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HomeMy WebLinkAboutCT 83-19; CALAVERA HEIGHTS, VILLAGE Q; REPORT OF ROUGH GRADING; 1998-09-02REPORT OF ROUGH GRADING CALAVERA HILLS, VILLAGE Q, LOTS 104 THROUGH 124 (INCLUDING MODEL LOTS) BLUFF COURT, TALUS WAY AND TAMARACK AVENUE, STATION 119+80 TO 131+00 CITY OF CARLSBAD, CAUFORNIA FOR CYPRESS VALLEY LLC 2727 HOOVER AVENUE NATIONAL CITY, CALIFORNIA 91950 W.O. 2393-B-SC SEPTEMBER 2,1998 Geotechnical • Geologic • Environmental 5741 Palmer Way • Carlsbad, California 92008 • (760)438-3155 • FAX (760) 931-0915 September 2,1998 W.O. 2393-B-SC Cypress Valley LLC 2727 Hoover Avenue National City, California 91950 Attention: Mr. Tliom Fuller Subject: Report of Rough Grading, Calavera Hills, Village Q, Lots 104 througii 124 (including Model Lots), Bluff Court, Talus Way and Tamarack Avenue, Station 119+80 to 131 +00, City of Carlsbad, California Dear Sir: Tliis report presents a summary of the geotechnical testing and observation services provided by GeoSoils, Inc. (GSI) during the rough earthwork phase of development at the subject site. Earthwork commenced on February 2,1998 and was generally completed on April 28,1998. Utility and pavement construction is in progress as ofthe date ofthis report and is therefore not included under the purview of tliis report. PURPOSE OF EARTHWORK The purpose of grading was to prepare relatively level pads for the construction of 21 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 plans for this portion of Calavera Hills, Village Q, prepared by Hunsaker & Associates Inc., San Diego, dated October 30,1997, are included with this report as Plates 1 and 2. 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 granitic 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 groundwater was not encountered during rough grading ofthe building pads and should not affect the proposed 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 sulDsurface drainage practices are incorporated into the construction plans. Based on the fractured and dense nature of the granitic/volcanic bedrock, perched groundwater conditions may develop in the future due to excess irrigation, homeowner altered drainage or damaged utilities. Should manifestations of perched conditions (i.e., seepage) develop in the future, this office could assess the conditions and provide mitigative recommendations as necessary. 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: 1. 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. 2. Loose surficial materials (i.e., existing topsoils and colluvium) were removed to expose competent bedrock in all areas to receive fill. 3. 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 foundation and utility construction. Where possible, an attempt was made to slope the overexcavated bottom toward the street area. Subdrainage of these areas does not appear necessary at this time. 4. 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 Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 Flle:e:\wp7\2300\2393b.ror Page 2 GeoSoils, Inc. of three feet of finish pad grade and above local street elevations equivalent to approximately 1 foot below the lowest utility invert elevation. Shot rock generated from the blasting operations was exported to rock fill areas outside the subject area. Blasting operations occurred in the general vicinity of Lots 104-108,110-113 and 120-122; within Tamarack Avenue stations 121 +00 to 129+00; and Bluff Court stations 10+00 to 12+00 and 14+00 to 14+50. 5. 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. 6. All processing of original ground in areas to receive fill, shown on Plates 1 and 2, was observed by a representative of GSI. Fill Placement: Fill consisted of onsite and import materials which were placed in thin lifts, approximately four to eight 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. Canyon subdrains were not necessary, based on the natural topography and overall fill depths. However, slope subdrainage was constructed and is discussed in the following section. Slopes Planned Slopes: In general, graded slopes constructed under the purview of this report should perform satisfactorily with respect to gross and surficial stability, provided that these slopes are properly maintained. Fill slopes constructed under the pun/iew of this report were provided witii a keyway excavated into suitable bedrock material in accordance with recommendations presented in SCST (1988) and as provided in the field by this office. Cut slopes were constructed using cut and fill grading techniques and/or blasting, and expose dense igneous and/or metavolcanic rock. A detailed analysis of slope stability has been completed under separate cover (GSI, 1998a). Temporary Slopes: Temporary construction slopes may generally be constructed at a gradient of 1:1 (horizontal to vertical) or flatter in compacted fill, and V^•.^ (horizontal to vertical) in suitable bedrock material (provided adverse geologic structures are not present). Utility trenches Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 3 GeoSoils, Inc. may be constructed 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 perform satisfactorily with respect of gross and surficial stability. A detailed analysis of slope stability has been completed under separate cover (GSI, 1998). Slope Subdrainage: Subdrains, consisting of perforated plastic pipe (Schedule 40) embedded in gravel then wrapped in filter fabric, were placed in perimeter fill slope keys beneath lots 109 through 111 and lots 112 through 114. Approximate drain locations and drain outlets are shown on Plates 1 and 2. As discussed in the groundwater section of this report, perched groundwater conditions may develop due to future irrigation, rainfall, homeowner altered site drainage or other conditions. Subdrain systems are recommended for all walls constructed below soil grades. While wall drains and key drains should perform adequately, the need for additional subdrainage onsite may not be precluded. Field Testing 1. Field density tests were performed using the sand cone method (ASTM D-1556-90) and nuclear method (ASTM D-2922). Test results are attached as Table 1 at the end of this report. The approximate locations of field density tests are shown on the Compaction Test Location Maps, Plates 1 and 2, which utilize the 1"=40' scale grading plans (sheets 3 and 4), prepared by Hunsaker & Associates, San Diego, Inc. as a base map. 2. 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 report. 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. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 4 GeoSoils, Inc. 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-1557-91. The following table presents the test results: SOIL TYPE MAXIMUM DRY DENSITY (PCF) OPTIMUM MOISTURE CONTENT (%) A - Dk Br Silty Sand (Topsoil) 123.0 12.0 B - Yellow Br Sandy Clay 109.5 19.5 C - Gray Br Silty Sand 126.0 11.5 D - Br Sandy Clay 118.0 14.5 E - Gray Br Silty Sand w/Gravel 130.5 10.0 F - Gray Br Silty Sand w/Gravel 135.0 8.0 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.l.) testing was performed in general accordance with Standard 18-2 of the Uniform Building Code. Representative expansion indices of less than 20 (very low) were determined for soils near pad grade within the subject lots. A summary of soil expansion results are present in the attached Table 2. Soil Sulfate The soluble sulfate content of site soils was evaluated. The results of this testing is presented in the attached Table 2. Based on the testing performed, sulfate resistant concrete is not required. 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 Cypress Valley LLC Calavera Hills, Village Q, Lots 104 -124 File:e:\wp7\2300\2393b.ror W.O. 2393-B-SC September 2,1998 Page 5 GeoSoils, Inc. conventional 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 Uniform Building Code. All footing designs should be reviewed by the project structural engineer. Conventional Foundation Design 1. 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. 2. Analyses indicate that an allowable bearing value of 2000 pounds per square foot may be used for design of continuous footings 12 inches wide and 12 inches deep 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 one- third for seismic or other temporary loads. This value may be increased by 20 percent for each additional 12 inches in depth, to a maximum of 2500 pounds per square foot. No increase, in bearing, for footing width is recommended. 3. 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. 4. Passive earth pressure may be computed as an equivalent fluid having a density of 300 pounds per cubic foot with a maximum earth pressure of 2500 pounds per square foot. 5. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 6. 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 utilities setbacks should be constructed in accordance with distances indicated in this section, and/or the approved plans. 7. Provided that the recommendations contained in this report are incorporated into final design and construction phase of development, a majority (>50 percent) ofthe anticipated foundation settlement is expected to occur during construction. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 6 GeoSoils, Inc. Maximum settlement is not expected to exceed approximately Vz-inch and should occur below the heaviest loaded columns. Differential settlement is not anticipated to exceed y4-inch between similar elements, in a 20 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. 1. Conventional continuous footings should be founded at a minimum depth of 12 inches below the lowest adjacent ground surface for one-story structures and 18 inches below the lowest adjacent ground surface for two-story structures. Interior footings may be founded at a depth of 12 inches below the lowest adjacent ground surface. Foundation widths may be constructed per the Uniform Building Code guidelines. All footings should be reinforced with a minimum of one No. 4 reinforcing bar placed near the top and one No. 4 reinforcing bar placed near the bottom of the footing. 2. 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 with a grade beam. Reinforcement should be properly designed by the project structural engineer. 3. 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. 4. The residential floor and garage slabs should have a minimum thickness of 4 inches. Concrete used in floor slab construction should be at least ASTM 520-C- 2500. 5. Concrete slabs should be underlain with a minimum of 4 inches of sand. In addition, a vapor barrier consisting of a minimum of 10-mil, 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. 6. Concrete floor slabs (residence and garage) may be minimally reinforced with 6- inch by 6-inch, No. 10 by No. 10 (6 x 6 - Wl .4 x W1.4) welded-wire mesh (i.e., industry standard). We understand that the client utilizes No. 3 reinforcement bars placed on 18-inch centers, in two horizontally perpendicular directions (i.e., long axis and short axis) as their company standard. This company standard should Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 Rle:e:\wp7\2300\2393b.ror Page 7 GeoSoils, Inc. exceed the industry standard and is also recommended by GSI. All slab reinforcement should be supported to ensure proper mid-slab height positioning during placement ofthe concrete. "Hooking" of reinforcement is not an acceptable method of positioning. 7. 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 belowthe adjacent ground grade in the slab areas, and verified by this office within 72 hours of the vapor barrier placement. 8. Soils generated from footing excavations to be used onsite should be compacted to a minimum relative compaction 90 percent ofthe 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. 9. Proposed pools and other appurtenant structures should consider that excavation difficulties will likely be encountered in lots at depths greater than approximately 3 feet below existing building pad grades due to the presence of dense granitic rock. 10. Rigid block wall designs located along the top of slopes should be reviewed by a soils engineer, prior to construction. 11. As an alternative, an engineered post-tension foundation system may be used. Recommendations for post-tensioned slab design are presented in the following Section. Post-Tensioned Slab Foundation Systems 1. Post-tensioned (PT) slabs may be utilized for construction of typical one (1) and two (2) story residential structures onsite. The information and recommendations presented in this section are not meant to supersede design by a registered structural engineer or civil engineer familiar with post-tensioned slab design or corrosion engineering consultant. 2. From a soil expansion/shrinkage standpoint, a fairly common contributing factor to distress of structures using post-tensioned 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 presaturation (if necessary, or after the project has been dormant for a period of time) and construction of a perimeter "cut off' wall grade beam may be employed. 3. For very low (E.l.= 0 through 20) expansive soils, perimeter and mid span beams should be a minimum 12 inches deep below lowest adjacent pad grade. The Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 8 GeoSoils, Inc. 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. In moisture sensitive slab areas, a vapor barrier should be utilized and be of sufficient thickness to provide a adequate separation of foundation from soils (10 mils, 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. 4. Isolated piers should be incorporated into the post tension slab system. 5. Specific soil presaturation for slabs is not required for very low expansive soils; however, the moisture content ofthe 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. 6. Post-tensioned slabs should be designed using sound engineering practice and be in accordance with the Post-Tension Institute (PTI), local and/or national code criteria and the recommendations of a structural or civil engineer qualified in post- tension slab design. Alternatives to PTI 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 post- tensioned slab design, are presented in the following: Perimeter Footing Embedment* 12" Allowable bearing value lOOOpsf** Modules of subgrade reaction 125 psi/inch Coefficient of friction 0.35 Passive pressure 275 pcf Soil Suction (PO 3.6 Depth to Constant Soil Suction 5 feet Thornthwaite moisture -20.0 e„ edge 2.5 e,„ center 5.0 my edge 0.25 my center 1.00 Minimum Slab Thickness 5 inches * Lab data indicates E.l. 0-20 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 footings. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills. Village Q, Lots 104 -124 September 2,1998 Flle:e:\wp7\2300\2393b.ror Page 9 GeoSoils, Inc. 7. Provided that the recommendations contained in this report are incorporated into final design and construction phase of development, a majority (>50 percent) ofthe anticipated foundation settlement is expected to occur during construction. Maximum settlement is not expected to exceed approximately y2-inch and should occur below the heaviest loaded columns. Differential settlement is not anticipated to exceed Vi-inch between similar elements, in a 20 foot span. Designers of PT slabs should review the parameters provided for post-tensioned slabs, and compare using a span distance of 5 feet, using a modules of subgrade reaction of 125 psi in their evaluation. 8. In accordance with guidelines presented in the Uniform Building Code, 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, where h is the height of the slope. 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 h/3 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 ofthe lower foundation. Additional setbacks, not discussed or superseded herein, and presented in the UBC are considered valid. 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: 1. Driveway slabs should be a minimum 4 inches in thickness; all other exterior slabs should be a nominal 4 inches in thickness. A thickened edge should be considered for all flatwork adjacent to landscape areas. 2. Driveway slabs may be reinforced with No. 6 by No. 6 (w2.9 by w2.9) welded wire mesh placed upon chairs to ensure mid-height positioning. Hooking or pulling of the reinforcement is not an acceptable method of placement. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 10 GeoSoils, Inc. 3. Slab subgrade should be compacted to a minimum 90 percent relative compaction and moisture conditioned to at or above the soils optimum moisture content. 4. 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 is; 1) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab, 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. 5. No traffic should be allowed upon the newly poured concrete slabs until they have been properly cured to within 75 percent of design strength. 6'. 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. 7. Concrete used to construct flatwork should be at least ASTM 520-C-2500. RETAINING 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 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. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 11 GeoSoils, Inc. 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 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 fifteen (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 RETAINED lUtATERIAL FLUID WEIGHT HORIZONTAL TO VERTICAL P.CF. (Verv Low to Low Expansive Soih Level 35 2 to 1 45 The equivalent fluid density should be increased to 60 pounds per cubic foot for level backfill at the angle point ofthe wall (corner or male re-entrant) and extended a minimum lateral distance of 2H (two times the wall height) 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 1:1 backfill zone behind wall will be added to the walls as Va of the bearing pressure for one footing width, along the wall alignment. 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 minimum standards presented herein. Retaining wall drainage and outlet systems should be reviewed by the project design civil engineer, and incorporated into project Cypress Valley LLC Calavera Hills, Village Q, Lots 104 -124 File:e:\wp7\2300\2393b.ror W.O. 2393-B-SC September 2,1998 Page 12 GeoSoils, Inc. plans. Pipe should consist of schedule 40 perforated PVC pipe. Gravel used in the back drain systems should be a minimum of 3 cubic feet per lineal foot of % to 1 Vz-inch clean crushed rock encapsulated in filter fabric (Mirafi 140 or equivalent). Perforations in pipe should face down. The surface ofthe 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. Retaining Wall Footing Transitions Sjte 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 two times the height of the wall 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. 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), then the designer should follow recommendation "a" (above) and until such transition is between 45 and 90 degrees to the wall alignment. PAVEMENTS Pavements may be designed and constructed in accordance with recommendations presented in GSI (1998b). Pavement design for streets not indicated in GSI (1998b) has not been performed to date. Concrete driveway pavements, a minimum 4 inches in thickness, may be constructed per the exterior concrete slab recommendations presented in this report. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 13 GeoSoils, Inc. 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. 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 be utilized. An outlet placed in the bottom ofthe planter, could be installed to direct drainage away from structures or any exterior concrete flatwork. The slope areas should be planted with drought resistant vegetation. Consideration should be given to the type of 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. 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. Roof gutters and down spouts should be considered to control roof drainage. Down spouts should outlet a minimum of three feet from proposed structures and/or in accordance with the recommendations of the design civil engineer. 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 be utilized. An outlet placed in the bottom Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 Flle:e:\wp7\2300\2393b.ror Page 14 GeoSoils, Inc. of the planter could be installed to direct drainage away from structures or any exterior concrete flatwork. Footing Trench Excavation All footing excavations should be observed by a representative ofthis 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 ofthe subgrade materials would be recommended at that time. All excavations should minimally conform to CAL-OSHA and local safety codes. Footing trench spoil and any excess soils generated from utility trench excavations should b.e compacted to a minimum relative compaction of 90 percent if not removed from the site. Additional Site Improvements 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. Proposed pools or other appurtenant structures should consider that excavation difficulties will likely be encountered in some lots (see Table 2) at depths greater than 3 feet below existing building pad grade. Rigid block wall designs located along the top of slopes should be reviewed by a soils engineer. Additional Grading This office should be notified in advance of any additional fill placement, regrading of the site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfills. All excavations should be obsen/ed by one of our representatives and conform to CAL-OSHA and local safety codes. Utility Trench Backfill 1. All interior utility trench backfill should be brought to at least two percent above optimum moisture content and then compacted to obtain a minimum relative compaction of 90 percent ofthe 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. Obsen/ation, probing and testing should be provided to verify the desired results. 2. 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 Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 15 GeoSoils, Inc. 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 obsen/ations, along with probing, should be accomplished to verify the desired results. 3. 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 obsen/ed and tested by this office. If. conditions are found to differ substantially from those stated, appropriate recommendations would be offered at that time. REGULATORY COMPLIANCE Removals, processing of original ground, cuts and fills have been obsen/ed and compaction testing performed underthe pun/iew ofthis report have been completed using the selective testing and observations services of GeoSoils, Inc. 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. GeoSoils, Inc. should not be held responsible nor liable for work, testing or recommendations performed or provided by others. Cypress Valley LLC W.O. 2393-B-SC Calavera Hills, Village Q, Lots 104 -124 September 2,1998 File:e:\wp7\2300\2393b.ror Page 16 GeoSoils, Inc. The opportunity to be of service is sincerely appreciated. If you should have any questions, please do not hesitate to call our office. Respectfully submitted, GeoSoils, Inc. Robert G. unsman Project Geologist, hn P. Franklin 1034 % David W. Skelly Civil Engineer, RCE Engineering Geologist, CEG~13i RGC/DWS/JPF/mo Attachments: Appendix - Refere Table 1- Field DensTty^Mfiesults Table 2- Lot Characteristics Plates 1 and 2 - As Graded Geotechnical Map Distribution: (4) Addressee Cypress Valley LLC Calavera Hills, Village Q, Lots 104 -124 Flle:e:\wp7\2300\2393b.ror GeoSoils, Inc. W.O. 2393-B-SC September 2,1998 Page 17 APPENDIX REFERENCES Cypress Valley LLC, 1998, Report of Rough Grading, Calavera Hills, Village Q Model Sites, including Bluff Court, Talus Way and Tamarack Avenue, Station 119+80 to 131 +00, City of Carlsbad, California, W.O. 2393-B-SC, June 1,1998. , 1997b, Plans forthe 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., 1988, Supplemental soil investigation, Calavera Hills Village Q and T, College Boulevard, Carlsbad, California, job no. 8821142, report no.l, dated October 6. , 1984, Report of geotechnical investigation for Village Q, Calavera Hills subdivision, Cartsbad, 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 forthe Calavera Hills areas El, E2, H, I, Kand Pthrough Z2, Carlsbad, job no. 14112, report no.l, dated July 29. GeoSoils, Inc., 1998a, Preliminary review of slope stability, Calavera Hills, Villages "Q" and "T", City of Carlsbad, California, W.O. 2393-B-SC dated February 16. , 1998b, Pavement design report. Talus Way, Bluff Court and Tamarack Avenue, Station 119+80 to 131 +00, Calavera Hills, Village Q, Carlsbad, California, W.O. 2393-B-SC, dated May 5,1998. GeoSoils, Inc. Table 1 FIELD DENSITY TEST RESULTS TEST NO. DATE TEST LOCATION ELEVATION OR DEPTH (ft.) MOISTURE CONTENT (%) DRY DENSITY (pcf) REWTJVE COMPACTION (%> TEST METHOD SOIL TYPE 218 04/09/98 VILLAGE Q BLUFF COURT 13+90 423.0 19.7 99.2 90.6 ND B 219 04/09/98 VILLAGE Q BLUFF COURT 13+00 417.0 13.6 112.4 91.4 ND A 220 04/09/98 VILLAGE 0 BLUFF COURT 11 +50 413.0 19.8 100.0 91.3 ND B 221 04/09/98 VILLAGE Q BLUFF COURT 12+50 417.0 13.1 111.7 90.8 ND A 222 04/09/98 VILLAGE Q BLUFF COURT 12+75 419.0 13.4 113.7 92.4 ND A 223 04/09/98 VILLAGE Q LOT 115 420.0 11.2 117.6 90.1 ND E 224 04/09/98 VILLAGE Q OPEN SPACE LOT 422.0 10.8 117.8 90.3 ND E 225 04/09/98 VILLAGE Q LOT 117 423.0 10.4 120.6 92.4 ND E 226 04/09/98 VILLAGE Q LOT 118 427.0 10.5 121.0 92.7 ND E 227 04/14/98 VILLAGE QT/U.US WAY 414.0 13.2 112.7 91.6 ND A 228 04/14/98 VILLAGE Q EASMENT 108-107 406.0 9.5 124.3 92.1 ND F 229 04/14/98 VILLAGE Q EASMENT 108-107 409.0 8.3 122.6 90.8 ND F 230 04/14/98 VILLAGE Q EASMENT 108-107 411.0 12.5 112.4 91.4 ND A 231 04/14/98 VILLAGE CLOT 109 400.0 13.9 112.2 91.2 ND A 232 04/14/98 VILLAGE 0 LOT 109 405.0 14.2 110.8 90.1 ND A 233 04/14/98 VILLAGE CLOT 110 395.0 12.6 110.7 90.0 ND A 234 04/14/98 VILLAGE CLOT 110 400.0 12.2 112.3 91.3 ND A 235 04/14/98 VILLAGE Q LOT 111 397.0 12.5 111.8 90.9 ND A 236 04/15/98 VILLAGE Q LOT 110 401.0 12.4 111.1 90.3 ND A 237 04/15/98 VILLAGE CLOT 112 402.0 13.3 110.8 90.1 ND A 238 04/15/98 VILLAGE Q LOT 111 404.0 13.8 110.7 90.0 ND A 239 04/15/98 VILLAGE CLOT 113 404.0 13.4 111.4 90.6 ND A 240 04/15/98 VILLAGE CLOT 111 408.0 13.9 111.9 91.0 ND A 241 04/15/98 VILLAGE Q LOT 114 407.0 13.6 110.8 90.1 ND A 242 04/15/98 VILLAGE CLOT 113 411.0 13.4 111.6 90.7 ND A 243 04/15/98 VILLAGE Q LOT 111 410.0 13.2 111.2 90.4 ND A 244 04/16/98 VILLAGE Q TAMARACK 128+40 420.0 15.9 110.7 93.8 ND D 245 04/16/98 VILLAGE 0 TAMARACK 127+00 417.0 14.7 112.3 95.2 ND D 246 04/16/98 VILUGE Q TAMARACK 125+50 400.0 16.2 111.9 94.8 ND D 247 04/16/98 VILLAGE Q TAMARACK 126+50 416.0 15.1 109.9 93.1 ND D 260 04/17/98 VILLAGE Q TALUS WAY 10+95 418.0 11.8 118.8 94.3 ND C 261* 04/20/98 VILLAGE Q TALUS WAY 10+30 422.0 12.9 103.6 84.2 ND A 261-A 04/20/98 VILLAGE Q TALUS WAY 10+30 422.0 12.6 110.9 90.2 ND A 262 04/20/98 VILLAGE Q LOT 120 425.0 13.1 112.3 91.3 ND A 263 04/20/98 VILLAGE Q LOT 122 428.0 12.2 113.8 92.5 ND A 264 04/20/98 VILLAGE Q LOT 124 429.0 11.9 114.2 90.6 ND C 265 04/20/98 VILLAGE CLOT 124 430.0 12.4 114.0 90.5 ND C 271 04/21/98 VILLAGE Q TAMARACK 121 +00 352.0 11.1 122.0 93.5 ND E 272 04/21/98 VILLAGE 0 TAMARACK 122+50 369.0 10.2 122.9 94.2 ND E 273 04/21/98 VILLAGE Q TAMARACK 124+00 386.0 12.4 116.7 92.6 ND C 274-S 04/21/98 VILLAGE Q LOT 109 SLOPE 410.0 11.8 114.9 91.2 ND C 275-S 04/21/98 VILLAGE Q LOT 110 SLOPE 406.0 11.3 114.2 90.6 ND C Cypress Valley LLC e:\excel\tables\2300\2393bq GeoSoils, Inc. W.O. 2393-B-SC Page 1 Table 1 FIELD DENSITY TEST RESULTS TEST NO. DATE TEST LOCATION ELEVATION OR DEPTH (ft.) MOISTURE CONTENT (%) DRY DENSITY (pcf) RELATIVE COMPACTION (%) TEST METHOD SOIL TYPE 276-S 04/21/98 VILLAGE Q LOT 110 SLOPE 408.0 11.5 114.5 90.9 ND C 277-S 04/21/98 VILLAGE Q LOT 110 SLOPE 400.0 11.6 113.5 90.1 ND C 278-S 04/21/98 VILLAGE Q LOT 111 SLOPE 411.0 11.5 113.8 90.3 ND C 279-S 04/21/98 VILLAGE Q LOT 112 SLOPE 411.0 11.2 114.7 91.0 ND c 280-S 04/21/98 VILLAGE Q LOT 113 SLOPE 406.0 12.0 114.2 90.6 ND c 281-S 04/21/98 VILLAGE Q LOT 113 SLOPE 410.0 11.6 114.4 90.8 ND c 282-S 04/21/98 VILLAGE Q LOT 114 SLOPE 405.0 11.9 114.5 90.9 ND c 283-S 04/21/98 VILLAGE Q LOT 110 SLOPE 404.0 11.7 113.5 90.1 ND c 285 04/21/98 VILLAGE Q TAMARACK 123+00 380.0 11.9 116.0 92.1 ND c 286 04/22/98 VILLAGE Q TAMARACK 120+60 357.0 12.8 116.4 92.4 ND c 287 04/22/98 VILLAGE Q TAMARACK 119+60 348.0 12.6 116.0 92.1 ND c 288 04/22/98 VILLAGE Q TAMARACK 121 +90 365.0 11.4 115.2 91.4 ND c 289 04/22/98 VILLAGE Q TAMARACK 124+80 399.0 11.9 115.7 91.8 ND c 290 04/22/98 VILLAGE Q TAMARACK 127+40 420.0 12.2 113.8 90.3 ND c 296 04/23/98 VILLAGE Q LOT 119 431.0 10.1 118.6 90.9 ND E 297 04/23/98 VILLAGE Q LOT 118 430.0 10.6 119.5 91.6 ND E 298 04/23/98 VILLAGE Q LOT 117 428.0 12.0 115.7 91.8 ND c 299 04/23/98 VILLAGE CLOT 116 426.0 11.8 116.3 92.3 ND c 300 04/23/98 VILLAGE Q OPEN SPACE 143 423.0 11.9 115.8 91.9 ND c 301 04/23/98 VILLAGE Q LOT 115 421.0 12.3 115.4 91.6 ND c 302 04/23/98 VILUGE CLOT 114 419.0 13.1 113.5 92.3 ND A 303 04/23/98 VILUGE CLOT 113 416.0 13.4 113.8 92.5 ND A 304 04/23/98 VILUGE Q LOT 112 414.0 12.8 113.3 92.1 ND A 305 04/23/98 VILUGE Q LOT 111 413.0 12.4 114.3 90.7 ND c 306 04/23/98 VILUGEQLOT110 413.0 11.8 113.9 90.4 ND c 307 04/23/98 VILUGE Q LOT 109 413.0 11.9 114.8 91.1 ND c 308 04/23/98 VILUGE Q TAMARACK 127+80 422.0 13.2 113.5 92.3 ND A 312 04/23/98 VILUGE 0 TAMARACK 129+00 424.0 11.2 118.6 90.9 ND E 313 04/24/98 VILUGE Q TAMARACK 130+00 422.0 10.5 120.3 92.2 ND E 314 04/24/98 VILUGE 0 TAMARACK 130+75 424.0 10.8 119.5 91.6 ND E 315 04/24/98 VILUGE Q TAMARACK 130+50 426.0 10.2 120.6 92.4 ND E 316 04/24/98 VILUGE Q LOT 107 413.0 11.7 115.5 91.7 ND c 317 04/24/98 VILUGE LOT 106 415.0 11.3 116.3 92.3 ND C 318 04/24/98 VILUGE LOT 105 417.0 11.5 116.0 92.1 ND C 319 04/24/98 VILUGE LOT 104 419.0 11.9 114.4 90.8 ND c 320 04/24/98 VILUGE LOT 108 413.0 12.2 115.4 91.6 ND c 321 04/24/98 VILUGE LOT 120 426.0 12.4 112.4 91.4 ND A 322 04/24/98 VILUGE LOT 121 429.0 12.8 113.8 92.5 ND A 323 04/24/98 VILUGE LOT 122 430.0 12.7 113.3 92.1 ND A 324 04/24/98 VILUGE LOT 123 431.0 12.9 115.3 93.7 ND A 325 04/24/98 VILUQE LOT 124 431.0 12.4 114.3 92.9 ND A Cypress Valley LLC e:\excel\tabies\2300\2393bq GeoSoils, Inc. W.O. 2393-B-SC Page 2 Table 1 FIELD DENSITY TEST RESULTS TEST DATE TEST LOCATION ELEVATION MOISTURE DRY RELATIVE TEST SOIL NO. CONTENT DENSITY COMPACTION METHOD TYPE DEPTH (ft.) iiiiiiiiiiii (pcf) 326 04/28/98 VILUGE Q TAMARACK 122+00 370.0 10.7 119.8 91.8 ND E 327 04/28/98 VILUGE Q TAMARACK 124+00 391.0 10.2 120.3 92.2 ND E 328 04/28/98 VILUQE Q TAMARACK 126+00 407.0 10.3 118.8 91.0 ND E 330 04/28/98 VILUGE Q TAMARACK 129+40 426.0 10.9 120.5 92.3 ND E 331 04/28/98 10+00 BLUFF COURT 406.0 11.1 113.5 90.1 ND C 332 04/28/98 11+00 BLUFF COURT 412.0 12.6 113.8 90.3 ND C 333 04/28/98 10+25 BLUFF COURT 409.0 11.3 114.4 90.8 ND C 334 04/28/98 13+00 BLUFF COURT 421.0 13.1 116.0 92.1 ND c 335 04/28/98 13+70 BLUFF COURT 426.0 13.3 114.2 90.6 ND c LEGEND . * - FAILED TEST A-RETEST ND - NUCLEAR DENSOMETER 8 - SLOPE TEST Cypress Valley LLC e:\excel\tables\2300\2393bq GeoSoils, Inc. W.O. 2393-B-SC Page 3 TABLE 2 LOT CHARACTERISTICS LOT # EXPANSION INDEX (per UBC standard 18-2) EXPANSION POTENTIAL"^) SOLUBLE SULFATE (ppm) SULFATE EXPOSURE*** DEPTH OF FILL (RANGE IN FT.) CLIENT FOUNDATION CATEGORY 104 15 Very Low 51 Negligible 3-4 l/ll 105 15 Very Low 51 Negligible 3-4 l/ll 106 15 Very Low 51 Negligible 3-4 l/ll 107 15 Very Low 51 Negligible 3-4 l/ll .108 10 Very Low 40 Negligible 3-5 l/ll 109 10 Very Low 40 Negligible 3-10 l/ll 110 10 Very Low 40 Negligible 4-15 l/ll 111 10 Very Low 40 Negligible 4-15 l/ll 112 10 Very Low 40 Negligible 3-6 l/ll 113 10 Very Low 40 Negligible 3-8 l/ll 114 12 Very Low 36 Negligible 3-6 l/ll 115 12 Very Low 36 Negligible 3-6 l/ll 116 12 Very Low 36 Negligible 3-6 l/ll 117 12 Very Low 36 Negligible 3-6 l/ll 118 12 Very Low 36 Negligible 3-6 l/ll 119 5 Very Low 14 Negligible 3-6 l/ll 120 5 Very Low 14 Negligible 3-4 l/ll 121 5 Very Low 14 Negligible 3-4 l/ll 122 5 Very Low 14 Negligible 3-4 l/ll 123 5 Very Low 14 Negligible 3-4 l/ll 124 5 Very Low 14 Negligible 3-4 l/ll Per Table 18-I-B of the Uniform Building Code (1997 ed.) '2' Per Table 19-A-4 of the Uniform Building Code (1997 ed.) Client Foundation Category added at request. Foundation should be constructed in accordance with recommendations developed by GSI and presented in this report. GeoSoils, Inc.