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HomeMy WebLinkAboutCT 01-01; CALAVERA HILLS VILLAGE; REPORT OF ROUGH GRADING; 2003-06-24I 5741 Palmer Way • Carlsbad, California 92008 • (760) 438-3155 • FAX (760) 931-0915 'June 24, 2003 W.O. 3459-B-SC Calavera Hills II, LLC 2727 Hoover Avenue National City, California 91950 Attention: Mr. Don Mitchell Subject: Report of Rough Grading, Calavera Hills, Village L-2, Lots 1 through 14, Carlsbad Tract 01-01, City of Carlsbad, San Diego County, California Dear Mr. Mitchell: This report presents a summary of the geotechnical testing and observation services provided by GeoSoils, Inc. (GSl), during the rough earthwork construction phase of development at the subject site. Earthwork commenced in January, 2003, and was generally completed in May, 2003. This report does not include utility and pavement construction testing and observations. A report of observation and testing services for such work will be provided under separate cover. PURPOSE OF EARTHWORK The purpose of grading was to prepare relatively level pads for the construction of 14 residential structures and access roadways. Cut-and-fill grading and drill-and-shoot blasting techniques were utilized to attain the desired graded configurations. Cut lots and the cut portion of transition lots were overexcavated in order to provide for more uniform foundation support. Existing topsoils and colluvium were removed to suitable bedrock material and recompacted. The grading plan for this portion of Calavera Hills II, Village L-2, prepared by O'Day Consultants, dated January 29, 2003, is included with this report as Plate 1. EARTH MATERIALS Subsurface geologic conditions exposed during the process of rough grading were observed by a representative of GSI. Earth materials onsite generally consist of dense gran itic/metavol can ic: rock with a thin, discontinuous surficial veneer of topsoil/colluvium. Dense surficial outcrops of granitic/volcanic bedrock were noted throughout the area. GROUNDWATER Naturally occurring groundwaterwas not encountered during rough grading of the building pads and should not affect the poposed building construction provided that the recommendations contained in this report and/or provided by GSI are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Based on the fractured and dense nature of the granitic/metavolcanic bedrock, perched groundwater conditions may develop in the future due to excess irrigation, homeowner altered drainage, or damaged utilities, and should be anticipated. Should manifestations of perched conditions (i.e., seepage) develop in the future, this office could assess the conditions and provide mitigative recommendations as necessary. A discussion of near surface slope subdrainage is presented in our referenced report on toe drains (GSl, 1998d), and is considered applicable with respect to this site. A discussion of other subdrainage is presented in a later section of this report. EARTHWORK CONSTRUCTION Earthwork operations have been completed in general accordance with the City of Carlsbad grading ordinance and the guidelines provided in the field by this office. Observations during grading included removals, overexcavation, and subdrain construction along with general grading procedures and placement of compacted fills by the contractor. Rough Grading Preparation of Existing Ground Deleterious material, such as concentrated organic matter and miscellaneous debris, were stripped from the surface and disposed of beyond the limits of grading for the subject area, prior to placing any fill. Loose surficial materials (i.e., existing topsoils and colluvium) were removed to expose competent bedrock in all areas to receive fill. In order to provide for more uniform support of structures, the cut portion of transition lots were overexcavated to a minimum depth of 3 feet below pad grade, then brought to grade with compacted fill. Cut lots exposing dense granitic/volcanic rock were overexcavated a minimum of 3 feet below pad grade in order to facilitate Calavera Hills II, LLC W.O. 3459-13-SC Calavera Hills, Village L-2 June 24, 2003 Fi1e:e:\wp9\3400\3459b1.12.rog Page 2 GeoSoils, Inc. foundation and utility construction. Generally, an attempt was made to slope the overexcavated bottom toward the Street area. Thus, subdrainage of these areas does not appear necessary at this time. In areas where conventional cut and fill grading techniques were not feasible due to rock hardness, drill-and-shoot blasting techniques were utilized. These techniques were used where dense, non-rippable rock occurred within a minimum of 3 feet of finished pad grade, and above local street elevations equivalent to approximately 1 toot below the lowest utility invert elevation. Blasting operations occurred in the general vicinity of Lots 1 and 6 through 14. Subsequent to completing removals, areas to receive compacted fill were scarified to a minimum depth of 12 inches, moisture conditioned to at least optimum moisture content, and then compacted to attain a minimum relative compaction of 90 percent. These areas were then brought to grade with fill compacted to a minimum 90 percent relative compaction. All processing of original ground in areas to receive fill, shown on Plate 1, was observed by a representative of GSI. Fill Placement Fill consisted of onsite and import materials which were placed in thin lifts, approximately 4 to 8 inches in thickness, brought to at least optimum moisture content, and compacted to attain a minimum 90 percent relative compaction. Compaction test results on fills are presented in the attached Table 1. Approximate as-built fill thicknesses are presented in the attached Table 2. The preparation of some of these materials including processing of shot rock and oversize rock through a rock crusher. This process generally produced "6-inch minus" material, in accordance with guidelines presented in GSI (2002). Rock fills were not placed within this site. Fill materials generated onsite, or within the larger Calavera Hills development, from either raw excavation or produced at the crusher site, have been placed in general accordance with recommendations presented in GSI (2002). An additional criteria, developed for this project during grading, has included gradation testing (in general accordance with ASIM D-422) of stockpiled materials produced from the rock crusher. This testing has been performed in order to determine the percentage of "fines" included in the stockpile material. For this project, "fines" are considered to be earth materials that are % inch in diameter, or finer. Suitable soil fills are considered to consist of earth materials with at least 40 percent finer than 3/4 inch (GSI, 2003). Calavera Hills ii, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 File:e:\wp9\3400\3459b1J2.rog Page 3 GeoSoils, Inc. PA Canyon Subdralns Prior to placement of fill, a canyon subdrain, consisting of 4-inch diameter (Schedule 40) perforated PVC pipe, embedded in crushed rock and wrapped in filter fabric, was placed within a natural drainage course in the general vicinity of Lots 1 through 3. Construction and placement of the subdrain was observed by a representative of this office and is in general accordance with GSI recommendations. Slopes Planned Slopes In general, graded slopes constructed under the purview of this report should perform / satisfactorily with respect to gross and surticial stability, provided that these slopes are properly maintained, and are subject to the prevailing semi-arid climatic conditions. Fill slopes constructed under the purview of this report were provided with a keyway excavated into suitable bedrock material in accordance with GSI recommendations. Cut slopes were constructed using cut and fill grading techniques and/or blasting, and exposed dense igneous and/or metavolcanic rock. Temporary Slopes - Temporary construction slopes may generally be constructed at a gradient of 1:1 (horizontal to vertical) or flatter in compacted fill, and 1/2:1 (horizontal to vertical) in suitable bedrock material (provided adverse geologic structures are not present as evaluated by GSI). Utility trenches may. be excavated in accordance with guidelines presented in Title 8 of the California Code of Regulations for Excavation, Trenches, and Earthwork with respect to Type B soil (compacted fill) and stable rock (bedrock). Construction materials and/or stockpiled soil should not be stored within 5 feet from the top of any temporary slope. Temporary/permanent provisions should be made to direct any potential runoff away from the top of temporary slopes. Natural Slopes Natural slopes should generally perform satisfactorily with respect to gross and surilcial stabilit, provided they are subject to the prevailing semi-arid climatic conditions. A detailed analysis of natural slope stability has been completed under separate cover (GSI, 1998c). Field Testing Field density tests were performed using the sand cone method (ASTM D-1 556) and nuclear method (ASTM D-2922). Tests taken for the entire Calavera Hills project were taken in consecutive numerical order. Only the test results for Village L-2 are presented in Table 1 at the end of this report. The approximate locations of field Calavera Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 FiIe:e:\wp9\3400\3459b1.12.rog Page 4 GeoSoils, Inc. density tests are shown on the Field Density Test Location Map, Plate 1, which utilizes the 1" = 40' scale grading plans (sheet 5), prepared by O'Day Consultants, as a base map. Field density tests were taken at periodic intervals and random locations to check the compactive effort provided by the contractor. Based on the operations observed, test results presented herein are considered representative of the fills observed under the purview of this repoft 3. Visual classification of the soils in the field, as well as random laboratory testing, was the basis for determining which maximum dry density value to use for a given density test. 4. Testing was performed on a full-time basis. LABORATORY TESTING Moisture-Density Relations The laboratory maximum dry density and optimum moisture content for each major soil type was determined according to Test Method ASTM D-1 557. The following table presents the test results: I MAXIMUM DRY DENSITY OPTIMUM MOISTURE SOIL TYPE (pcf) CONTENT (%) A:-D:ark Brown, Silty SAND 120.5 13.0 B - Light Brown, Silty SAND 128.0 10.0 D - Light Gray, Silty SAND 126.5 . 10.5 E - Dark Brown, Silty GRAVEL 130.0 11.0 F - Brown, Sandy GRAVEL 126.5 10.5 (processed material) Expansive Soils Expansive soil conditions have been evaluated for the site. Representative samples of soil near pad grade were recovered for classification and expansion testing. Expansion Index (E.I.) testing. was performed in general accordance with Standard 18-2 of the Uniform Building Code (UBC). Calavera Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 - File:e:\wp9\3400\3459b1.12.rog Page 5 - GeoSoils, Inc. Representative expansion indices indicate that site soils near pad grade, within the subject lots, are very low expansive (El. <5). A summary of soil expansion results are presented in the attached Table 2. Corrosion/Sulfate Testing Typical samples of the site materials were analyzed for corrosion/soluble sulfate potential. Soil sulfate testing indicates that the sulfate exposure to concrete is negligible, in accordance with Table 19-A of the UBC (1997). Alternative methods and additional comments may be obtained from a qualified corrosion engineer. Sieve Analysis - Sample gradation for various representative samples was determined in general accordance with ASTM Test Method D-422. Test results are presented as Plates B-i and - B-2 in Appendix B. RECOMMENDATIONS - FOUNDATIONS General The foundation design and construction recommendations are based on laboratory testing and engineering analysis of onsite earth materials by GSI. Recommendations for conventional or post-tension (PT) foundation systems are provided in the following sections. The foundation systems may be used to support the proposed structures, provided they are founded in competent bearing material. The proposed foundation systems should be designed and constructed in accordance with the guidelines contained in the UBC. All footing designs should be reviewed by the project structural engineer. Based on soil expansion potential and the as-built fill thicknesses (i.e., differential fill thickness exceeding 3:1, maximum to minimum, across the lot), conventional or PT foundations may be constructed. -- Conventional Foundation Design Conventional spread and continuous footings may be used to support the proposed residential structures provided they are founded entirely in properly compacted fill or other competent bearing material (i.e., bedrock). Footings should not simultaneously bear directly on bedrock and fill soils. Analyses indicate that an allowable bearing value of 2,000 pounds per square foot (psf) may be used for design of continuous footings per Table 3, and for design of isolated pad footings 24 inches square and 18 inches deep into properly compacted fill or bedrock. The bearing value may be increased by ½ for seismic or other Calavera Hills II, LLC WO;3459BSC Calavera Hills, Village L-2 June 24, 2003 FiIe:e:\wp93400\3459b1.l2.rog Page 6 GeoSoils, Inc. temporary loads. This value may be increased by 20 percent for each additional 12 inches in depth, to a maximum of 2,500 psf. No increase, in bearing, for footing width is recommended. For lateral sliding resistance, a 0.4 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load. Passive earth pressure may be computed as an equivalent fluid having a density of 300 pounds per cubic foot (pcf) with a maximum earth pressure of 2,500 psf. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. Footings should maintain a horizontal distance or setback between any adjacent slope face and the bottom outer edge of the footing. The horizontal distance may be calculated by using h/3 (where (h) is the height of the slope). The horizontal setback should not be less than 7 feet, nor need not be greater than 40 feet (per code). The setback may be maintained by simply deepening the footings. Flatwork, utilities, or other improvements within a zone of h/3 from the top of slope may be subject to lateral distortion. Footings, flatwork, and utility setbacks should be constructed in accordance with distances indicated in this section, and/or the approved plans. Provided that the recommendations contained in this report are incorporated into final design and construction phase of development, a majority (>50 percent) of the anticipated foundation settlement is expected to occur during construction. Maximum settlement is not expected to exceed approximately 1/2 inch and should occur below the heaviest loaded columns. Differential settlement is not anticipated to exceed 3/4 inch between similar elements, in a 40-foot span. Conventional Foundation/Concrete Slab Construction The following construction recommendations are based on generally very low to low expansive bearing soils and maximum fill thicknesses of less than approximately 30 feet. Conventional continuous footings should be constructed in accordance with recommendations presented in Table 3, and in accordance with UBC guidelines (1997). All footings should be reinforced per Table 3. Detached isolated interior or exterior piers and columns should be founded at a minimum depth of 18 inches below the lowest adjacent ground surface and tied to the main foundation in at least one direction with a grade beam. Reinforcement should be properly designed by the project structural engineer. Calavera Hills Ii, L.LC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 FIIe:e:\wp93400\3459b1.I2.rog Page 7 GeoSoils, Inc. A grade beam, reinforced as above and at least 12 inches square, should be provided across the garage entrances. The base of the reinforced grade beam should be at the same elevation as base of the adjoining footings. The residential floor and garage slabs should have a minimum thickness of 4 inches, in accordance with Table 3. Concrete used in floor slab construction should have a minimum compressive strength of 2,000 psi. Concrete slabs should be underlain with a minimum of 4 inches of sand. In addition, a vapor barrier consisting of a minimum of 1 0-mu, polyvinyl-chloride membrane with all laps sealed, should be provided at the mid-point of the sand layer. The slab subgrade should be free of loose and uncompacted material prior to placing concrete. Concrete floor slabs (residence and garage) should be reinforced per Table 3. All slab reinforcement should be supported to ensure proper mid-slab height positioning during placement of the concrete. "Hooking" of reinforcement is not an acceptable method of positioning. Presaturation is not considered necessary for these soil conditions; however, the moisture content of the subgrade soils should be equal to, or greater than, optimum moisture to a depth of 12 inches belOw the adjacent ground grade in the slab areas, and verified by this office within 72 hours of the vapor barrier placement. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction 90 percent of the laboratory standard, whether it is to be placed inside the foundation perimeter or in the yard/right-of-way areas. This material must not alter positive drainage patterns that direct drainage away from the structural areas and toward the street. Proposed pools and other appurtenant structures should consider that excavation difficulties will likely be encountered in some lots at depths greater than approximately 3 feet below existing building pad grades due to the presence of dense granitic rock. Please refer to Table 2 for a listing of lots with relatively shallow (i.e., <10 feet) fills. As an alternative, an engineered PT foundation system may be used. Recommendations for PT slab design are presented in the following section. PT Slab Foundation Systems 1. PT slabs may be utilized for construction of typical one- and two- story residential structures onsite. The information and recommendations presented in this section Calavera Hills ii, LLC W.O. 3459-B-SC Calavera Hills, Village L2 June 24, 2003 File:e:\wp9\3400\3459b1J2.rog Page 8 GeoSouts, Inc. are not meant to supercede design by a registered structural engineer or civil engineer familiar with PT slab design or corrosion engineering consultant. From a soil expansion/shrinkage standpoint, a fairly common contributing factor to distress of structures using PT slabs is a significant fluctuation in the moisture content of soils underlying the perimeter of the slab, compared to the center, causing a "dishing" or "arching" of the slabs. To mitigate this possible phenomenon, a combination of soil presaturati61n (if necessary, orafterthe project has been dormant for a period of time) and construction of a perimeter "cut off' wall grade beam may be employed. For very low to low (E.l.= 0 through 50) expansive soils, perimeter and mid span beams should be a minimum 12 inches deep below the lowest adjacent pad grade.- The perimeter foundations may be integrated into the slab design or independent of the slab. The perimeter beams should be a minimum of 12 inches in width. A vapor barrier should be utilized and be of sufficient thickness to provide an adequate separation of foundation from soils (10 mil thick). The vapor barrier should be lapped and adequately sealed to provide a continuous water-resistant barrier under the entire slab. The vapor barrier should be sandwiched between two 2-inch thick layers of sand (SE>30) for a total of 4 inches of sand. Isolated piers should be incorporated into the PT slab system. Specific soil presaturation for slabs is not required for very low expansive soils; however, the moisture content of the subgrade soils should be at or above the soils' optimum moisture content to a minimum depth of 18 inches below grade, depending on the footing embedment. PT slabs should be designed using sound engineering practice and be in accordance with the Post-Tension Institute (PTl), local, and/or national code criteria and the recommendations of a structural or civil engineer qualified in PT slab design. Alternatives to P11 methodology may be used if equivalent systems can be proposed which accommodate the angular distortions, expansion parameters, and settlements noted for this project. If alternatives to PTI are suggested by the structural consultant, consideration should be given for additional review by a qualified structural PT designer. Soil related parameters for PT slab design, are presented on the following: Calavera Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 FIIe:e:wp9\3400\3459b1J2.rog Page 9 GeoSoils, Inc. Perimeter Footing Embedment* 12" Allowable bearing value 1000psf** Modules of subgrade reaction 125 psi/Inch Coefficient of friction 0.35 Passive pressure 275 pcf Soil Suction (Pt) 3.6 Depth to Constant Soil Suction 5 feet Thornthwaite moisture -20.0 e, edge 2.5 em center 5.0 ,,edge 0.25 center 1.00 1inirnurn Slab Thickness 5 inches * Lab data indicates E.I. 0-50 for this site. **Bearing for slab on grade only, bearing value for interior or perimeter beams should be in accordance with parameters provided for conventional continuous and isolated spread footinos. Provided the recommendations contained in this report are incorporated into final design and construction phase of development, a majority (>50 percent) of the anticipated foundation settlement is expected to occur during construction. Maximum settlement is not expected to exceed approximately 1/2 inch and should occur below the heaviest loaded columns. Differential settlement is not anticipated to exceed 1/4 inch between similar elements, in a 20-foot span. Designers of PT slabs should review the parameters provided for PT slabs, and compare using a span distance of 5 feet, using a modules of subgrade reaction of 125 psi in their evaluation. In accordance with guidelines presented in the UBC, improvements and/or footings should maintain a horizontal distance, X, between any adjacent descending slope - face and the bottom outer edge of the improvement and/or footing. The horizontal distance, X, may be calculated by using X = h/3. X should not be less than 7 feet, nor need not be greater than 40 feet. X may be maintained by deepening the footings. Improvements constructed within a distance of h13 from the top of slope - may be subject to lateral distortion. Foundations for any adjacent structures, including retaining walls, should be deepened (as necessary) to below a 1:1 projection upward and away from any proposed lower foundation system. This recommendation may not be considered valid if the additional surcharge imparted by the upper foundation on the lower foundation has been incorporated into the design of the lower foundation. Additional setbacks, not discussed or superceded herein, and presented in the UBC are considered valid. Calavera Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 File:e:\wp9\3400\3459b1.12.rog Page 10 GeoSoils, Inc. EXTERIOR FLATWORK Exterior driveways, walkways, sidewalks, or patios, using concrete slab-on-grade construction, should be designed and constructed in accordance with the following criteria: Driveway slabs should be a minimum 4 inches in thickness; all other exterior slabs may be a nominal 4 inches in thickness. A thickened edge should be considered for all flatwork adjacent to landscape areas. Slab subgrade should be compacted to a minimum 90 percent relative compaction and moisture conditioned to at, or above, the soils optimum moisture content. The use of transverse and longitudinal control joints should be considered to help control slab cracking due to concrete shrinkage or expansion. Two of the best ways to control this movement are: 1) add a sufficient amount of properly placed reinforcing steel, increasing tensile strength of the slab such as 6x6, Wi .4xw1 .4); and/or 2) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. We would suggest that the maximum control joint spacing be placed on 5- to 8-foot centers, or the smallest dimension of the slab, whichever is least. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. Positive site drainage should be maintained at all times. Adjacent landscaping should be graded to drain into the street/parking area, or other approved area. All surface water should be appropriately directed to areas designed for site drainage. - 6. Concrete compression strength should be a minimum of 2,500 psi. CONVENTIONAL RETAINING WALLS/WALLS General Foundations may be designed using parameters provided in the Design section of Foundation Recommendations presented herein. Wall sections should adhere to the County of San Diego and/or City of Carlsbad guidelines. All wall designs should be reviewed by a qualified structural engineer for structural capacity, overturning, and seismic resistance stability per the UBC. The design parameters provided assume that onsite or equivalent low expansive soils are used to backfill retaining walls. If expansive soils are used to backfill the proposed walls within this wedge, increased active and at-rest earth pressures will need to be utilized for Calavera Hills Il, LLC S S W.O. 3459-B-SC calavera Hills, Village L-2 June 24, 2003 F11e:e:\wp9\3400\3459b1.I2.rog Page 11 GeoSoils, Inc. retaining wall design. Heavy compaction equipment should not be used above a 1:1 projection, up and away from the bottom of any wall. The following recommendations are not meant to apply to specialty walls (cribwalls, loffel, earthstone, etc.). Recommendations for specialty walls will be greater than those provided herein, and can be provided upon request. Some movement of the walls constructed should be anticipated as soil strength parameters are mobilized. This movement could cause some cracking dependent upon the materials used to construct the wall. To reduce wall cracking due to settlement, walls should be internally grouted and/or reinforced with steel. Restrained Walls Any retaining walls that will be restrained prior to placing and compacting backfill material, or that have re-entrant or male corners, should be designed for an at-rest equivalent fluid pressures of 60 pcf, plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Building walls below grade should be water-proofed or damp-proofed, depending on the degree of moisture protection desired. Refer to the following section for preliminary recommendations from surcharge loads. Cantilevered Walls These recommendations are for cantilevered retaining walls up to 15 feet high. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An empirical equivalent fluid pressure (EFP) approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are provided for specific slope gradients of the retained material. These do not include other superimposed loading conditions such as traffic, structures, seismic events, or adverse geologic conditions. SURFACE SLOPE OF EQUIVALENT FLUID RETAINED MATERIAL WEIGHT P.C.F. HORIZONTAL TO VERTICAL 1SIect Vans Inw ExnnsIvø Sblh Level I 35 The equivalent fluid density should be increased to 60 pcf for level backfill at the angle point of the wall (corner or male re-entrant) and extended a minimum lateral distance of 2H on either side of the corner. Traffic loads within a 1:1 projection up from the wall heel, due to light trucks and cars, should be considered as a load of 100 psf per foot in the upper 5 feet of wall in uniform pressure. For preliminary design purposes, footing loads within a Calavara Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 FiIe:e:\wp9\34003459b1.I2.rog Page 12 GeoSoils, Inc. 1:1 backfill zone behind wall will be added to the walls as 1/3 of the bearing pressure for one footing width, along the wall alignment. Sound Walls Foundations for top of slope sound walls, using concrete block construction, may be constructed in accordance with conventional foundation recommendations presented in this report. Foundations should maintain a minimum lateral distance of 7 feet from the outside bottom edge of the wall footing to the face of any adjacent slope. Wall Backfill and Drainage All retaining walls should be provided with an adequate gravel and pipe back drain and outlet system to prevent buildup of hydrostatic pressures, and be designed in accordance with the minimum standards presented herein. Retaining wall drainage and outlet systems should be reviewed by the project design civil engineer, and incorporated into project plans. Pipe should consist of schedule 40 perforated PVC pipe. Gravel used in the back drain systems should be a minimum of 1 cubic foot per lineal foot of %- to 1 ½-inch clean crushed rock encapsulated in filter fabric (Mirafi 140 or equivalent) additional gravel may be warranted depending on wall height and the nature of the wall backcut. Perforations in pipe should face down. The surface of the backfill should be sealed by pavement, or the top 18 inches compacted to 90 percent relative compaction with native soil. Proper surface drainage should also be provided. As an alternative to gravel back drains, panel drains (Miradrain 6000, Tensar, etc.) may be used. Panel drains should be installed per manufacturers' guidelines. Regardless of the - back drain used, walls should be water-proofed where they would impact living areas, or where staining would be objectionable. Wall Footing Transitions Site walls are anticipated to be supported on footings designed in accordance with the recommendations in this report. Wall footings may transition from bedrock to fill. If this condition is present, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of bedrock materials, as measured for a distance of 2H from the transition in the direction of the wall. Overexcavations should be completed for a minimum lateral distance of 2 feet beyond the footing, measured perpendicular to the wall. b) Increase of the amount of reinforcing steel and wall detailing (i.e., expansion joints or crack control joints) such that a angular distortion of 1/360 for a distance of 2H on either side of the transition may be accommodated. Expansion joints should be sealed with a flexible grout. Calavera Hills It, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 Fi1e:e:\wp9\3400\3459b1.12.rog Page 13 GeoSoils, Inc. c) Embed the footings entirely into native formational material. If transitions from cut to fill transect the wall footing alignment at an angle of less than 45 degrees (plan view), the designer should follow recommendation "a" (above,) and until such transition is between 45 and 90 degrees to the wall alignment. PAVEMENTS Pavement design for streets has not been performed to date. Concrete driveway pavements outside the public right of way maybe constructed per the exterior concrete slab recommendations presented in this report. DEVELOPMENT CRITERIA Graded Slope Maintenance and Planting Water has been shown to weaken the inherent strength of all earth materials. Slope stability is significantly reduced by overly wet conditions. Positive surface drainage away from graded slopes should be maintained and only the amount of irrigation necessary to sustain plant life should be provided for planted slopes. Over-watering should be avoided as it can adversely affect site improvements. Graded slopes constructed within and utilizing onsite materials would be erosive. Eroded debris may be minimized and surficial slope stability enhanced by establishing and maintaining a suitable vegetation cover soon after construction. Compaction to the face of fill slopes would tend to minimize short-term erosion until vegetation is established. Plants selected for landscaping should be light weight, deep rooted types that require little water and are capable of surviving the prevailing climate. Utilizing plants other than those recommended above will increase the potential for perched water to develop. These recommendations regarding plant type and irrigation practices should be provided to each homeowner. Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon request. If in the future, any additional improvements are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. This office should be notified in advance of any fill placement, grading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfllls. Calavera Hilts II, LLC W.O. 3459-13-SC Calavera Hills, Village L-2 June 24, 2003 File:e:\wp9\3400\3459b1.I2.rog Page 14 GeoSoils, Inc. Footing Trench Excavation All footing excavations should be observed by a representative of this firm subsequent to trenching and prior to concrete form and reinforcement placement. The purpose of the observations is to verify that the excavations are made into the recommended bearing material and to the minimum widths and depths recommended for construction. If loose or compressible materials are exposed within the footing excavation, a deeper footing or removal and recompaction of the subrade materials would be recommended at that time. Footing trench spoil and any excess soils generated from utility trench excavations should be compacted to a minimum relative compaction of 90 percent if not removed from the site. Trenching Considering the nature of the onsite soils, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls at the angle of repose (typically 25 to 45 degrees) may be necessary and should be anticipated. All excavations should be observed by one of our representatives and minimally conform to CAL-OSHA and local safety codes. Drainage Positive site drainage should be maintained at all times. Drainage should not flow uncontrolled down any descending slope. Water should be directed away from foundations and not allowed to pond and/or seep into the ground. Pad drainage should be directed toward the street or other approved area(s). Although not a geotechnical requirement, roof gutters, down spouts, or other appropriate means should be utilized to control roof drainage. Down spouts, or drainage devices should outlet a minimum of 5 feet from structures or into a subsurface drainage system. Areas of seepage may develop due to irrigation or heavy rainfall and should be anticipated. Minimizing irrigation will lessen this potential. If areas of seepage develop, recommendations for minimizing this effect could be provided upon request. Subsurface and Surface Water Subsurface and surface water are not anticipated to affect site development, provided that the, recommendations contained in this report are incorporated into final design and construction and that prudent surface and subsurface drainage practices are incorporated into the construction plans. Perched groundwater conditions along zones of contrasting permeabilities should not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities. Should perched groundwater conditions develop, this office could assess the affected area(s) and provide the appropriate recommendations to mitigate the observed groundwater conditions. Groundwater conditions may change with the introduction of irrigation, rainfall, or other factors. Calavera Hills II, LLC . W.O. 345913SC Calavera Hills, Village L-2 ' June 24, 2003 Fi1e:e:\wp9\3400\3459b1.12.rog Page 15 GeoSoils, Inc. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the landscape areas could adversely affect proposed site improvements. We would recommend that any proposed open-bottom planters adjacent to proposed structures be eliminated, for a minimum distance of 10 feet. As an alternative, closed-bottom type planters could beutilized. An outlet placed in the bottom of the planter, could be installed to direct drainage aay from structures or any exterior concrete flatwork. The slope areas should be planted with drought resistant vegetation. Consideration should be given to the type vegetation chosen and their potential effect upon -surface improvements (i.e., some trees will have an effect on concrete flatwork with their extensive root systems). From a geotechnical standpoint leaching is not recommended for establishing landscaping. If the surface soils are processed for the purpose of adding amendments, they should be recompacted to 90 percent minimum relative compaction. UtilIty Trench Backfill All interior utility trench backfill should be brought to at least 2 percent above optimum moisture content and then compacted to obtain a minimum, relative compaction of 90 percent of the laboratory standard. As an alternative for shallow (12-inch to 18-inch) under-slab trenches, sand having a sand equivalent value of 30 or greater may be utilized and jetted or flooded into place. Observation, probing and testing should be provided to verify the desired results. Exterior trenches adjacent to, and within areas extending below a .1:1 plane projected from the outside bottom edge of the footing, and all trenches beneath hardscape features and in slopes, should be compacted to at least 90 percent of the laboratory standard. Sand backfill, unless excavated from the trench, should not be used in these backfill areas. Compaction testing and observations, along with probing, should be accomplished to verify the desired results. All trench excavations should conform to CAL-OSHA and local safety codes. PLAN REVIEW Final foundation and improvement plans should be submitted to this office for review and comment, as they become available, to minimize any misunderstandings between the plans and recommendations presented herein. In addition, foundation excavations and earthwork construction performed on the site should be observed and tested by this office. If conditions are found to differ substantially from those stated, appropriate recommendations would be offered at that time. Calavera Hills II, LLC . W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 F1Ie:e:\wp9\3400\3459b1.12.rog Page 16 GeoSolis, 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., After excavation of building footings, retaining wall footings, and free standing walls footings, prior to the placement of reinforôing steel or concrete. During retaining wall subdrain installation, prior to backfill placement. During placement of backfill for area drain, interior plumbing, utility line trenches, and retaining wall backfill. After presoaking/presaturation of building pads and other flatwork subgrade, prior to the placement of reinforcing steel or concrete. During slope construction/repair. When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. During homeowner construction of any site improvements. 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 is expressed or implied. Standards of practice are subject to change with time. GSI assumes no responsibility or liability for work or testing performed by others. In addition, this report may be subject to review by the controlling authorities. Calavera Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 File:e:\wp9\3400\3459b1.I2.rog Page 17 GeoSoils, Inc. Respectfully su GeoSolls, Inc. di"ED Geoz No j Robert G. Crisman \ Project Geologist, CEG C AL\Z REGULATORY COMPLIANCE Removals, processing of original ground cuts, and fills have been observed and compaction testing performed under the purview of this report have been completed using the selective testing and observations services of GSl. Earthwork was found to be in compliance with the Grading Code of the City of Carlsbad, California. Our findings were made and recommendations prepared in conformance with generally accepted professional engineering practices, and no further warranty is implied nor made. This report is subject to review by the controlling authorities for this project. GSI should not be held responsible nor liable for work, testing, or recommendations performed or provided by others. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to call our office. Re 'ewed by: David W. Skelly P Civil Engineer, RCE 47857 oVESio o. RCE47857 Exp./t OF sJOF C RGC/DWS/JPF/jk Attachments: Table 1 - Field Density Test Results Table 2- Lot Characteristics Table 3- Foundation Construction Recommendations Appendix - Referenceè Plate 1 - Field Density Test Location Maps Distribution: (4) Addressee Calavera Hills II, LLC W.O. 3459-B-SC Calavera Hills, Village L-2 June 24, 2003 File:e:\wp9\3400\3459b1.I2.rog Page 18 GeoSoils, Inc. I •• . . •. Table FIELD DENSITY TEST RESULTS •. TEST NO. DATE TEST LOCATION TRACT NO. ELEV OR DEP TH (ft) MOISTURE CONTENT (%) DRY DENSI1Y (pcf) REL COMP (%) TEST METHOD SOIL TYPE 289 1/17/03 Slope Area Lot Village L-2 404.0 14.2 109.5 90.9 . ND A 290 1/17/03 Slope Area Lot 3 Village L-2 406.0 14.5 111.8 92.8 ND A 291 1/17/03 Slop eArea Lot 3 Village L-2 409.0 13.9 112.3 93.2 ND A 292 1/17/03 Slope Area Lot 2 Village L-2 411.0 13.7 110.4 91.6 ND A 293 1/17/03 Slope Area Lot Village L-2 413.0 14.0 113.9 945 ND A 294 1/17/03 Slope Area Lot 2-3 Village L-2 415.0 13.6 111.1 92.2 ND A- 295 1/17/03 Slope Area Lot Village L-2 410.0 13.2 109.3 90.7 ND 296 1/17/03 Slope Area Lot l Village L-2 420.0 14.8 109.4 90.8 ND 315 1/22/03 North Side Of Slopes Village L-2 414.0 11.3 114.1 909 ND 0 316 1/22/03 North Side Of Slope 3 Village L-2 413.0 11.5 114.7 91.3 Sc 0 322 1/23/03 North Side Of Lot 9 .. Village -2 414.0 13.8 1103 91.5 Sc A 323 1/23/03 North Side Of Lot Village L-2 416.0 14.3 109.7 91.7 SC A 324 1/23/03 North Side Of Lot 4 Village L-2 418.0 13.5 109.3 90.7 Sc A 325 1/23/03 North Side Of Lot 5 Village L-2 420.0 14.1 109.5 90.8 ND 329 1/24/03 Lot 11 ...Village L-2. 407.0 11.8 114.2 90.9 ND 330 1/24/03 Lot 11 Village L-2 409.0 11.5 113.8 90.6 ND D. 357 1/20/03 - Lot Village L-2 418.0 13.9 109.8 91.1 ND L358. - 1/20/03 . . _. Lot Village L-2 414.0 14.4 108.7 90.2 - . ND A 367 1/22/03 Rear Lot 5 Village L-2 411.0 14.6 109.4 90.8 ND A 368 1/22/03 Rear Lot S 9-10 Village -2 .. 412.0 13.2 108.7. 90.2 ND A 369 1/22/03 Rear Lot 4 Village L-2 413.0 13.9 109.5 90.9 ND A 370 1/22/03 Rear Lot 7 Village L-2 415.0 15.7 110.4 91.6 ND A 371 1/22/03 Rear Lot Village L-2 417.0 15.7 110.4 91.6 ND A 372 1/22/03 Rear Lot 3 Village L-2 419.0 14.3 111.7 92.7 ND A L7j2 . .3/21/03 . Lot Village L-2 422.0 10.6 119.4 93.3 ND B 713 3/21/03 - Lot Village L-2 .420.0 11.4 118.2 92.3 ND B L 714 - 3/24/03 Lot Village L-2 420.0 - 11.1 119.8 94.7 ND F. 715 3/24/03 ._ _- - Lot Village L-2 422.0 11.4 119.1 .94.2.. -F--i 716 3/25/03. - Lot Village _-2 424.0 10.7 120.1 95.0 ND F 717 3/25/03 ...ot3 Village L-2 426.0 11.1 . 119.t94.4 ND F 718 3/26/03 .- . . Lot Village L-2 422.0 10.6 118.4 93.6 ND F 719 3/26/03 Lot Village L-2 424.0 10.9 117.9 93.2 ND F. - 860 . 4/9/03 Lot Village L-2 424.0 . 10.8 * 119.2 942 ND F 861.. 4/9/03.... - _....Lot6 Village L-2 423.0 - -11.2---- -118.0..... .93.3. ND F. 862 4/9/03 Lot Village L-2 423.0 11.1 118.8 93.9 ND 1029 5/14/03 Granite Cit 5+50 Village L-2 419.0 11.8 116.1 91.8 ND F 1030 5/14/03 Lot Village L-2 423.0 12.2 114.1 90.2 ND F 1031 5/14/03 Lot Village L-2 421.0 10.6 114.9 90.8 ND F 1032 5/14/03 Granite Crt 5+00 Village L-2 420.0 10.9 115.1 91.0 ND F 1080 5/22/03 Lot Village L-2 424.0 12.5 117.0 . 92.5 ND F 1081 5/22/03 Lot I Village L-2 426.0 11.6 115.2 91.1 ND F-..... 1082 5/22/03 Granite Ct 4+10 Village L-2 415.0 11.1 118.2 93.4 ND F 1083 5/22/03 2+20 Village L-2 406.0 10.2 117.8 93.1 ND F 1084 5/22/03 2+50 Village L-2 410.0 9.9 117.9 93.2 ND F .,1085 5/22/03 Lot . Village L-2 426.0 11.9 119.9 948 ND F 1086 5/22/03 Rec Lot VillageL-2 423.0 12.4 1164 92.0 _ND._.... F..... 1092 5/23/03 - Lot - - .Village.-2... 426.0 10.9 121.7 93.6 E - Calavera Hills Ii, LLC Calavera Hills, Village L-2 File: C:\excetables\3400\3459b.L2 GeoSoils, Inc. W.O. 3459-B-SC :-'June 20 03 -- Page 1. - 5 - •S Table 1 FIELD DENSITY TEST RESULTS TEST NO. DATE TEST LOCATION TRACT NO. ELEV OR MOISTURE CONTENT DEPTH DRY DENSITY REL COMP TEST METHOD SOIL TYPE 1093 5/23/03 Lot 1 Village L-2 426.0 11.3 123.6 95.1 . ND E/ 1094 1 5/23/03 Lot Village L-2 -. 427.0 11.6 122.6 94.3 ND :( 1095 5/23/03 Lot p----' -Village L-2 419.0 10.8 121.2 93.2 ND E. 1096 5/23/03 Lot 10 - - Village L.2 415.0 11.5 120.8 92.9 ND E. 1103 5/27/03 Lot Village L-2 420.0 12.2 119.9 92.2 ND E1 1104 5/27/03 Lot 10 Village L-2 416.0 .,...-.1.1.1 119.3 92.2 ND E 1105. 5/27/03 Lot Village L-2 426.0 -10.7. _123.0 94.6 - ND E 1106 5/27/03 Lot Village L-2 422.0 10.9 - 120.8 92.9 ND E 1107 5/27/03 Lot Village L-2. 417.0 11.3 . 121.9 91.9 . ND E 1110 5/28/03 Lot 11 Village L-2 412.0 '"11.8 119.2 91.7 - ND E 1127 5/30/03 Lot 1 Village L-2 FG 11.2 118.4 93.6 ND F 1128 5/30/03 Lot Village L-2 FG 10.4 .118.7. 93.8 ND F 1129 5/30/03 .0t3 Village L-2 FG 10.2 119.2 94.2 ND F. 1130 5/30/03 Lot Village L-2 FG 11.1 117.6 93.0 ND F 1131 5/30/03 Lot Village L-2 FG . 10.4 . .117.5 92.9 ND F 1144 6/2/03 Lot Village L-2 FG .12.1. .._121.9 93.8 ND E 1145 6/2/03 Lot 7 Village L-2 FG 10.8 120.3 92.5 ND 1146 6/2103 Lot 8 Village L-2 FG 11.2 124.9 96.1 ND 1147 6/2/03 Lot Village L-2 FG 10.2 123.5 95.0 ND E5 1148 6/2/03 Lot 10 . Village L-2 . FG 9.9 118.8 91.0 ND 1149 6/2/03 Lot 11 Village L-2 FG 10.4 120.4 92.6 ND E 1150 6/2/03 Lot 14 Village L-2 410.0 11.4 119.0 91.5 ND E. 1151 6/2/03 Lot 13 Village L-2 410.0 10.7 117.. 90.3 ND E1 1152 6/2/03 Lot 12 Village L-2 410.0 10.8 117.5 904 ND E 1153 6/2/03 Lot 14 Village L-2 412.0 11.0 118.4 91.1 ND E1 1154 6/2/03 Lot 13 Village L-2 413.0 11.4 117.9 90.7 ND E 1155 6/2/03 Lot 12 Village L-2 413.0 10.9 120.1 92.4 ND 1156 6/2/03 Lot 13 Village L-2 412.0 11.4 1_ 91.8 ND E 1157 6/2/03 Lot 12 Village L2 412.0 12.0 _17.4_ 90.3 ND 1166 6/3/03 Rec Area Village L-2 413.0 12.6 1_ 90.2 ND 1167 6/3/03 Lot 12 Village L-2 415.0 11.9 1_ 91.8 ND E. 1168 6/3/03 Lot 14 Village L-2 FG 10.4 117.1 90.1 ND E 1169 6/3/03 Lot 13 Village L-2 FG _ 11.2 119.3 91.8 ND E 1170 6/3/03 Lot 12 Village L-2 116.8. 923 ND F 1171 6/3/03 Granite Ct 4+90 Village L-2 422.0 10.8 115.0 90.9 ND F 1172 p1 6/3/03 Granite Ct 3+00 Village L-2 415.0 FG ..11.1 11.7 118.5 93.7 ND F 173 6/3/03 Granite Ct 1+60 Village L-2 411.0 11.2 115.7 91.5 ND F Legend FG = Finish Grade ND = Nuclear Densometer - SC = Sand Cone S - Calavera Hills II, LLC Calavera Hills, Village L-2 File: C:\excl\tables\3400\3459b.L2 GeoSoits, Inc. TABLE 2 :.... ., •.. LOT CHARACTERISTICS. . . . LOT : (per QBC Standard 18-2) EXPANSION INDEX.'SOLUBLE EXPANSION. POTENTIAI)1:...(ppm) SULFA SULFATE •. EXPOSURE DEPTH OF FILL (RANGE IN . FT.) FOUNDATION . CATEGORY 1 <5 Very Low 0.007 Negligible 3-11 (8-11)m 1 2 <5 Very Low 0.007 Negligible 7-17 1 3 . <5 Very Low 0.007 Negligible 8-20 1 4 <5 Very Low 0.007 Negligible 7-18 1 5 . <5 Very Low 0.0064 Negligible 7-14 1 6 <5 Very Low 0.0064 Negligible 4-12 1 7 <5 Very Low 0.0064 Negligible 3-13 (3-5)m 1 8 <5 Very Low 0.0064 Negligible 5-8 1 9 <5 Very Low 0.0064 Negligible 3-4 1 10 <5 Very Low 0.0064 Negligible 3-4 1 11 <5 Very Low 0.0061 Negligible 3-4 1 12 <5 Very Low 0.0061 Negligible 3-4 1 13 <5 Very Low 0.0061 Negligible 3-4 1 14 <5 Very Low 0.0061 Negligible 3-4 1 (1) Per Table 18-I-B of the Uniform Building Code (1997 ed.) Z Per Table 19-A-4 of the Uniform Building Code (1997 ed.) Estimated depth of fill beneath the building footprint. (4) Foundations should be constructed in accordance with recommendations for the specific categories noted above and presented in Table 3. GeoSoils, Inc. Ici::i.i*I CONVENTIONAL PERIMETER FOOTINGS, SLABS, AND EXTERIOR FLAT'NORK FOR CALAVERA HILLS, VILLAGE L-2 MINIMUM INTERIOR EXTERIOR FOUNDATION FOOTING SLAB REINFORCING INTERIOR SLAB UNDER-SLAB GARAGE SLAB. FLATWORK CATEGORY SIZE THICKNESS STEEL REINFORCEMENT TREATMENT REINFORCEMENT REINFORCING I 12" Wide 4 Thick 1- #4 Bar Top #3 Bars @ 2' Sand Over 6"x 6" None x and Bottom 24" o.c. 10-Mil Polyvinyl (10/10) 12° Deep Both Directions Membrane Over WWF 2" Sand Base II 12" Wide 4" Thick 2- #4 Bars Top #3 Bars @ 2" Sand Over 6"x 6° 6° x 6" x and Bottom 18" o.c. 10-Mil Polyvinyl (6/6) - (10/10) 18" Deep Both Directions Membrane Over WWF WWF 2' Sand Base III 12" Wide 4" Thick 2- #5 Bars Top #3 Bars @ 2° Sand Over Same as 6" x 6" x and Bottom 18° o.c. 10-Mil Polyvinyl Interior Slab (6/6) 24° Deep Both Directions. Membrane Over WWF 2" Sand Base Category I: Max. Fill Thickness is less than 20' and Expansion Index Is less than or equal 1050 and Differential Fill Thickness Is less than 10' (see note 1). Category II: Max. Fill Thickness is less than 50 and Expansion Index is less than or equal to 90 Differential Fill Thickness Is between 10 and 20' (see note 1). Category III: Max. Fill Thickness exceeds 59, Expansion Index exceeds 90 but is less than 130, gr Differential Fill Thickness exceeds 20 (see note 1). Notes 1. Post tension (PT) foundations are required where maximum fill exceeds 5Cr, the ratio of the maximum fill thickness to the minimum fill thickness exceeds 3:1. Consideration should be given to using post tension foundations where the expansion index exceeds 90. Footing depth measured from lowest adjacent subgrade. Allowable soil bearing pressure is 2,000 PSF. - Concrete for slabs and footings shall have a minimum compressive strength of 2,000 PSI (2,500 PSI for exterior flatwork), or adopted UBC mm.. at 28 days, using 5 sacks of cement Maximum Slump shall be 5". Visqueen vapor barrier not required under garage slab. However, consideration should be given to future uses of the slab area, such as room conversion and/or storage of moisture-sensitive materials. Isolated footings shall be connected to foundations per soils engineer's recommendations (see report). Sand used for base under slabs shall be very low expansive, and have SE > 30. Additional exterior tiatwork recommendations are presented in the text of this report. All slabs should be provided with weakened plane joints to control cracking. Joint spacing should be in accordance with correct industry standards and reviewed by the project structural engineer. APPENDIX REFERENCES GeoSoils, Inc., 2003, Memorandum, "General discussion of fill quality, Calavera Hills II, Carlsbad, California," W.O. 3459-132-SC, dated May 20. 2002, Review of grading and trench backfill recommendations, Calavera Hills II, Carlsbad tract 00-02, Drawing 390-90, City of Carlsbad, San Diego County, California, W.O. 2863-A-SC, August 16. 1999, Update of geotechnicalreport, Calavera Hill, Village L-2, City of Carlsbad, California," W.O. 2748-A-SC, dated October 15. 1998a, Lack of paleontological resources, Carlsbad tract nos. 83-19, PUD 56, and 83-32, PUD 62, Carlsbad, San Diego County, California, W.O. 2393-B-SC, dated January 21. 1998b, Preliminary review of slope stability, Calavera Hills, Villages 'Q" and "T", City of Carlsbad, California, W.O. 2393-B-SC, dated February 16. 1998c, Review of slope stability, Calavera Hills, Villages "Q" and "T," City of Carlsbad, California, W.O. 2393-B-SC, dated June 24. 1998d, Toe drain recommendations, Calavera Hills, Village T, City of Carlsbad, California, W.O. 2393-B-SC, dated September 30. Hunsaker & Associates San Diego, Inc., 1997b, Plans for the grading of Calavera Hills Village "Q", Carlsbad tract 83-32, Sheets 1-8, Drawing no. 303-2A, Project no. 2.89.33, dated November 17. Southern California Soil and Testing, Inc., 1992, Interim report of as built geology field observations and relative compaction tests, proposed College Boulevard improvements and Village El, Carlsbad, California, SCS&T 9121081 1988, Supplemental soil investigation, Calavera Hills Village Q and T, College Boulevard, Carlsbad, California, Job no. 8821142, Report no. 1, dated October 6. 1984, Report of geotechnical investigation for Village Q, Calavera Hills subdivision, Carlsbad, Job no. 14112, Report no.4, dated January 10. 1983a, Report of geotechnical investigation for Village Q, Calavera Hills subdivision, Carlsbad, Job no. 14112, Report no.4, dated January 10. 1983b, Report of preliminary geotechnical investigation for the Calavera Hills areas El, E2, H, I, K, and P through Z2, Carlsbad, Job no. 14112, Report no.1, dated July 29. GeoSoils, Inc.