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HomeMy WebLinkAboutCDP 13-30; De Anda Residence; Coastal Development Permit (CDP) (7)GEpT-ECUNICAL UPDAIE.AND REV^LEW , PROPOSER DBVCLOPMil^f AJ 2425 JEFFERSON STREET^APJN 1^5-140-47) CARLSBAD SAN DlE^^cH^TYv/" FOR " —Ms: 1/ E R O N fCA-B E 1409 TURQUOISE DRIVE CARLSBAD, CALIFORNIA 92011 E-AfJDA W.O. 6612-A-SC OCTOBER 28, 2013 Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com October 28, 2013 W.O. 6612-A-SC Ms. Veronica De Anda 1409 Turquoise Drive Carlsbad, California 92011 Subject: Geotechnical Update and Review, Proposed Developmentof 2425 Jefferson Street (APN 155-140-41), Carlsbad, San Diego County, California Dear Ms. De Anda: In accordance with your request, GeoSoils, Inc. (GSI) has reviewed the referenced documents and reports (see Appendix - References) with respect to existing site conditions, planned additional construction/innprovements and current code requirements. Unless specifically superceded herein, the conclusions and recommendations presented in the updated preliminary report (GSI, 2008) remain valid and applicable. SITE CONDITIONS/PROPOSED DEVELOPMENT The property is a roughly rectangular-shaped lot bounded by Jefferson Street on the east, and adjacent residential properties to the south and north (under construction). Buena Vista Lagoon is located along the western edge of the property. The property itself consists of a relatively level pad area adjacent to Jefferson Street and a large natural slope, which descends approximately 50 feet westward from the pad area to Buena Vista Lagoon. Between the pad elevation of approximately 65 feet Mean Sea Level (MSL) and an elevation of approximately 25 feet MSL, the slope descends at an approximate gradient of 272:1 (horizontal: vertical [h:v]). From an elevation of 25 feet MSL to the lagoon level, the slope flattens to a gradient of approximately 472:1 (h:v). Existing improvements to the property consist of remnants of an old foundation system (concrete slab) and seepage pit, located in the northern portion ofthe existing pad area. Vegetation on the property in the vicinity of the pad area consists of some small trees and scattered grasses. Vegetation on the slope consists of primarily grasses. Drainage within the property is predominately by sheet flow directed toward Jefferson Street or down the slope face toward Buena Vista Lagoon. A site visit, completed in preparation of this report, has evaluated that conditions have not substantially changed from those previously evaluated. It is our understanding that the existing foundation will be demolished. The proposed site development will consist of preparing the pad for construction of a new, split level residential structure, including a lower level pool on the west side ofthe structure. Cut and fill grading techniques would be utilized to create design grades for the proposed single-family residential structure and pool. It is anticipated that the residential development will consist of a two-story structure with slab-on-grade and continuous footings, utilizing masonry and/or wood-frame construction. Building loads are assumed to be typical for this type of relatively light construction. The need for import soils is unknown. It is anticipated that sewage disposal will be tied into the regional municipal system. PREVIOUS WORK Previous geotechnical investigations and site work were completed by this office (GSI; 1993, 2003), with an updated evaluation completed in 2008 (GSI, 2008). These studies included surface observations and subsurface explorations, laboratory testing, engineering and geologic analysis, and the development of recommendations for earthwork and foundation design and construction, based on previously planned site development schemes. Based on our review of previously proposed development, it appears that site development concepts are similar to the currently proposed construction; however, standards of practice and Codes change with time. EARTHWORK CONSTRUCTION RECOMMENDATIONS General All grading should conform to the guidelines presented in Appendix Chapter J of the 2010 California Building Code ([2010 CBC], California Building Standards Commission [2010]), the City of Carlsbad, and as recommended by this office, in GSI (2008). When code references are not equivalent, the more stringent code should be followed. During earthwork construction, all site preparation and the general grading procedures ofthe contractor should be observed and the fill selectively tested by a representative(s) of GSI. If unusual or unexpected conditions are exposed in the field, they should be reviewed by this office and, if warranted, modified and/or additional recommendations will be offered. All applicable requirements of local and national construction and general industry safety orders, the Occupational Safety and Health Act (OSHA), and the Construction Safety Act should be met. It is GSI's understanding that the site is currently at, or very near, plan grades, and that additional grading will likely consist of the surficial remedial grading/processing recommended herein. Unless specifically superceded herein, the conclusions and recommendations presented in GSI (2008) remain valid and applicable. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28,2013 File:e:\wp9\6600\6612a.upg GcoSollS, IllC. Page 2 REMEDIAL EARTHWORK General A review of GSI (2008) generally indicated that unsuitable surficial deposits of existing fill, colluvium are to be removed to suitable formational soil and replaced with compacted fill. For the uniform support of structures, a 5-foot thick blanket of compacted fill was recommended. The minimum fill cap thickness may be revised to a minimum thickness of 4 feet, or 2 feet below the bottom of footing, whichever is greater. Alternatively, foundations for portions of the buildings foundation constructed within the existing, west facing descending slope may be deepened into the underlying formational soil, provided that all fill supporting the building pad is compacted to at least 95 percent relative compaction per ASTM D-1557. All building foundations should satisfy the setback requirements per Section 1808.7.2. Swimming Pool Based on the location ofthe pool, foundation support for the proposed swimming pool should be derived from suitable, underlying bedrock material. Foundation systems bearing on the existing sedimentary bedrock should consist of drilled pier foundations. Recommendations for a pier and grade beam foundation system are presented herein. However, the use of conventional foundations, sufficiently embedded into suitable formational soil, may be considered upon further review. Temporary Slopes Temporary slopes for excavations greater than 4 feet but less than 20 feet in overall height should conform to CAL-OSHA and/or OSHA requirements for Type "B" soils, provided water or seepage is not present. Temporary slopes, up to a maximum height of ±20 feet, may be excavated at a 1:1 (h:v) gradient, or flatter, provided groundwater and/or running sands are not exposed. Construction materials or soil stockpiles should not be placed within 'H' of any temporary slope where 'H' equals the height of the temporary slope. All temporary slopes should be observed by a licensed engineering geologist and/or geotechnical engineer prior to worker entry into the excavation. Based on the exposed field conditions, inclining temporary slopes to flatter gradients or the use of shoring may be necessary if adverse conditions are observed. If temporary slopes conflict with property boundaries, shoring or alternating slot excavations may be necessary. The need for shoring or alternating slot excavations should be further evaluated. Excavation Observation and Monitoring (All Excavations) When excavations are made adjacent to an existing improvement (i.e., utility, wall, road, building, etc.) there is a risk of some damage even if a well designed system of excavation Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28, 2013 File:e:\wp9\6600\6612a.upg GCOSoilS, IflC. Page 3 is planned and executed. We recommend, therefore, that a systematic program of observations be made before, during, and after construction to determine the effects (if any) of construction on existing improvements. We believe that this is necessary for two reasons: First, if excessive movements (i.e., more than y2-inch) are detected early enough, remedial measures can be taken which could possibly prevent serious damage to existing improvements. Second, the responsibility for damage to the existing improvement can be determined more equitably if the cause and extent ofthe damage can be determined more precisely. Monitoring should include the measurement of any horizontal and vertical movements of the existing structures/improvements. Locations and type ofthe monitoring devices should be selected prior to the start of construction. The program of monitoring should be agreed upon between the project team, the site surveyor and the Geotechnical Engineer-of-Record, prior to excavation. Reference points on existing walls, buildings, and other settlement-sensitive improvements. These points should be placed as low as possible on the wall and building adjacent to the excavation. Exact locations may be dictated by critical points, such as bearing walls or columns for buildings; and surface points on roadways or curbs near the top of the excavation. For a survey monitoring system, an accuracy of a least 0.01 foot should be required. Reference points should be installed and read initially prior to excavation. The readings should continue until all construction below ground has been completed and the permanent backfill has been brought to final grade. The frequency of readings will depend upon the results of previous readings and the rate of construction. Weekly readings could be assumed throughout the duration of construction with daily readings during rapid excavation near the bottom ofthe excavation. The reading should be plotted by the Surveyor and then reviewed by the Geotechnical Engineer. In addition to the monitoring system, it would be prudent for the Geotechnical Engineer and the Contractor to make a complete inspection ofthe existing structures both before and after construction. The inspection should be directed toward detecting any signs of damage, particularly those caused by settlement. Notes should be made and pictures should be taken where necessary. It is recommended that all excavations be observed by the Geologist and/or Geotechnical Engineer. Any fill which is placed should be approved, tested, and verified if used for engineered purposes. Should the observation reveal any unforseen hazard, the Geologist or Geotechnical Engineer will recommend treatment. Please inform GSI at least 24 hours prior to any required site observation. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad , October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSollS, IllC. Page 4 Preliminarv Grading Plan Review The preliminary grading plan prepared by Sampo Engineering, Inc. (SEI, 2013) has been reviewed with respect to the intent of the soils report and current site conditions. Based on our review, the plans appear to be in general accordance with the intent of the geotechnical report, provided that the conclusions and recommendations presented in this update evaluation are properly incorporated into the design and construction of the project. PRELIMINARY RECOMMENDATIONS - FOUNDATIONS/WALLS General Foundation design and construction shall be per the 2010 edition of the CBC (CBSC, 2010). Please note that GSI (2008) referenced the 2007 Code; however, while some section numbers have changed from the 2007 Code to the 2010 CBC (see following text/table, and CBSC [2010]), the geotechnical design parameters indicated in GSI (2008) are the same. Additional recommendations regarding peak horizontal ground acceleration and seismic surcharge are provided in the following sections. Foundation design should be re-evaluated at the conclusion of site grading/remedial earthwork for the as-graded soil conditions. Although not anticipated, revisions to these recommendations may be necessary. In the event that the information concerning the proposed development plan is not correct, or any changes in the design, location or loading conditions of the proposed structure are made, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and conclusions of this report are modified or approved in writing by this office. The information and recommendations presented in this section are not meant to supercede design by the project structural engineer or civil engineer specializing in structural design. Upon request, GSI could provide additional input/consultation regarding soil parameters, as related to foundation design. Unless specifically superceded herein, the conclusions and recommendations presented in GSI (2008) are considered applicable. Residence Based on the expansive potential of onsite soils, recommendation presented in GSI (2008) for conventional type foundation systems are provided. As indicated in GSI (2008) remedial earthwork shall consist of undercutting the building pad and placing the entire foundation system on a layer of compacted fill. Alternatively, foundations for portions of the buildings foundation constructed within the existing, west facing descending slope may be deepened into the underlying formational soil, provided that all fill supporting the Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28,2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IllC. Page 5 building pad is compacted to at least 95 percent relative compaction per ASTM D-1557. All building foundations should satisfy the setback requirements per Section 1808.7.2. Swimming Pool Minor cuts and fills are anticipated in order to create the pool pad area. Based on the location of the pool, foundation support for the proposed swimming pool should be derived from suitable, underlying bedrock material using a pier and grade beam foundation system. Recommendations for a pier and grade beam foundation system are presented herein. The use of conventional type foundations may be considered, upon further review and grading plan development. Pool foundations will require embedment into suitable formational soil and require setbacks to the face of slope per Section 1808.7.3 of the 2010 CBC (CBSC, 2010). Based on the overall height ofthe slope, and the depth to suitable formation beneath the slope face, setbacks on the order of 10 to 15 feet from the face of slope may be recommended. Retaining Walls Recommendations for the design and construction of retaining walls are presented in GSI (2008). For perimeter retaining walls located within the existing slope areas, foundation support may be derived from the underlying formational soil, as an alternative to removal and recompaction, and supporting foundations on a fill blanket. For wall foundations deepened into formation, all removal of unsuitable surficial soils shall be performed behind the wall(s) and any fills shall be compacted to at least 95 percent relative compaction per ASTM D-1557. All Wall foundations should satisfy the setback requirements per Section 1808.7.2. Seismic Shaking Parameters Based on the site conditions, the following table summarizes the site-specific design criteria obtained from the 2010 CBC (CBSC, 2010), Chapter 16 Structural Design, Section 1613, Earthquake Loads. The computer program Seismic Hazard Curves and Uniform Hazard Response Spectra, provided by the United States Geologic Survey (U.S.G.S.) was utilized for seismic design values. The short spectral response utilizes a period of 0.2 seconds. This application also produces seismic hazard curves, and uniform hazard response spectra. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson street, Carlsbad , October 28,2013 File:e:\wp9\6600\6612a.upg GCOSoUS, IttC. Page 6 CBC SEISMIC DESIGN PARAMETERS PARAMETER VALUE 2010 CBC REFERENCE Site Class D Table 1613.5.2 Spectral Response - (0.2 sec), S^ i.30g Figure 1613.5(1) Spectral Response - (1 sec), S, 0.49g Figure 1613.5(2) Site Coefficient, 1.0 Table 1613.5.3(1) Site Coefficient, F^ 1.51 Table 1613.5.3(2) Maximum Considered Earthquake Spectral Response Acceleration (0.2 sec), S^g 1.30g Section 1613.5.3 (Eqn 16-36) Maximum Considered Earthquake Spectral Response Acceleration (1 sec), S^^ 0.74g Section 1613.5.3 (Eqn 16-37) 5% Damped Design Spectral Response Acceleration (0.2 sec), Spg 0.86g Section 1613.5.4 (Eqn 16-38) 5% Damped Design Spectral Response Acceleration (1 sec), S^^ 0.49g Section 1613.5.4 (Eqn 16-39) GENERAL SEISMIC DESIGN PARAMETERS Distance to Seismic Source (Rose Canyon fault zone) 7.5 mi. (12.0 km) Upper Bound Earthquake (Rose Canyon fault zone) Mw6.9** Probabilistic Horizontal Ground Acceleration ([PHGA] 10% and 2% probability of exceedance in 50 years) 0.30g/0.39g ** International Conference of Building Officials (ICBO, 1998) Conformance to the criteria above for seismic design does not constitute any kind of guarantee or assurance that significant structural damage or ground failure will not occur in the event of a large earthquake. The primary goal of seismic design is to protect life, not to eliminate all damage, since such design may be economically prohibitive. Cumulative effects of seismic events are not addressed in the 2010 CBC (CBSC, 2010) and regular maintenance and repair following locally significant seismic events (i.e., M^^5.0) will likely be necessary. Peak Horizontal Ground Acceleration A probabilistic peak horizontal ground acceleration (PHGA) of 0.30 g was evaluated forthis site (GSI, 2008). This value was chosen as it corresponds to a 10 percent probability of exceedence in 50 years (or a 475-year return period). Per the 2010 CBC (CBSC, 2010), a PHGA of 0.39 was also evaluated. This value was chosen as it corresponds to a 2 percent probability of exceedence in 50 years (or a 2,475-year return period). Ms. Veronica De Anda 2425 Jefferson Street, Carlsbad File:e:\wp9\6600\6612a.upg GeoSoils, Inc. W.O. 6612-A-SC October 28, 2013 Page 7 Seismic Surcharge for Retaining Walls For engineered retaining walls that may pose ingress or egress constraints within 6 feet of a structure, GSI recommends that such walls be evaluated for a seismic surcharge (in general accordance with 2010 CBC requirements). The site walls in this category should maintain an overturning Factor-of-Safety (FOS) of approximately 1.25 when the seismic surcharge (increment), is applied. For restrained walls, the seismic surcharge should be applied as a uniform surcharge load from the bottom of the footing (excluding shear keys) to the top of the backfill at the heel of the wall footing. This seismic surcharge pressure (seismic increment) may be taken as 15H where "H" for retained walls is the dimension previously noted as the height of the backfill to the bottom of the footing. The resultant force should be applied at a distance 0.6 H up from the bottom of the footing. For the evaluation of the seismic surcharge, the bearing pressure may exceed the static value by one-third, considering the transient nature of this surcharge. For cantilevered walls the pressure should bean inverted triangular distribution using 15H. Reference for the seismic surcharge is Section 1802.2 of the 2010 CBC. Please note this is for local wall stability only. The 15H is derived from a Mononobe-Okabe solution for both restrained cantilever walls. This accounts for the increased lateral pressure due to shakedown or movement of the sand fill soil in the zone of influence from the wall or roughly a 45° - cj)/2 plane away from the back ofthe wall. The 15H seismic surcharge is derived from the formula: Ph = % • ah • YtH Where: Pj, = Seismic increment ai, = Probabilistic horizontal site acceleration with a percentage of "g" Y, = total unit weight (115 to 125 pcf for site soils @ 90% relative compaction). H = Height ofthe wall from the bottom ofthe footing or point of pile fixity. SOIL MOISTURE TRANSMISSION CONSIDERATIONS GSI has evaluated the potential for vapor or water transmission through the concrete floor slab, in light of typical floor coverings and improvements. Please note that slab moisture emission rates range from about 2 to 27 lbs/24 hours/1,000 square feet from a typical slab (Kanare, 2005), while floor covering manufacturers generally recommend about 3 lbs/24 hours as an upper limit. The recommendations in this section are not intended to preclude the transmission of water or vapor through the foundation or slabs. Foundation systems and slabs shall not allow water or water vapor to enter into the structure so as to cause damage to another building component or to limit the installation Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad , October 28, 2013 Flle:e:\wp9\6600\6ei2a.upg GcoSoilS, IllC. Page 8 of the type of flooring materials typically used for the particular application (State of California, 2013). These recommendations may be exceeded or supplemented by a water "proofing" specialist, project architect, or structural consultant. Thus, the client will need to evaluate the following in light of a cost vs. benefit analysis (owner expectations and repairs/replacement), along with disclosure to all interested/affected parties. It should also be noted that vapor transmission will occur in new slab-on-grade floors as a result of chemical reactions taking place within the curing concrete. Vapor transmission through concrete floor slabs as a result of concrete curing has the potential to adversely affect sensitive floor coverings depending on the thickness of the concrete floor slab and the duration of time between the placement of concrete, and the floor covering. It is possible that a slab moisture sealant may be needed prior to the placement of sensitive floor coverings if a thick slab-on-grade floor is used and the time frame between concrete and floor covering placement is relatively short. Considering the prior E.I. test results, and known soil conditions in the region, the anticipated typical water vapor transmission rates, floor coverings, and improvements (to be chosen by the Client and/or project architect) that can tolerate vapor transmission rates without significant distress, the following alternatives are provided: Concrete slabs, including garage slabs, should be a minimum of 5 inches thick. • Concrete slab underlayment should consist of a 15-mil vapor retarder, or equivalent, with all laps sealed per the 2010 CBC and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 1745 - Class A criteria, and be installed in accordance with ACI 302.1 R-04 and ASTM E 1643. The 15-mil vapor retarder (ASTM E 1745 - Class A) shall be installed per the recommendations ofthe manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). • Concrete slabs, including the garage areas, should be underlain by 2 inches of clean, washed sand (SE >^ 30) above a 15-mil vapor retarder (ASTM E-1745 - Class A, per Engineering Bulletin 119 [Kanare, 2005]) installed per the recommendations ofthe manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). The manufacturer shall provide instructions for lap sealing, including minimum width of lap, method of sealing, and either supply or specify suitable products for lap sealing (ASTM E 1745), and per code. ACI 302.1 R-04 (2004) states "If a cushion or sand layer is desired between the vapor retarder and the slab, care must be taken to protect the sand layer from taking on additional water from a source such as rain, curing, cutting, or cleaning. Wet cushion or sand layer has been directly linked in the past to significant lengthening of time required for a slab to reach an acceptable level of dryness for floor covering applications." Therefore, additional observation and/ortesting will be Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson street, Carlsbad , October 28,2013 Fil6:e:\wp9\6600\6612a,upg GcoSolIS, IllC. Page 9 necessary for the cushion or sand layer for moisture content, and relatively uniform thicknesses, prior to the placement of concrete. • For very low to low expansive soil conditions, the vapor retarder should be underlain by 2 inches of sand (SE > 30) placed directly on the prepared, moisture conditioned, subgrade and should be sealed to provide a continuous retarder under the entire slab, as discussed above. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede Table 4.3.1 of Chapter 4 of the ACI (2008) for corrosion or other corrosive requirements. Additional concrete mix design recommendations should be provided by the structural consultant and/or waterproofing specialist. Concrete finishing and workablity should be addressed by the structural consultant and a waterproofing specialist. • Where slab water/cement ratios are as indicated herein, and/or admixtures used, the structural consultant should also make changes to the concrete in the grade beams and footings in kind, so that the concrete used in the foundation and slabs are designed and/or treated for more uniform moisture protection. The owner should be specifically advised which areas are suitable for tile flooring, vinyl flooring, or other types of water/vapor-sensitive flooring and which areas are not suitable for these types of flooring applications. In all planned floor areas, flooring shall be installed per the manufactures recommendations. Additional recommendations regarding water or vapor transmission should be provided by the architect/structural engineer/slab or foundation designer and should be consistent with the specified floor coverings indicated by the architect. Regardless ofthe mitigation, some limited moisture/moisture vapor transmission through the slab cannot be entirely precluded and should be anticipated. Construction crews may require special training for installation of certain product(s), as well as concrete finishing techniques. The use of specialized product(s) should be approved by the slab designer and water-proofing consultant. A technical representative of the flooring contractor should review the slab and moisture retarder plans and provide comment prior to the construction of the foundation or improvement. The vapor retarder contractor should have representatives onsite during the initial installation. DRILLED PIER AND GRADE BEAM FOUNDATION RECOMMENDATIONS Due to the proposed location of the swimming pool on the slope face, and in order to minimize potential settlements, the pool foundation should be supported by a drilled, cast-in-place, concrete pier and grade beam system (drilled piers). If desired, the entire Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IllC. Page 10 building foundation may also be supported by drilled piers. Actual pier design should be finalized by the project's structural engineer and the structural capacity ofthe pier(s) used. The structural strength of the piers should be checked by the structural engineer or civil engineer specializing in structural analysis. The grade beam should be at a minimum of 24 inches by 24 inches in cross section and supported by drilled piers, a minimum of 24 inches in diameter which are placed at a maximum spacing of 8 feet on center and a minimum of 3 pier diameters apart and supporting all structural columns. The design ofthe grade beam and piers should be in accordance with the recommendations ofthe project structural engineer, and utilize the following geotechnical parameters. Pier and any grade beam design and construction shall minimally conform to the applicable sections contained in the 2010 CBC (CBSC, 2010). Foundations Design Criteria - Drilled Piers The drilled pier foundation for the pool should gain vertical support from friction and end bearing in the existing terrace deposits underlying the site. Drilled piers for residential foundations are intended to resist vertical and lateral loads due to imposed structural loads and not provide lateral stability/stabilization of slopes. The drilled pier(s) should be at least 24 inches in diameter and should extend at least 10 feet into suitable terrace deposits. The effects of pier groups should be evaluated when the preliminary foundation drawings are made available. Soil parameters to be used in pier and grade beam design are provided below. All the parameters provided are computed based on soil strength only, structural strength of the piers should be checked by the structural engineer or civil engineer specializing in structural analysis. Point of Fixity: Located a distance of 1.5 times the caisson's diameter, below grade. Passive Resistance: Passive earth pressure of 250 psf per foot of depth, to a maximum value of 2,500 psf may be used to determine drilled pier depth and spacing, provided that they meet or exceed the minimum requirements stated above. To determine the total lateral resistance, the contribution of the creep prone zone above the point of fixity, to passive resistance, should be disregarded. No contribution from soil/concrete friction on the bottom of slabs should be included in passive calculations. The upper 12 inches of passive resistance for the drilled piers should be neglected unless confined by slabs or pavement. Additional lateral resistance may be obtained from lateral pile deflection. For a inch lateral pile deflection, a lateral load of 10 percent of vertical capacity can be utilized. A more refined Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28,2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IllC. Page 11 lateral load capacity may be provided when the pier head conditions (fixed, free), layout and elevations are provided by the structural consultant and/or architect on this project. Allowable Axial Capacity: Shaft capacity : 450 psf applied over the surface area of the shaft within bedrock deposits only. Note that some down drag of 250 psf may be realized for settlement of fill soils up to 1 inch. For fill settlements of less than 1 inch, use the full cohesion value of the fill soil and consult with the geotechnical consultant. Tip capacity: 3,500 psf. Assumes clean dense tip condition. Evaluated in the field by the geotechnical consultant. Pile/Fill Settlement: V2 inch between heavy and lighter loaded piles, and should be less than V^t inch for post construction static and dynamic settlement. Outside of the pile supported structures, the potential settlement of any unmitigated fill left in place will likely be more than what was noted previously for remediated fill. CIDH (Drilled Pier) Construction 1. The excavation and installation of the drilled piers should be observed and documented by the project geotechnical engineer to verify the recommended depth. 2. The drilled hole(s) should be cased, specifically below the water table to prevent caving. The bottom of the casing should be at least 4 feet below the top of the concrete as the concrete is poured and the casing is withdrawn. Dewatering may be required for concrete placement if significant seepage or groundwater is encountered during construction. This should be considered during project planning. The bottom ofthe drilled pier should be cleared of any loose or soft soils before concrete placement. 3. The exact depths of pier(s) should be determined during the final precise grading plan review. 4. Proper low slump concrete should be used and should be delivered through tremie pipe. We recommend that concrete be placed through the tremie pipe immediately subsequent to approved excavation and steel placement. Care should be taken to prevent striking the walls of the excavations with the tremie pipe during concrete placement. Vibration of concrete to reduce the potential for segregation should be performed. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad , October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSollS, IllC. Page 12 5. All footing excavations should be observed and approved by the geotechnical consultant prior to placement of concrete forms and reinforcement. 6. Drilled pier steel reinforcement cages should have spacers to allow for a minimum spacing of steel from the side of the pier excavation. All reenforcing bars should be epoxy coated due to the corrosive environment. The need for epoxy coated steel in below grade walls and grade beams should be evaluated by a structural consultant. 7. During pier placement, concrete should not be allowed to free fall more than 5 feet. 8. Concrete and steel used in the foundation should be tested by a qualified materials testing consultant for strength, bar arrangement, and mix design. Corrosion and Concrete Mix Upon completion of grading, laboratory testing should be performed of site materials for corrosion to concrete and corrosion to steel. Additional comments may be obtained from a qualified corrosion engineer at that time. It is assumed by the project architect that all steel will evaluate the need for epoxy-coated, or other, corrosion protection for pier steel reinforcement. ONSITE INFiLTRATION-RUNOFF RETENTION SYSTEMS General Onsite infiltration-runoff retention systems (OIRRS) may be required for Best Management Practices (BMP's) or Low Impact Development (LID) principles for the project. To that end, some guidelines should/must be followed in the planning, design, and construction of such systems. Such facilities, if improperly designed or implemented without consideration of the geotechnical aspects of site conditions, can contribute to flooding, saturation of bearing materials beneath site improvements, slope instability, and possible concentration and contribution of pollutants into the groundwater or storm drain and/or utility trench systems. A key factor in these systems is the infiltration rate (often referred to as the percolation rate) which can be ascribed to, or determined for, the earth materials within which these systems are installed. Additionally, the infiltration rate ofthe designed system (which may include gravel, sand, mulch/topsoii, or other amendments, etc.) will need to be considered. The project infiltration testing is very site specific, any changes to the location of the proposed OIRRS and/or estimated size ofthe OIRRS, may require additional infiltration testing. GSI anticipates that relatively impermeable terrace deposits will occur near the surface at the conclusion of grading. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carisbad . October 28,2013 File:e:\wp9\6600\6612a.upg GCOSoilS, IllC. Page 13 Some of the methods which are utilized for onsite infiltration include percolation basins, dry wells, bio-swale/bio-retention, permeable pavers/pavement, infiltration trenches, filter boxes and subsurface infiltration galleries/chambers. Some of these systems are constructed using native and import soils, perforated piping, and filter fabrics while others employ structural components such as stormwater infiltration chambers and filters/separators. Every site will have characteristics which should lend themselves to one or more of these methods; but, not every site is suitable for OIRRS. In practice, OIRRS are usually initially designed by the project design civil engineer. Selection of methods should include (but should not be limited to) review by licensed professionals including the geotechnical engineer, hydrogeologist, engineering geologist, project civil engineer, landscape architect, environmental professional, and industrial hygienist. Applicable governing agency requirements should be reviewed and included in design considerations. The following geotechnical guidelines should be considered when designing onsite infiltration-runoff retention systems: On a preliminary basis, the onsite soils are considered to fall into Hydrologic Soil Group (HSG) "D" as defined in County of San Diego (2007). It is not good engineering practice to allow water to saturate soils, especially near slopes or improvements; however, the controlling agency/authority is now requiring this for OIRRS purposes on many projects. • Wherever possible, infiltration systems should not be installed within ±50 feet ofthe tops of slopes steeper than 15 percent or within H/3 from the tops of slopes (where H equals the height of slope). Wherever possible, infiltrations systems should not be placed within a distance of H/2 from the toes of slopes (where H equals the height of slope). • Impermeable liners and subdrains should be used along the bottom of bioretention swales/basins located within the influence of slopes such as exists onsite. Due to the proximity of the planned bioretention basin to an adjacent, offsite slope and retaining wall, the basin should be provided with an impermeable liner around the entire basin. The 30 mil thick PVC liner should meet the following specifications: specific gravity (ASTM D792); 120 (min.), tensile strength (ASTM D 882); 73 (Ib/in-width, min.), elongation at break (ASTM D D882): 380 (%min.), modulus (ASTM D 882): 30 (Ib/in-width, min.), tear resistance (ASTM D1004): 30 (lb/in, min.). The landscape architect should be notified of the location of the proposed OIRRS. If landscaping is proposed within the OIRRS, consideration should be given to the type of vegetation chosen and their potential effect upon subsurface improvements (i.e., some trees/shrubs will have an effect on subsurface improvements with their Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad , October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IHC. Page 14 extensive root systems). Over-watering landscape areas above, or adjacent to, the proposed OIRRS could adversely affect performance ofthe system. Areas adjacent to, or within, the OIRRS that are subject to inundation should be properly protected against scouring, undermining, and erosion, in accordance with the recommendations of the design engineer. If subsurface infiltration galleries/chambers are proposed, the appropriate size, depth interval, and ultimate placement ofthe detention/infiltration system should be evaluated by the design engineer, and be of sufficient width/depth to achieve optimum performance, based on the infiltration rates provided. In addition, proper debris filter systems will need to be utilized for the infiltration galleries/chambers. Debris filter systems will need to be self cleaning and periodically and regularly maintained on a regular basis. Provisions for the regular and periodic maintenance of any debris filter system is recommended and this condition should be disclosed to all interested/affected parties. Infiltrations systems should not be installed within ±8 feet of building foundations utility trenches, and walls, or a 1:1 (h:v) slope (down and away) from the bottom elements of these improvements. Alternatively, deepened foundations and/or pile/pier supported improvements may be used. Infiltrations systems should not be installed adjacentto pavement and/or hardscape improvements. Alternatively, deepened/thickened edges and curbs and/or impermeable liners may be utilized in areas adjoining the OIRRS. Appropriate setbacks from the bio retention area should be provided for settlement sensitive improvements. As with any OIRRS, localized ponding and groundwater seepage should be anticipated. The potential for seepage and/or perched groundwater to occur after site development should be disclosed to all interested/affected parties. Installation of infiltrations systems should avoid expansive soils (E.I. >51) or soils with a relatively high plasticity index (P.I. > 20). Where permeable pavements are planned as part of the system, the site Traffic Index (T.I.) Should be less than 25,000 Average Daily Traffic (ADT), as recommended in Allen, et al. (2011). Infiltration systems should be designed using a suitable factor of safety (FOS) to account for uncertainties in the known infiltration rates (as generally required by the controlling authorities), and reduction in performance overtime. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad . October 28, 2013 File:e:\wp9\6600\6612a.upg GCOSOllS, IllC. Page 15 As with any OIRRS, proper care will need to be provided. Best management practices should be followed at all times, especially during inclement weather. Provisions for the management of any siltation, debris within the OIRRS, and/or overgrown vegetation (including root systems) should be considered. An appropriate inspection schedule will need to adopted and provided to all interested/affected parties. Any designed system will require regular and periodic maintenance, which may include rehabilitation and/or complete replacement ofthe filter media (e.g., sand, gravel, filter fabrics, topsoils, mulch, etc.) or other components utilized in construction, so that the design life exceeds 15 years. Due to the potential for piping and adverse seepage conditions, a burrowing rodent control program should also be implemented onsite. All or portions of these systems may be considered attractive nuisances. Thus, consideration ofthe effects of, or potential for, vandalism should be addressed. Newly established vegetation/landscaping (including phreatophytes) may have root systems that will influence the performance of the OIRRS or nearby LID systems. The potential for surface flooding, in the case of system blockage, should be evaluated by the design engineer. Any proposed utility backfill materials (i.e., inlet/outlet piping and/or other subsurface utilities) located within or near the proposed area of the OIRRS may become saturated. This is due to the potential for piping, water migration, and/or seepage along the utility trench line backfill. If utility trenches cross and/or are proposed near the OIRRS, cut-off walls or other water barriers will need to be installed to mitigate the potential for piping and excess water entering the utility backfill materials. Planned or existing utilities may also be subject to piping of fines into open-graded gravel backfill layers unless separated from overlying or adjoining OIRRS by geotextiles and/or slurry backfill. The use of OIRRS above existing utilities that might degrade/corrode with the introduction of water/seepage should be avoided. A vector control program may be necessary as stagnant water contained in OIRRS may attract mammals, birds, and insects that carry pathogens. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28, 2013 File:e;\wp9\6600\6612a.upg GCOSollS, IHC. Page 16 DEVELOPMENT CRITERIA Drainage Adequate surface drainage is a very important factor in reducing the likelihood of adverse performance of foundations and hardscape. Surface drainage should be sufficient to mitigate ponding of water anywhere on the property, and especially near the structure. 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 the property should be provided and maintained at all times. Surface water should be directed away from foundations, and not allowed to pond and/or seep into the ground. In general, site drainage should conform to Section 1804.3 ofthe 2010 CBC. Consideration should be given to avoiding construction of planters adjacent to structures (i.e., buildings, pools, spas, etc.). Building 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 the structure 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 Onsite earth materials have a moderate to high erosion potential. Consideration should be given to providing hay bales and silt fences forthe temporary control of surface water, from a geotechnical viewpoint. Landscape Maintenance Water has been shown to weaken the inherent strength of all earth materials. 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 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. If 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. 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 Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad . October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSoils, IHC. Page 17 of a sparse plant cover. Utilizing plants other than those recommended above will increase the potential for perched water, staining, mold, etc., to develop. 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. A rodent control program to prevent burrowing should be implemented. 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 other non-erosive devices (e.g., paved swales or ditches; below grade, solid tight-lined PVC pipes; etc.), that will carry the water away from the house, to an appropriate outlet, in accordance with the recommendations of the design civil engineer. 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 If in the future, any additional improvements (e.g., pools, spas, etc.) are planned for the site, recommendations concerning the geological or geotechnical aspects of design and construction of said improvements could be provided upon request. Pools and/or spas should not be constructed without specific design and construction recommendations from GSI, and this construction recommendation should be provided to all interested/affected parties. This office should be notified in advance of any fill placement, grading ofthe site, or trench backfilling after rough grading has been completed. This includes any grading, utility trench and retaining wall backfills, flatwork, etc. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad ^ October 28,2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IllC. Page 18 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, driveway approaches, driveways, parking areas, and utility trench and retaining wall backfills. 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 evaluate that the excavations have been 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. 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/Temporary Construction Backcuts Considering the nature ofthe onsite earth materials, it should be anticipated that caving or sloughing could be a factor in subsurface excavations and trenching. Shoring or excavating the trench walls/backcuts at the angle of repose (typically 25 to 45 degrees [except as specifically superceded within the text of this report]), should be anticipated. All excavations should be observed by an engineering geologist or soil engineer from GSI, prior to workers entering the excavation or trench, and minimally conform to CAL-OSHA, state, and local safety codes. Should adverse conditions exist, appropriate recommendations would be offered at that time. The above recommendations should be provided to any contractors and/or subcontractors, or homeowner(s), etc., that may perform such work. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28, 2013 File:e:\wp9\6600\6612a.upg GCOSoilS, IllC. Page 19 utility Trench Backfill 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 evaluate 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 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 evaluate the desired results. 3. All trench excavations should conform to CAL-OSHA, state, 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 ofthe 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 excavation. During placement of subdrains 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 retarders (i.e., visqueen, etc.). Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson street, Carlsbad , October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IllC. Page 20 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. During slope construction/repair. When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. A report of geotechnical observation and testing should be provided at the conclusion of each of the above stages, in order to provide concise and clear documentation of site work, and/or to comply with code requirements. OTHER DESIGN PROFESSIONALS/CONSULTANTS The design civil engineer, structural engineer, post-tension designer, architect, landscape architect, wall designer, etc., should review the recommendations provided herein, incorporate those recommendations into all their respective plans, and by explicit reference, make this report part of their project plans. This report presents minimum design criteria for the design of slabs, foundations and other elements possibly applicable to the project. These criteria should not be considered as substitutes for actual designs by the structural engineer/designer. Please note that the recommendations contained herein are not intended to preclude the transmission of water or vapor through the slab or foundation. The structural engineer/foundation and/or slab designer should provide recommendations to not allow water or vapor to enter into the structure so as to cause damage to another building component, or so as to limit the installation of the type of flooring materials typically used for the particular application. The structural engineer/designer should analyze actual soil-structure interaction and consider, as needed, bearing, expansive soil influence, and strength, stiffness and deflections in the various slab, foundation, and other elements in order to develop appropriate, design-specific details. As conditions dictate, it is possible that other influences will also have to be considered. The structural engineer/designer should consider all applicable codes and authoritative sources where needed. If analyses by the structural engineer/designer result in less critical details than are provided herein as minimums, the minimums presented herein should be adopted. It is considered likely that some, more restrictive details will be required. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad _ October 28, 2013 File:e:\wp9\6600\6612a.upg GcoSoilS, IllC. Page 21 If the structural engineer/designer has any questions or requires further assistance, they should not hesitate to call or otherwise transmit their requests to GSI. In order to mitigate potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, thatthe proposed foundations and/or improvements can tolerate the amount of differential settlement and/or expansion characteristics and other design criteria specified herein. PLAN REVIEW Final project plans (grading, precise grading, foundation, retaining wall, landscaping, etc.), should be reviewed by this office prior to construction, so that construction is in accordance with the conclusions and recommendations of this report. Based on our review, supplemental recommendations and/or further geotechnical studies may be warranted. LIMITATIONS The materials encountered on the project site and utilized for our analysis are believed representative ofthe 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, either express or implied, is given. 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. Thus, this report brings to completion our scope of services for this portion ofthe project. All samples will be disposed of after 30 days, unless specifically requested by the client, in writing. Ms. Veronica De Anda W.O. 6612-A-SC 2425 Jefferson Street, Carlsbad , October 28, 2013 File:e:\wp9\6600\6612a.upg GCOSoilS, IllC. Page 22 The opportunity to be of service is greatly appreciated. If you have any questions concerning this report, or if we may be of further assistance, please do not hesitate to contact any of the undersigned. Respectfully submitted^xO GeoSoils, Inc. / 3L§' \ Cerii Robert G. Crisman Engineering Geologist, CE RGC/DWS/JPF/jh Attachment: Appendix - References Distribution: (4) Addressee //(3^3'rr- tit "\ln David W. Skelly cf::;:^^^ Civil Engineer, RCE 4785^;^:;^^^ Ms. Veronica De Anda 2425 Jefferson Street, Carlsbad File:e:\wp9\6600\6612a.upg GeoSoils, Inc. W.O. 6612-A-SC October 28, 2013 Page 23 APPENDIX REFERENCES Allen, v., Connerton, A., and Carlson, C, 2011, Introduction to Infiltration Best Management Practices (BMP), Contech Construction Products, Inc., Professional Development Series, dated December. American Concrete Institute, 2004, Guide for concrete floor and slab construction: reported by ACI Committee 302; Designation ACI 302.1 R-04, dated March 23. American Concrete Institute Committee 318, 2008, Building code requirements for structural concrete (ACI 318-08) and commentary, dated January. American Concrete Institute Committee 360, 2006, Design of slabs-on-ground (ACI 360R-06). American Concrete Institute Committee 302, 2004, Guide for concrete floor and slab construction, ACI 302.1 R-04, dated June. American Concrete Institute Committee on Responsibility in Concrete Construction, 1995, Guidelines for authorities and responsibilities in concrete design and construction in Concrete International, vol 17, No. 9, dated September. American Society for Testing and Materials, 2004, Standard specification for water vapor retarders used in contact with soil or granular fill under concrete slabs. , 1998, Standard practice for installation of water vapor retarder used in contact with earth or granular fill under concrete slabs. Designation: E 1643-98 (Re-approved 2005). , 1997, Standard specification for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs. Designation: E 1745-97 (Reproved 2004). Beery Group Architecture, 2013, Architectural plans for: the De Anda residence. Job No. 1309, dated August 19. California Building Standards Commission, 2010, California Building Code, California Code of Regulations, Title 24, Part 2, Volume 2 of 2, Based on the 2009 International Building Code, 2010 California Historical Building Code, Title 24, Part 8; 2010 California Existing Building Code, Title 24, Part 10. GeoSoils, Inc. Cao, T., Bryant, W.A., Rowshandel, B., Branum, D., and wiilis, C.J., 2003, The revised 2002 California probalistic seismic hazard maps, dated June, http://www.conversation.ca.gov/cqs/rghm/psha/fault parameters/pdf/documents /2002_ca_hazardmaps.pdf County of San Diego, Department of Planning and Land Use, 2007, Low impact development (LID) handbook, stormwater management strategies, dated December 31. GeoSoils, Inc., 2008, Updated preliminary geotechnical evaluation, APN 155-140-41, Carlsbad, San Diego County, California, W.O. 5763-A-SC, dated October 15. , 2003, Update preliminary geotechnical evaluation, APNs 155-140-37 and 155-140-38, City of Carlsbad, San Diego County, California, W.O. 3213-A-SC, dated September 18. , 1993, Preliminary geotechnical evaluation. Parcel 155-140-09, Carlsbad, California, W.O. 1624-SD, dated November 2. International Conference of Building Officials, 1998, Maps of known active fault near-source zones in California and adjacent portions of Nevada. Kanare, H., 2005, Concrete floors and moisture, Portland Cement Association, Skokie, Illinois. Sampo Enginering, Inc, 2013, Preliminary grading plan for: De Anda residence, APN 155- 14-41 Job No. 13-109, dated August 14. State of California, 2013, Civil Code, Title 7, Division 2, Section 895, et seq. United States Geological Survey, 2012, 2008 Earthquake Hazards Program, 2008 interactive deaggregations (Beta), Earthquake Hazards Program; http://eqint.cr.usgs.qov/deaqgint/2008/. , 2011, Seismic hazard curves and uniform hazard response spectra, NEHRP Option, Version 5.1.0, dated February 10. , 2007, Working Group on California Earthquake Probabilities, 2008, The uniform California earthquake rupture forecast, version 2 (UCERF2); U.S. Geological Sun/ey Open-File Report 2007-1437, and California Geological Survey Special Report 203, http://pubs.usgs.qov/of/2007/1437/. Ms. Veronica De Anda _ Appendix File:e:\wp9\6600\6612a.upg GcoSoilS, IttC. Page 2