest adjacent grade utilizing an allowable bearing value of 2,000 pounds per square foot. This value is for dead plus live load and may be increased 1/3 for total including seismic and wind loads where allowed by code. Type Minimum Deptfi (inches) Mlnimiun Width (inches) Bearing Value (psf) Increase Maximum (psf) Type Minimum Deptfi (inches) Mlnimiun Width (inches) Bearing Value (psf) Widtii Depth Maximum (psf) Type Minimum Deptfi (inches) Mlnimiun Width (inches) Bearing Value (psf) (psfi'ft) (psfi'ft) Maximum (psf) Continuous 24 12 2000 180 440 3500 Interior Pad 18 24 2000 180 440 3500 It is recommended that aU footings be reinforced with a minimum of two no. 4 bars (1 top and 1 bottom). The stmctural engineer's reinforcing requirements should be followed if more stringent. Footing excavations shall be observed by a representative of STRATA-TECH, Inc. prior to placement of steel or concrete to verify competent soil conditions. If unacceptable soil conditions are exposed mitigation will be recommended. FOUNDATIONS ON COMPETENT NATIVE SOILS - for Minor Stmctures Minor stmctures may be supported by continuous spread footings placed a minimum depth of 24 inches below lowest adjacent grade and 12-inches into natural soil utilizing an allowable STRATA-TECH, INC BEOCONSULTANTS Tony Sfredo Geotechnical Engineering Investigation W. 0.262310 March 15.2010 bearing value of 1,500 poimds per square foot. This value is for dead plus live load and may be increased 1/3 for total including seismic and wind loads where allowed by code. Footing excavations shall be observed by a representative of STRATA-TECH, Inc. prior to placement of steel or concrete to verify competent soil conditions. If unacceptable soil conditions are exposed, mhigation will be recommended. LATERAL DESIGN Lateral restraint at flie base of footings and on slabs may be assumed to be tiie product ofthe dead load and a coefficient of fiiction of .30. Passive pressure on tiie face of footings may also be used to resist lateral forces. A passive pressure of zero at the surface of finished grade, increasing at the rate of 300 pounds per square foot of deptii to a maximum value of 2,500 pounds per square foot, may be usol for compacted fill or native soils at this site. If passive pressure and fiiction are combined when evaluating the lateral resistance, the value of the passive pressure should be limited to 2/3 ofthe values given above. RETAINING WALLS Unrestrained walls up to 5-feet in height retaining drained earth may be designed for the following: Surface Slope of Retained Material Horizontal to Vertical Equivalait Fluid Pressure Pounds Per Cubic Foot Level 30 5tol 32 4tol 35 3tol 38 2tol 43 These values include seismic loading. BackfiU should consist of clean sand and gravel. While all backfills should be compacted to the required degree, extra care should be taken wcwking close to walls to prevent excessive pressure. Retaining walls should include subdrains consistmg of 4-inch, SCH 40 or SDR 35 perforated pipe surrounded by 1 cubic foot per lineal foot of crushed rock. AU waU backfiU should be compacted to a minimum of 90 percent relative compaction. All retammg stmctures should include appropriate allowances for aiticipatod surcharge loading, where applicable. In tiiis regard, a uniformly distributed horizontal load equal to one-half the vertical surcharge shall be applied when the surcharge is within a horizontal distance equal to tiie waU height Retaining wall footing excavations shall be founded entirely in competent native soils or compacted fill. Footing bottoms shall be observed by a representative of STRATA-TECH, Inc., to verify competent conditions. STRATA-TEC H,l N C. BEOCONSULTANTS Tony Sfi«do g W. 0.262310 Geotechnical Enginecrin)z Investigation March 15,2010 EXPANSIVE SOILS Results of expansion tests indicate that the near surface soils have a low expansion potential. SETTLEMENT The maximum total post-constmcticm settl^ent is anticipated to be on tiie order of 1/2 inch. Differential settlements are expected to be less than 1/2 inch, measured between adjacent stmctural elements. SUBSIDENCE & SHRINKAGE Subsidence over tiie site during grading is anticipated to be on flie order of .5 feet Shrinkage of reworked materials should be in the range of 10 to 15 percent FLOOR SLABS TTie surfece soils are non-plastic with low expansion potential. Where concrete slabs on grade are utilized, the slab shall be supported on at least 1 foot of engineered fiU compacted to a minimum of 90 percrait relative compaction. Slabs should be at least 4 inches thick and reinforced with a minimum of no. 3 bars 24 inches on center both ways. The soU should be kept moist prior to casting the slab. However, if the soils at grade become disturbed during constiuction, they should be brought to approximately optimum moisture content and rolled to a firm, unyielding condition prior to placing concrete. In areas where a moisture sensitive floor covering will be used, a vapor barrier consisting of a plastic film (6 ml polyvinyl chloride or equivalent) should be used. The vapor barrier should be properly lapped and sealed. Since the vapor barrier wiU prevent moisture fiwm draining from fresh concrete, a better concrete finish can usually be obtained if at least 2 inches of wet sand is spread over the vapor barrier prior to placement of concrete. UnUTY LINE BACKFILLS AU utility line backfills, both interior and exterior, shall be compacted to a minimum of 90 percent relative compaction and shall require testing at a maximum of 2-foot vertical intervals. STRATA-TECH, INC. BEOCONSULTANTS Tony Sfredo 7 W. 0.262310 Geotechnical Engineering Investigation March 15.2010 HARDSCAPE AND SLABS Hardsce^ and slab subgrade areas shall exhibit a minimum of 90 percent relative ccwnpaction to a depth of at least 1 foot. Deeper removal and recompaction may be required if unacceptable conditions are encountered. These areas require testing just prior to placing concrete. STORMWATER INFILTRATION TEST RESULTS Two 3 foot deep Hand Dug test pits were excavated in the central driveway portion ofthe site on April 20,2010. The diameter of the test hole was 6-inches. The lower dq>tii ofthe pit exposed a natural soil layer of loose medium grained brown Silty SAND that is typical of the underlying soUs. The bottom of the test pit was saturated and tested the foUowmg morning. The percolation test was performed by siphoning a 5-gallon water bottle into the band-dug hole. The water level was kept at 5 to 6 inches in depth for a period of four hours. At the end of four hours, the time for the water to drop fi^om the 6* to the 5* inch was measured. ITiis value was 15 minutes for botii holes. This corresponds to a percolation rate of 15 gallcms per square foot of sidewall soil per day. The percolation rate can be expected to perform at the tested rate over a short period of time with clean water flowing into undisturbed soil. A high factor of safety should be used for longer-term use with unfiltered water. The percolation rate can be expected to increase at a power of 1.5 with respect to head increase. DRAINAGE Positive drainage should be planned for the site. Minimum drainage should be 2 percent for landscape areas and 1 percent for hardscape. Drainage should be directed away from stmctures via non-erodible conduits to suitable disposal areas. The structure shouW utilize roof gutters and down spouts tied directiy to yard drainage. Unlmed flowerbeds, planters, and lawns should not be constmcted against the perimeter of the stmcture. If such l^dscaping (against the perimeter of a stmcture) is planned, it should be properly drained and lined or provided with an underground moisture barrier. Irrigation should be kept to a minimum. This report is issued witii tiie understanding tiiat it is tiie responsibility of the owner, or of his representative, to ensure tiiat the information and recommendations contained herein are called to the attention ofthe engineers for tiie project and incorporated into the plans and that tiie necessary steps are taken to see that the Contractors and Subcontractors carry out such recommendations in tiie field. STRATA-TECH, INC. BEOCONSULTANTS Tony Sfredo g W.0.262310 Geotechnical Engineering Investigation _—— March 15,201p ENGINEERING CONSULTATION, TESTING & OBSERVATION We wiU be pleased to provide additional input with respect to foundation design once methods of constmction and/or nature of imported soil has been determined. Grading and foundation plans should be reviewed by tiiis office prior to commencement of grading so tiiat ^propriate recommendations, if needed, can be made. Areas to receive fill should be inspected when unsuitable materials have been removed and prior to placement of fiU, and fill should be observed and tested for compaction as it is placed. AGENCY REVIEW AU soU, geologic and stmchiral aspects of tiie proposed development are subject to the review and approval ofthe govemmg agency(s). It diould be recognized that the governing ^aicy (s) can dictate the manner in which tiie project proceeds. They could approve or deny any aspect of tiie proposed improvements and/or could dictate which foundation and grading options are acceptable. Su{^lemental geotechnical consulting in response to agency requests for edditional information could be required and wUl be charged on a time and materials basis. LBVnTATIONS This report presents recommendations pertaining to tiie subject site based on tiie assumption that tiie subsurface conditions do not deviate appreciably from those disclosed by our exploratory excavations. Our recommendations are based on the technical information, our understanding of tiie proposed constmction, and our experience in tiie geotechnical field. We do not guarantee the performance of tiie project, only that our enguieering work and judgments meet tiie standard of care of our profession at this time. In view ofthe general conditions in the area, the possibility of different local soil conditions may exist. Any deviation or unexpected condition observed during constmction should be brought to tiie attention ofthe Geotechnical Engineer. In tiiis way, any supplemental recommendaticms can be made with a minimum of delay necessaiy to the project If the proposed constmction wiU differ from our present understanding of the project, tiie existing information and possibfy new factors may have to be evaluated. Any design changes and the finished plans should be reviewed by tiie Geotechnical Consultant Of particular importance would be extending development to new areas, changes in sfructural loading conditions, pos^ned develc^ment for more than a year, or changes in ownership. STRATA B E O C O N S T E C H , I N C U L T A N T S Tony SScedo Geotechnical Engineering Investigation W. 0.262310 March 15.2010 This report is issued with tiie understanding tiiat it is the responsibUity of the owner, or of his representative, to ensure that the information and recommendations containol herem are called to the attention ofthe Architects and Engineers for tiie project and incorporated into the plans and that the necessary steps are taken to see that the contractors and subcontractors carry out such recommendations in tiie field. This report is subject to review by the controlling autiiorities for tiiis project We appreciate this opportunity to be of service to you. Respectfully submitted: STRATA-TECH, Inc. Roland Acufla, PG Principal Larry Finlcy RCE 46606 Enclosures: Plate 1: Vicinity Map Plate 2: Site Plan and Boring Location Map Test Pit Logs Appendfat A: Laboratory Results and Engineering Calculations Appendbc B: Specifications for Grading TRENCH LDCATinN PLAN 391 TAMARACK AVENUE. CARLSBAD. CA VtffilLJS Site Plan 10.7 12-unit Townhome Ave, Carlsbad, CA Zcm«: KM ainfitf AllowM: ^9 ur (13-unrti) [>«n»lt^ Pro(«t»d: 17.1 unlt»/«fi2i'i «f/unH (1!-untti) (min) Tutd ATM: 18.444 M.ft. ' 30,74t »q.fl. (.7 oortfi) PrttotB Potfo frm R«»ilrad: Prints PaUo ITN i^^nunf Lot Covarog* LtlhnClirag* scoie: 1" = 20'-0" Project: 391 Tamarack 60 •f/imll 3\7 WH. • 4,480 tq-ft. Plan 2 (3-6«l rm) 5,SCe KVft. Pton 3 (3-b«d rm): &^«*?3i^'b»d rni) X9S0 •q.ft. -unit* •1.S7S iq.ft, - -unit! •1,42& •q.ri. - -unlU 01,475 -•poeai/untt TEST PIT LOCATION PERCOLATION TEST PIT LOCATION STRATA-TECH, inc, 7372 WALNUT AVENUE #F BUENA PARK, CA 90620 714-521-56U 3-10 PLATE a RECORD OF SUBSURFACE EXPLORATION w m ^^ 'c Date 2/25/2010 Geotechnical Engineering Investigation Ji Q. E a ilsture ary \ a> 73 t 391 Tamarack Avenue CO Q Carlsbad, California U B Work Order 262310 Test Pit No. 1 Description of Eartti Materials 6 114 0 — 2 — 4 6 — 8 — 0- 2", TOPSOIL, MOIST, SMALL ROOTS 2- 6',: ORANGE-BROWN F-MED GR. SAND DRY 6-8', SOIL, M-F GR. SILTY SAND , DAMP DENSE End of Test Pit at 8* Feet. No Ground Water. No Caving. RECORD OF SUBSURFACE EXPLORATION m Moisture % (% dry wt.) a-Date 212512010 Geotechnical Engineering Investigation ample Moisture % (% dry wt.) Dry Desf (pcf) ipth (F 391 Tamarack Avenue OT Moisture % (% dry wt.) Dry Desf (pcf) 0 Carisbad, California U B Wbric Order 262310 Test Pit No. 2 Description of Earth Materials 0 — 1 — 2 ] 3 — 4 SURFACE: WEED COVERED YARD 0-6" TOPSOIL, BROWN SILTY SAND WITH SMALL ROOTS 6-24": LIGHT BROWN NATURAL SOIL F-MED GR SAND FAIRLY DENSE WITH SOME CLAY BINDER: MOIST 24-36" NATURAL SOIL.BROWN SILTY SAND WITH SHARP GRAVELS, COHESIONLESS End of Test Pit at 3 Feet. No Ground Water. No Caving. STRATA - TECH, INC. RECORD OF SUBSURFACE EXPLORATION "cL c u. Date 2/25/2010 Geotechnical Engineering Investigation E to Moisti (%dn Q a. 391 Tamarack Avenue tn Moisti (%dn Q. o Carisbad, California U B o Woric Order 262310 Test Pit No. 3 Description of Earth Materials -6.1 114.1 0 2 6 0-1.5- TOPSOIL. MOIST DARK BROWN SILTY SAND WITH SMALL ROOTS 1.5-'4': RESIDUAL (NATURAL) SOIL BROWN F-MED GR. SAND MOIST 4-7 yellow, M-F GR. SILTY SAND damp 5.8 1 113.7 1 8 10 12 End of Test Pit at 9-Feet No Ground Water. No Caving. RECORD OF SUBSURFACE EXPLORATION Moisture % (% dry wt.) Date 2/25/2010 Geotechnical Engineering Investigation oi a. E Moisture % (% dry wt.) Dry Desi (pcf) LL. 391 Tamarack Avenue OT Moisture % (% dry wt.) Dry Desi (pcf) Carisbad, Califomla U B Worit Order 262310 Test Pit No. 4 Description of Earth Materials 0 — 1 — SURFACE: WEED COVERED LOT 0-6" TOPSOIL, MOIST DARK BROWN SILTY SAND 6-24": BROWN NATURAL SOIL F-MED GR SILTY SAND AIRLY DENSE MOIST 2 1 3 2-3': RESIDUAL (NATURAL) SOIL BROWN F-MED GR. SAND DENSE, MOIST 4 End of Test PK at 3Feet. No Ground Water. No Caving. STRATA - TECH, INC. NEAR SOURCE FAULT MAP Geotechnical Engineering Investigation 391 Tamarack Avenue Carlsbad, California Woric Order 262310 Geotechnical Engineering Investigation 391 Tamarack Avenue Carlsbad, California Plate No. 4 STRATA - TECH, INC. STRATA-TECH, INC BEOCONSULTANTS APPENDIX A This ^)pendbc conteuns a description of the field investigation, laboratory testing procedures and results, site plan, and exploratory logs. FIELD INVESTIGATION The field investigation was performed on February 26, 2010, consistmg of the excavation of four exploratory hunches at locations shown on tiie attached Site Plan, Plate 2. As excavation progressed, persoimel fi"om this office visually classified the soils encountered, and secured representative samples for laboratory testing. Sample Retrieval- Backhoe Undisturbed samples of earth materials were obtained at fi-equent intervals by driving a thin- walled steel sampler by the hydraulic action ofthe backhoe bucket. The material was retamed in brass rings of 2.41 inches inside diameter and 1.00 inch height. The central portion of the sample was in close-fitting, watertight containers for transportation to the laboratory. Descriptions of the soils encountered are presented on the attached boring Logs. The data presented on these logs is a simplification of actual subsurfece conditions encountered and applies only at the specific boring location and the date excavated. It is not warranted to be representative of subsurface conditions at other locations and tunes. Laboratory Testing Field samples were examined in the laboratory and a testing program was then established to develop data for preliminary evaluation of geotechnical conditions. Moisture Density Field moisture content and dry density were determined for each of the undisturbed soil samples. The dry density was determined in pounds per cubic foot. The moisture content was determined as a percentage of the dry soil weight. The results of the tests are shown ui the test results section of this appendix. Compaction Character Compaction tests were performed cm bulk sample of the existing soil in accordance witii ASTM D1557-07. The results of the tests are shown in tiie test results section of tiiis appendbc. Shear Strength The ultimate shear strengths of the soil, remolded soil, highly weathered bedrock and bedrock was determined by perfcmning direct shear tests. The tests were performed in a strain-controlled STRATA-TECH, INC BEOCONSULTANTS machine manufactured by GeoMatic. The rate of deformation was 0.005 inches per minute. Samples were beared under varying confining pressure, as shown on the "Shear Test Diagrams". The samples indicated as saturated were artificially saturated in the laboratory and were shear under submorged conditions. Hie results of tests are b^ed on 80 percent peak strengtii or ultimate strength, whichever is lower, and are attached. In addition, a shear was performed CMI an upper layer sample remolded to 90-percent ofthe laboratory standard with low confining pressure. TEST RESULTS Majdmum DeBSitv/Qptimum Moisture (ASTM:D-1557-07> Trench Depth in Feet Maximum Density fDCf) Optimum Moistiire (%) 3 1-3 124 12.0 In-Situ Drv Density/ Moisture Trench Depth in Feet Dry Density fDCf) Moisture (%) 1 3.5 114.0 6.1 3 4 114.1 6.0 3 9 113.7 5.8 Direct Shear Trench Deptii in Feet Cohesion (psf) Angle of Intemal Friction (degrees) 3 4 200 30 ALLOWABLE BEARING CAPACITY Reference: "Soil Mechanics in Engineering Practice", Terzaghi and Peck, 1967 pages 222 and 223. Bearing Material: compacted fill Properties: Wet Density (y) = 130 pcf Cohesion (C) * 200 psf Angle of Friction (^) = 30 degrees Footing Depth (D) = 2 feet Footing Width (8) 1.0 foot Factor of Safety = 3.0 Calculations - Ultimate Bearing Capacity from figure 33.4 on page 222 Nc= 30.14 Nq= 18.4 Ny = 22.4 Qu = 1.2 C Nc + y D Nq + 0.4 y B Ny (Square Footing) = 1.2 •200* 30.14+ 130*2* 18.4+ 0.4* ISC 1 *22.4 = 7233 + 4784 + 1164 = 13181 psf Allowable Bearing Capacity for Square Footing Qaii= Qu/F.S. = 4393 psf Use 1500 psf (Settlement Control) Qu = 1.0 C Nc + y D Nq + 0.5 y B Ny (Continuous Footing) = 1.0 * 200 * 30.14 + 130 * 2 * 18.4 + 0.5 * 130 * 1 * 22.4 = 6028 + 4784 + 1456 = 12268 psf Allowable Bearing Capacity for Continuous Footing CU= Qu/F.S. = 4089 psf Use 1500 psf (Settlement Control) Increases: 440 psf / ft In depth over 2 feet 0 psf / ft in depth over 1 foot Geotecrfinical Engineering Investigation 391 Tamarack Avenue Carlsbad, California Wbric Order 262310 STRATA - TECH, INC. ACTIVE RETAINING WALL PRESSURE Proposed Pool WALL Free Body Diagram PA H = Hc = 5 ft 2 ft a = 53.1 ° F.S. = 2.00 ym = 130 pcf C = 200 psf tp = 30° 0.13 kef 0.2 ksf •mtm CA. W = a + b a = 45° + 0^ / 2 Cm = C/F.S. - 0.1 ksf ^n, - tan"^ (tan ^ / F.S.) = 16.1 degrees D = ( H - Ho) tan ( 90° - a) = 2.26 ft L = {{H-Hc)^ + D^)"^ = 3.76ft W=:Ay„ = 0.5D(H + Hc)y^= 1.03kips/LF a = Cm L sin (90° + ^n,) / Sin ( a - 0„) = 0.6 kips/LF b = W-a= 0.43 kips/LF PA = b tan («- ^n,) = 0.32 kips/LF Design EFP = 2 PA / H ^ = 25.6 pcf Use 26 pcf (30 min.) Geotechnical Engineering Investigation 391 Tamarack Avenue Carisbad, California Wbric Order 262310 Geotechnical Engineering Investigation 391 Tamarack Avenue Carisbad, California STRATA' TECH, INC. STRATA-TECH, INC BEOCONSULTANTS APPENDIX B SPECIFICATIONS FOR GRADING SITE CLEARING AU existing vegetation shaU be stripped and hauled fi^om the site. PREPARATION AftCT the foundation for tiie fill has been cleared, plowed or scarified, it shall be disced or bladed until h is uniform and fi-ee from large clcxls, brought to a proper moisture content and compacted to not less than 90 percent of the maximum dry density in accordance with ASTM:D-1557-02 (5 layers - 25 blows per layer; 10 lb. hammer droj^d 18"; 4" diameter mold). MATERIALS On-site materials may t)e used for fill, or fill materials shall consist of materials qjproved by the Soils Engineer and may be obtained fixjm the excavation of banks, borrow pits or any other approved source. The materials used should be fi-ee of vegetable matter and other deleterious substances and ^U not contain rocks or lumps greater tiian 8 inches in maximum dimension. PLACING, SPREADING, AND COMPACTING HLL MATERL4LS Where natural slopes exceed five horizontal to one vertical, the exposed bedrock shall be benched prior to placing fiU. The selected fill material shall be placed in layers which, when compacted, shall not exceed 6 inches in thickness. Each layer shall be spread evenly and shall be thoroughly mixed during the spreading to ensure uniformity of material and moisture of each layer. Where moisture of the fill material is below the limits specified by the Soils Engin^r, water shall be added until the moisture content is as required to ensure tiiorough bonding and thorough compaction. Where moisture content of the fill material is above the limits specified by the Soils Engineer, the fill materials shall be aerated by blading or other satisfactory methods until the moisture content is as specified. After each layer has been placed, mixed and spread evenly, it shall be thoroughly compacted to not less than 90 percent ofthe maximum dry density in accordance with ASTM:D-1557-02 (5 layers - 25 blows per layer; 10 lbs. hammer dropped 18 inches; 4" diameter mold) or other density tests which will attain equivalent results. STRATA-TECH, INC BEOCONSULTANTS Compaction shaU be by sheepsfcx)t roller, multi-wheel pneumatic tire roller or other types of acceptable rollers. Rollers shall be of such design that they will be able to compact the fiU to the specified density. RoUing shall be accompUshed while the fill material is at the specified moisture content Rolling of each layer shall he continuous over the entu-e area and the roller shall make sufficient trips to ensure that the desired density has been obtained. ITie final surface of the lot areas to receive slabs on grade should be rolled to a dense, ^ooth surface. The outside of all fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment Compaction operations shall be continued until the outer 9 inches of the slope is at least 90 percent compacted. Compacting ofthe slopes may be progressively in increments of 3 feet to 5 feet of fill height as the fill is brought to grade, or after the fill is brought to its total height. Field density tests shall be made by the Soils Engineer of the compaction of each layer of fill. Density tests shaU be made at intervals not to exceed 2 feet of fiU height provided aU layers are tested. Where the sheepsfoot rollers are used, the soil may be disturbed to a deptii of several inches and density readings shall be taken in the compacted material betow the disturbed surface. When tiiese readings indicate that the density of any layer of fill or portion there is below the required 90 percent density, the particular layer or portion shaU be reworked until the required density has been obtained. The grading specifications should be a part of the project specifications. The Soil Engineer shall review the grading plans prior to grading. INSPECTION The Soil Engineer shaU provide continuous supervision of the site clearing and grading operation so tiiat he can verify the grading was done in accordance with the accepted plans and specifications. SEASONAL LIMITATIONS No fill material shall be placed, spread or rolled during unfavorable weather conditions. When work is interrupted by heavy rains, fiU operations shaU not be resumed until the field tests by the SoUs Engineer indicate tiie moisture content and density of the fill are as previously specified. EXPANSIVE SOIL CONDHIONS Whenever expansive soil conditions are encountered, the moisture content of the fill or recompacted soil shall be as recommended in the expansive soU recommendations included herewith. STRATA B e a c o N s •TECH U L T A N • , I N C r 8 714-521-5611 562-427-8099 FAX 714-521-2552 7372 Walnut Avenue, Unit F.Buena Park, California 90620 May 24,2011 W.0.262310 TcHiy Sfi«do 21 Woodcrest Irvine, California, 92603 Subject: Grading Plan Review and Groundwater Statement 391 Tamarack Avenue, Carlsbad, California. Gentlemen: Pursuant to your request, STRATATECH, Inc. has reviewed tiie grading plan for tiie site tiiat has been prepared by DMS consultants Drawing No 471 3a. . These plans are in conformance with the recommendations of the Geotechnical report for this site. The stormwater infiltration will consist of permeable pavements. The pavements wiU be located at finish grade approximately 1 foot above the existing grade. An exploratory boring drilled on August 3,2010 to 12-feet below existing grade revealed dry sand, and a lack of groundwater and confirms that the proposed groundwater infilti-ation system will be located at least 10-feet above the groundwater table. We appreciate this opportunity to be of service to you. Respectfully submitted: STRATA-TECH, Inc. Roland Acufla, PG Principal Larry Finlcy RCK 46606