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Home My WebLink AboutCT 01-05; CALAVERA HILLS VILLAGE W; INTERIM REPORT OF ROUGH (MASS) GRADING MODEL LOTS 16-19; 2004-02-26cTOJ-05 Geotechnucal Geologic Environmental 5741 Palmer Way • Carlsbad California 92008 • (760) 438-3155 • FAX (760) 931-0915 February 26, 2004 W.0. 3459-B,-SC Brookfield Homes 12865 Pointe Del Mar, Suite 200 Del Mar, California 92014 Attention Ms Dee Gallegos Subject Interim Report of Rough (Mass) Grading, Model Lots 16 through 19, Calavera Hills II, Village W, Carlsbad Tract 01-05, City of Carlsbad, San Diego County, California Dear Ms Gallegos In accordance with your request and authorization, GeoSoils, Inc (GSI) is presenting this interim report of rough grading Grading and processing of original ground within the subject. lots was observed and selectively tested by a representative of GSI during the earthwork phase of development for the subject property The scope of our services includes geotechnical observations during site grading, field density and laboratory testing, and preparation of this summary letter. Existing geotechnical documents, related to the site, are listed in Appendix A. General criteria related to the development of these building lots are presented in Appendix B SITE GRADING/FOUNDATION CONSTRUCTION The work performed to date is in general conformance with the recommendations contained in Our referenced report (GSI, 1999), and with the grading ordinance of the City of Carlsbad, San,Diego County, California. Field testing indicates that fills placed under the purview of this report have beeh' compacted to a minimum 9d percent relative compaction As-built fill thicknesses range from approximately 7 feet to 25 feet, with the maximum fill thickness generally not greater than 3 times the minimum fill thickness across • the pad area for agiven.lot. Laboratory .testing performed to date indicates that.the subject lots have a very low to low expansion potential (Expansion Index [E I] less than 50), in accordance with Table 18-I-B of the Uniform Building Code ([UBC], International Conference of Building Officials [ICBO], 1997). Testing also indicates that sulfate exposure on the subject lots is negligible, in accordance with Table 19-A-4 of the UBC (ICBO, 1997) S ';' : '•' - ( Based on a review of the fôundatioi plans,.'repared by Davidson Reinforcing Company (DRC, 2003), for this project (GSI, 2004), and the as-built conditions noted above, foundation systems may be designed and constructed in accordance with criteria for Category I' soil cbnditiohs, shown on Sheet CVR of DRC (2003). The structural engineer should review the criteria for "category ito verify these conditions are still applicable to -the design, from a structural engineering standpoint. A final compaction report of rough grading and improvements construction, including observations and testing results for rough grading, utilities, and driveway/parking areas, is forthcoming. . . . . . 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 ours tudy 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 standard s* 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, or their inaction, or work performed when GSI is not requested. to be onsite to evaluate if our ., recommendations have been properly implemented.: Use of this report constitutes an agreement and consent by the user to all the limitations outlined above, notwithstanding any other agreements that may be in place. In, addition, this report may be subject to review by the controlling authorities The conclusions and recommendations presented herein 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. GSl'assumes no responsibility or liability for work, testing, or recommendations performed or provided by others, their inaction,' or work performed without the, benefit of geotechnical observation and testing services by GSI. Brookfield Homes • • . • •. 'S • W.O. 3459-B-SC Village W, Calavéra Hills II • • . ', February'26, 2004 FiIe:e:\wp9\3400\3459b.w.jro : . • .• • • Page 2 ' - •. GeoSoils, Inc.' ' • 5 The opportunity to be of service is greatly appreciated. If you have any questions, please do not hesitate to contact any of the undersigned. . Respectfully submitted, GeoSoils, Inc ; f - 'l ' iewed by rrE4/:jc-,' A' Robert G Crisman David W Skelly Engineering Geologit, 'i934— Civil Engineer, RCE 47857 RGC/DWS/JPF/jk Attachments Appendix A - References IN Appendix B -, Development Criteria Distribution (4) Addresse s CEG 0 • ,- - 0 • 0 0 •,•. - 0 Brookfield Homes - -- W0. 3459B-SC Village W, Calavera Hills II • -• • • 0, 0 • February 26, 2004 • 0 File e \wp9\3400\3459b w iro Page 3 GeeSoils, Inc. APPENDIX B DEVELOPMENT CRITERIA Slope Deformation Compacted fill slopes designed using customary factors of safety for gross or surficial stability and constructed in general accordance with the design specifications should be expected to undergo some differential vertical heave or settlement in combination with differential lateral movement in the out-of-slope direction, after grading. This post-construction movement occurs in two forms: slope creep, and lateral fill extension (LFE). Slope creep is caused by alternate wetting and drying of the fill soils which results in slow downslope movement. This type of movement is expected to occur throughout the life of the slope, and is anticipated to potentially affect improvements or structures. (i.e., separations and/or cracking), placed near the top-of-slope, up to a maximum distance of approximately 15 feet from the top-of-slope, depending on the slope height. This movement generally results in rotation and differential settlement of improvements located within the creep zone. LFE occurs due to deep wetting from irrigation and rainfall on slopes comprised of expansive materials. Although some movement should be expected, long-term movement from this source may be minimized, but not eliminated, by placing the fill throughout the slope region, wet of the fill's optimum moisture content. It is generally not practical to attempt to eliminate the effects of either slope creep or LFE. Suitable mitigative measures to reduce the potential of lateral deformation typically include: setback of improvements from the slope faces (per the UBC and/or California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. All of these measures are recommended for design of structures and improvements. The ramifications of the above conditions, and recommendations for mitigation, should be provided to each homeowner and/or any homeowners association. . 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 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, and cause perched groundwater conditions. Graded slopes constructed utilizing onsite m'aieriàlswOuld be erosive.' rosiVe 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. Jute-type matting or other fibrous covers may aid in allowing the establishment of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to GeoSoils, Inc. :develop. A. rodent control program to prevent burrowing should be implemented. Irrigation of natural (ungraded) slope areas is generally not recommended. These recommendations regarding plant type, irrigation practices, and rodent control should be provided to each homeowner. Over-steepening of slopes should be avoided during building construction activities and landscaping. . . . . Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of, adverse performance of foundations, hardscape, and slopes. Surface drainage should be suffidentto prevent ponding of water anywhere on a lot, and especially near structures and tops of slopes. Lot surface drainage should be carefully taken into consideration during fine grading, landscaping, and building construction. Therefore, care should be taken that future landscaping or construction activities do not create adverse drainage conditions. Positive site drainage within lots and common areas should be provided and 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. In general, the area within. 5 feet around a structure should slope away from the structure. We recommend that unpaved lawn and landscape areas have a minimum gradient of 1 percent sloping- away from structures, and whenever possible, should be above adjacent paved areas. Consideration should be given to avoiding construction of planters adjacent to structures (buildings, pools, spas, etc.). 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 may 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.' Erosion. Control Cut and fill slopes will be subject to surficial erosion during and after grading. Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences for the temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Only the amount of irrigation necessary to sustain plant life should be provided. Over-watering the-landscape areas will adversely affect proposed site improvements. We would recommend that any proposed open-bottom, raised box 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 of the planter, could be installed to direct drainage away from structures or any exterior concrete Brookfield Homes . ' ' Appendix B FiIé:e:\wp9\3400\3459bw1r0 ' ' S ' Page 6 GeoSoils, Inc.. flatwork. If raised' box planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture barrier to prevent penetration of irrigation water into the subgrade Provisions should be made to drain the excess irrigation water from the planters without saturating the subgrade below or adjacent to the planters Graded 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 berecompacted to 90 percent minimum relative compaction. Gutters and Downspouts As previously discussed in the drainage section,.the installation of gutters and downspouts 'should be considered to collect roof water that may otherwise infiltrate the soils adjacent to the structures. If Utilized, the °downspouts should' be drained into PVC collector pipes or non-erosive devices that will carry the water away from the house. Downspouts and 'gutters are not a 'requirement; however, from' a geotechnical viewpoint, provided that positive drainage is incorporated into project design (as discussed previously) 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 may not be precluded from occurring in the future due to site irrigation, poor drainage conditions, or damaged utilities, and should be anticipated. 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. Site Improvements Recommendations for exterior concrete flatwork design and construction can be provided upon-request.. If in the future, any additional improvements (e.g.', pools, spas, etc.) are planned forthe site, recommendations concerning the geological or geotechnical aspects of design and construction of said im'pr'o'Jernents.could be prbvided 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 backfills. Brookfield Homes Appendix B Fi1e:e:\wp9\3400\3459bw1r0 Page 7 GeoSoiis, Inc. Tile Flooring Tile flooring can crack, reflecting 'cracks in the concrete slab below the tile, although small cracks in a conventional slab may not be significant. Therefore, the designer should consider additional steel reinforcement for concrete slabs-on-grade 'where tile will be 'placed. The 'tile installer should consider installation methods that reduce possible:. cracking of the tile such as slipsheets. Slipsheets or a vinyl crack isolation membrane (approved by the Tile Council of America/Ceramic Tile Institute) are recommended between tile and concrete slabs on grade Additional Grading This office should be notified in advance of any fill placement, supplemental regrading of the site, or trench backfilling after rough grading has been completed. This includes completion of grading in the street and parking areas and utility trench and retaining wall backfihls 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 V removal and recompaction of the subgrade materials would be recommended at that time. Footing trench spoil and any excess soils geierated from utility-trench excavations should be compacted to a minim,um'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. ' , Utility Trench Backfill. , . '' V ' ' V • ' 1. ' 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. Brookfjeid Homes V • ' V 'V Apperdix B File:e:\wp9\3400\3459b.w.jr0 • V ' ' . Page 8 GeoSoils, Inc. L. • ' V. , V ,' , , . ' " . " . " V. • 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 .be'neath 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. 3: ' All trench excavations should conform to CAL-OSHA and local safety codes. 4. Utilities crossing grade beams, perimeter beams, or footings should either pass below'the footing or grade beam utilizing a hardened collar or foam spacer, or pass through the footing or grade beam in accordance with the recommendations of the structural engineer. 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. During significant excavation (i.e., higher than 4 feet). •• 'During placement of sübdrains, toe drains, or other subdrainage devices, prior to placing fill and/or backfill. ' After excavation of building footings; retaining wall footings, and free standing walls footings, prior to the placement of reinforcing steel or concrete. Prior to pouring any slabs or flatwork, after presoaking/presaturation of building pads and other flatwork subgrade, before the placement of concrete, reinforcing steel, capillary break (i.e., sand, pea-gravel, etc;), or vapor barriers (i.e., visqueen, etc.). S During retaining wall subdrain installatioh prior to backfill placement. •. During placement of backfill for'àréa drain, interior plumbing, utility line trenches, and retaining wall backfill. • •: • During slope construction/repair. S , • . • When any unusual soil conditions are encountered during any construction operations, subsequent tothe issuance of this report., • Brookfield Homes . ' S • S • , Appendix B FiIe:e:\wp9\3400\3459b.w.iro : , ' S , • Pace 9 GeoSóils, Inc. ' • • S • I • ' S S • ' • .. •'., S When any developer-or hom - walls, etc., are constri. • A report of .9eotechnicai conclusion of each of 'H - documentation of site work;'ar 'i-I , AM M • '• • dv€nents, such as flatwork,spas, pools, sting should be provided at the der to provide concise and clear vith code requirements. The design civil engineer, sion designer, architect, landscape architect, wall designer, etc;, t1e'd iiimendations provided herein, incorporate those plans, and by explicit reference, make this report lar PNREVIEW* Final project plans should to construction, so that construction is in accordance witiconciions and rec. ommendations of this report Based on our review, supplemental Ior further geotechnical studies may be warranted. • ' ":, '. T : • . . • •' • • • • • • • S ••--- •-r• - • , •'ç • • •1 ,4#;'': 4 •• •'- • .• .-•• • • • - •-•• S• Brookfield Homes • • ' • -:- -,': , Appendix B File e \wp9\3400\3459b w iro Page 10 GeoSoilS, Inc. - ' ' .. . ,. . • - •' • . ' HUN'SAfl VR &ASSOCIATES V V V• , PLANNING V ENGINEERING V , SURVEYING V V •. ,, V V V V V V V V IRVINE V V V V V V V V V V May 4, 2004 LOS ANGELES RIVERSIDE. SAN DIEGO City of Carlsbad V 1635 Faraday Avenue Carlsbad, CA 92008 , V Attn: ' Grading Inspector. 'Subject: V ' Rough Grade Lot Certification- V V V Project Dwg 408-4A Title: V , Calavera Hills Village W V ' VV VV V V V V Tract: .01-05 • .0 V ' V V V V V: , V , VVV V • Model Lots: , 16 through 20 I hereby approve the rough grading for the referenced model lots in accordance with my responsibilities under the City of Carlsbad Grading and Excavation Code Rough Grading has been completed within 0 1 of a foot of the approved grading plan designed elevations The condition of the lots at the time of our deificationheçk. Was, dirt with no swale, retaining walls, or landscaping. V L.S. 6854 46854 Exp. 9/30/04 Daniel P. Smith V V , HunsakerV& Assocates San Diego, Inc. V DAVE HAMMAR V 'V V V V • • V V • V , V V V LEX WILLIMAN • ALISAVIALPANDO V V V V, V • V VV V ' • V V V V , DAN SMITH V V V V V V V RAY MARTIN V V V V V V V V 10179 Huennekens St. V V V V V San Diego, CA 92121 ' V ' • V V (858) 558V4500 PH (858) V ' V V • ' V V V V V 558-1414 FX VV V V, V • '' V www.HunsakerSD Corn V • V V V , • V • V V V V • Info@HunsakerSD corn' V V V EP:kc k:1941\2004\f49,doc ' V V V V W.O. 1941V53 5/4/04 10:35 AM V F. - 4 4 S. -- U -. • BUILDING PLAN - AS-GRADED LOT NO. ELEVATION ELEVATION VARIAN CE J16 -18r60 71K 17 . ' 18260 18255 005 18 .1870O 187O1'0.01 'k 19 i92oo iig- 20 - 195.40 195.41.-+0.01 4 4 4 --.. • ----, - 4.. I- . -1 4 ••-- .• •. - .. + - - -4 - - - -• - 4 - I I - + S - + •.• - . . + EP:kc k:\1941004\I49.doc I w.0. 1941-53 5/4/04 1034 AM 4 +4 - .. - .- . .4 .- - ,-