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HomeMy WebLinkAboutCDP 2018-0040; RAUM RESIDENCE; UPDATED GEOTECHNICAL EVALUATION; 2010-06-16_ GEOTECHNICAL UPDATE, PARCEL 1 OF PARCEL MAP 19411, APN 215-070-39 . CARLSBAD, SAN DIEGO COUNTY, CALIFORNIA · FOR · A&E CONSTRUCTION SERVICES 538 FRONT STREET EL CAJON, CALIFORNIA 92020 W.O. 6087,-A-SC JUNE 16, 2010 · ~PR O 1 20'9 I • , ' \,ic.NT ND -·· ENG1Nb.~R\N.G Geotechnical • Geologic • Coastal • Environmental 5741 Palmer Way • Carlsbad, California 92010 • (760) 438-3155 • FAX (760) 931-0915 • www.geosoilsinc.com A&E Construction Services 538 Front Street El Cajon California 92020 Attention: Mr. Joe Esposito June 16, 201 0 W.O. 6087-A-SC Subject: Geotechnical Update, Parcel 1 of Parcel Map 19411, APN 135-030-55, Carlsbad, San Diego County, California Dear Mr. Esposito: In accordance with a request and authorization, GeoSoils, Inc. (GSI), has prepared this report for the purpose of updating our previous referenced reports (see Appendix A), in light of current standards of practice. This update is based on visual observations made during a site reconnaissance, performed on June 15, 2010, a review of the conceptual plans provided by the client, and GSl's previous reports (see Appendix A). Recommendations contained in the previous reports, which are not specifically superceded by this review, should be properly incorporated into the design and construction phases of site development. SITE CONDITIONS/PROPOSED DEVELOPMENT The site consists of an irregular-shaped property, located on the northwest corner lot of the proposed "Lynn Minor Subdivision," west of Black Rail Road, in Carlsbad, San Diego County, California. Based on our previous reports (see Appendix A), the site was rough graded sometime around January 13, 2004, and was generally completed on January 29, 2004. It is our understanding that proposed construction will consist of a lot split and the construction of two, two-story single-family residences on the lots. Cut and fill grading techniques would be utilized to create design grades for the proposed split-level single- family residential structures, with slab-on-grade floors and continuous footings, utilizing wood-frame and/or masonry block construction. Building loads are assumed to be typical for this type of relatively light construction. The need for import soils is unknown. Sewage disposal for the site is anticipated to be tied into the regional system. PLAN REVIEW A review of the ±20-scale conceptual grading plan (unknown author and date), it appears thatthe lower levels of both proposed residences will have cut-fill transitions. The northerly residence pad grade for the basement is shown as 361 feet Mean Sea Level (MSL), which indicates on the west side, there will be about 3 to 4 feet of engineered fill below this elevation; in contrast on the east side of the basement, there will be some cut and/or up to about a foot of engineered fill below this elevation, which would result in a non-uniform subgrade. Additionally, retaining walls supporting outside improvements as well as the superjacent split levels are proposed. Thus, the two upper pads on the proposed northerly residence will be fill, also indicating non-uniformity of subgrade for the foundations, walls, and slabs-on-grade of the structure as a whole. The sou~herly proposed residence will have a cut-fill transition through a portion of the lower level, with most of the lower level proposed as cut. Similar to above, retaining walls supporting outside improvements as well as the superjacent split level are proposed. Again, the two upper pad on the proposed southerly residence will be fill, also indicating non-uniformity of subgrade for the foundations, walls, and slabs-on-grade of the structure as a whole. SEISMIC SHAKING PARAMETERS Based on the site conditions, the table below summarizes the site-specific design criteria obtained from the 2007 California Building Code ([2007 CBC], California Building Standards Commission [CBSC], 2007), Based on the 2006 International Building Code (IBC), Chapter 16 Structural Design, Section 1613. We used the computer program Seismic Hazard Curves and Uniform Hazard Response Spectra, provided by the United States Geological Survey (USGS, 2009). The short spectral response uses a period of 0.2 seconds. Site Class Spectral Response -(0.2 sec), S5 Spectral Response -(1 sec), S1 Site Coefficient, Fa Site Coefficient, F v Maximum Considered Earthquake Spectral Response Acceleration (0.2 sec), SMs Maximum Considered Earthquake Spectral Response Acceleration (1 sec), SM1 A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. D 1.49g 0.56g 1.0 1.5 1.49g 0.84g Table 1613.5.2 Figure 1613.5(3) Figure 1613.5(4) Table 1613.5.3(1) Table 1613.5.3(2) Section 1613.5.3 (Eqn 16-37) Section 1613.5.3 (Eqn 16-38) W.O. 6087-A-SC June 16, 201 O Page2 5% Damped Design Spectral Response Acceleration (0.2 sec}, S08 5% Damped Design Spectral Response Acceleration (1 sec}, S01 0.99g 0.56g Section 1613.5.4 (Eqn 16-39} Section 1613.5.4 · (Eqn 16-40} 'L~lii!l.i!lwJ"l,•«'r.iij/.,'si!'-i;ir,'\lt,!ff.1~X'fjl'~~j)1!ii'llll'ljje~•r.,:e..,,,,.,,,,., •• ~=,~•<'i"§,""""'""1•w,,•:r.••i:::t:11""·,·,,,,~.••;•.,m,, ....... ,,"'"'."G'"•>"'!iiii~""·==""'-''"""'f:1,:j!i;,:/,,fJi!i'l:i/j!li!i!'IW~•!!'io'ai!,11il,~~s:jj;l''.;!:"'rn~':lli<M·\j;,11!i'I!':(/' .~mii~,s,J~ti1..'1Mstrc!fl~!Jll.~.iate:ift~'i).\ff~liii~Ji!lij1LGENE.8'/f..li.\SE SMl~1Q.E$1G.Nl,RA~JV1.EfJEBS~r.t!111.il~iW,1t\iliit.~~.;i,w~..:fm;ll:I~,~~~ Distance to Seismic Source (Rose Canyon fault} 5.6 mi. (9.0 km} Upper Bound Earthquake (Rose Canyon fault} Mw 6.9* Probabilistic Horizontal Site Acceleration ([PHSA] 10% probability of exceedance in 50 years} I* International Conference of Building Officials (ICBO, 1998) 0.19g 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. PREVIOUS LABORATORY TESTING Previous laboratory test results by GSI which are relevant to the currently proposed development are summarized below: Expansion Index As indicated in GSI (2004d), the expansion index of a representative sample of soil exposed near finish grade is less than 20. According to Table 1 BA-I-B of the 2001 CBC (International Conference of Building Officials [ICBO], 2001), the expansion potential of the tested soil is classified as very low expansive. This definition is not in the 2007 CBC, however is utilized herein as a classification tool. Maximum Density Testing As indicated in GSI (2004d), the laboratory maximum dry density and optimum moisture content for the major soil type encountered during grading were determined according to test method ASTM D 1557. The following table presents the results: A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page3 A-Orange Brown, SILTY SAND 131.0 9.0 B -Gra Brown SIL TY SAND Im ort 137.0 9.0 Saturated Resistivity, pH, and Soluble Salt A representative sample of the site materials has been previously analyzed for corrosion, soluble sulfates, and chlorides (GSI, 2002a). Laboratory testing indicates that site soils generally have a negligible sulfate content (54 mg/kg) and a non-detectible chloride content. Per Table 4.2.1 of ACI 318-08 (per the 2007 CBC [CBSC, 20071), the site soils are not applicable to special concrete design for soluble salts. Corrosion testing (pH/saturated resistivity) indicates that the site soils are slightly acid (pH = 6.5) with respect to soil acidity/alkalinity and are moderately corrosive to exposed ferrous metals when saturated (saturated resistivity = 2,900 ohm-cm [California Highway Design Manual, 20061). Alternative testing methods and additional comments should be obtained from a qualified corrosion engineer with regard to foundations, piping, etc. PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS Geotechnically, the subject site is in essentially the same condition as it appeared during the preparation of our previous report (GSI, 2004d), with the exception that the surficial fill is weathered, and somewhat dry to loose, as a result. Based upon our review of the current conceptual plan provided by you, the previous GSI reports (Appendix A), and geologic and engineering analyses, the proposed development of this site is geotechnically feasible, provided our recommendations are properly implemented. It is our understanding that the proposed lot split will require regrading the existing lot to proposed grades. Therefore, the referenced geotechnical reports are generally considered relevant and applicable to the proposed construction. Recommendations contained in the previous reports (see Appendix A), which are not specifically superceded by this review, should be properly incorporated into the design and construction phases of site development. It should be noted, that the 2007 California Building Code ([2007 CBC] California Building Standards Commission [CBSC], 2007) indicates that removals of unsuitable soils be performed across all areas under the purview of a grading permit, not just within the influence of the residential structure. Relatively deep removals may also necessitate a special zone of consideration, on perimeter, confining areas, such that this potential zone is approximately equal to the depth of removals, if removals cannot be performed offsite. Thus, any settlement-sensitive improvements (perimeter walls, curbs, flatwork, etc.), constructed within this perimeter zone may require deepened foundations, reinforcement, A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Inc. W.O. 6087-A-SC June 16, 201 O Page4 etc., or will retain some potential for settlement and associated distress, if not properly mitigated during grading. The recommendations in the following sections should be properly incorporated into project planning, design and construction. Earthwork Recommendations General Remedial earthwork will be necessary for the proper support of planned fill and proposed settlement-sensitive improvements. All grading should conform to the guidelines presented in Appendix J of the 2007 CBC (CBSC, 2007), the requirements of the City of Carlsbad, and the Grading Guidelines presented in Appendix 8 of this report (except where specifically superceded in the text of this report). In case of conflict, the more onerous code or recommendations should govern. Prior to grading, a GSI representative should be present at the pre-construction meeting to provide additional grading guidelines, if needed, and to review the earthwork schedule. During earthwork construction, all site preparation and the general grading procedures of the 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 the responsibility of the onsite general contractor and individual subcontractors to provide a safe working environment. GSI does not consult in the area of safety engineering. Existing Vegetation and Debris All existing vegetation and debris (concrete, degraded storm water BMPs, etc.) within the influence of proposed development should be removed and properly disposed. Existing Building Pad and Private Drive Owing to almost six years of remaining fallow, the upper 1 foot of the existing, weathered fill soils exposed at the surface of the building pad and the private drive shouid be removed, moisture-conditioned to at least the soil's optimum moisture content, and then be mechanically compacted to at least 90 percent of the laboratory standard (ASTM D 1557), to 5 feet outside of any settlement-sensitive improvements. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O · Page 5 Existing Fill Slopes Sparse to locally abundant rodent burrows were observed on the fill slope descending from the building pad. Prior to remedial earthwork, a contractor specializing in rodent abatement should observe the site conditions and provide recommendations for mitigation as necessary. Following rodent abatement, the existing fill materials on the slope surface should be scarified 6 to 12 inches, moisture conditioned to the soil's optimum moisture content, and then be recompacted to at least 90 percent of the laboratory standard. The slope surface should be reconstructed to its original planned gradient of 2:1 (h:v). In addition, the observed scouring at the toe of the south-facing fill slope should be scarified 6 to 12 inches, moisture conditioned to at least the soil's optimum moisture content, and then returned to it original graded condition with compacted fill materials. Rodent control will need to be maintained over the life of the project. New Fill Slope (South Portion of Turf Area) Based on the remedial earthwork documented in GSI (2004d), generally, cut grading operations took place and limited fill was placed along the proposed road. Therefore, remedial removal and recompaction of unsuitable soils (i.e., undocumented fill, topsoil/colluvium, weathered terrace deposits/fill) in this area will be necessary for proper support. Based on a review of GSI (2002b) remedial removal excavations may be on the order of 3 or 4 feet below the existing grade. However, locally deeper removal excavations may be necessary to remove unsuitable soils, and should be anticipated during grading. Remedial removal excavations should be completed below a 1 : 1 (h:v) projection down from the toe of the proposed slope. A minimum equipment width keyway should then be established by providing at least 2 feet of embedment into competent terrace deposits at the toe of the keyway and sloping the bottom of the keyway at least 2 percent from toe to heel. Prior to placing fill in the keyway, the bottom should be scarified at least 6 inches, moisture conditioned to the soil's optimum moisture content, and then be recompacted to at least 90 percent of the laboratory standard (ASTM D 1557). Fill should then be placed in thin lifts, moisture conditioned to at least optimum moisture content and then be mechanically compacted to at least 90 percent of the laboratory standard (ASTM D 1557). During fill placement for construction of the new slope, unsuitable soils should be benched to expose competent terrace deposits or unweathered fill. OVEREXCAVATION/NON-UNIFORM SUBGRADE In order to provide for the uniform support of the planned improvements, a minimum 3-foot thick fill blanket is recommended for the graded pads. Any cut portion of the pads for the residences should be overexcavated a minimum 3 feet below finish pad grade and at least 5 feet outside of the building footprint. Areas with planned fills less than 3 feet should be A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page6 overexcavated in order to provide the minimum fill thickness. Based on GSl's review of our prior report (GSI, 2004d), the proposed lower floor levels will need to be overexcavated a minimum of 3 feet below proposed grade for both planned residences, if remedial removals do not penetrate to these elevations. Fill thickness should not exceed a ratio of 3: 1 (maximum to minimum) across the building areas. The intent of this recommendations is to have a minimum fill thickness of at least 2 feet below all footings. COMPACTION STANDARDS In light of the sandy onsite soils, with low fines content (cohesion of less than 250 pounds per square foot [psf] on average, and proposed buildings split level construction, it is recommended that fill or backfill placed within the building footprint, or within 5 feet from the buildings or retaining walls, that the compaction standard should be increased to 95 percent of ASTM D-1557, at or above optimum moisture content, to mitigate static and seismic ·differential settlement. This condition should be readily achievable owing to the sandy materials onsite. PRELIMINARY FOUNDATION RECOMMENDATIONS 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 supersede design by the project structural engineer. Upon request, GSI could provide additional input/consultation regarding soil parameters, as they relate to foundation design. The following preliminary foundation design and construction recommendations are based on laboratory testing and engineering analysis of o_nsite earth materials by GSI. Previous laboratory testing (GSI, 2004d) indicates that the expansion potential of near-finish grade soils are generally in the very low (E.I. Oto 20 range) range according to Table 18-1-8 of the 2001 CBC (ICBO, 2001) with a Pl less than 15. Therefore, foundations do not need to comply with Section 1805A.8 of the 2007 CBC (CBSC, 2007) to mitigate expansive soil effects. However, due to regionally pervasive paleoliquefaction features, GSI (2002b) recommended the use of post-tensioned slabs for support of any residential structure constructed on these lots. The recommendations provided herein consider that condition. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 O Page7 POST-TENSIONED SLAB AND FOUNDATIONS General 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. The following recommendations for the design of post-tensioned slabs have been prepared in general compliance with the requirements of the recent Post Tensioning lnstitute's (PTl's) publication titled "Design of Post -Tensioned Slabs on Ground, Third Edition" together with it's subsequent addendums. From a soil expansion/shrinkage standpoint, a common contributing factor to distress of structures using post-tensioned slabs is a "dishing" or "arching" of the slabs. This is caused by the fluctuation of moisture content in the soils below the perimeter of the slab primarily due to climatic and seasonal changes, and the presence of expansive soils. When the outside soil environment surrounding the slab has a higher moisture content than the area beneath the slab, moisture tends to migrate underneath the slab edges to a distance beyond the slab edges known as a moisture variation distance, and cause the slab edges to lift. Conversely, when the outside soil environment is drier, the moisture regime is reversed and the soils underneath the slab edges lose their moisture and shrink. This process leads to dropping of the slab at the edges, which leads to what is commonly referred to as the center lift condition. Therefore, post-tensioned slabs should have sufficient stiffness and rigidity to resist excessive bending due to non-uniform swell and shrinkage of subgrade soils, particularly within the moisture variation distance, near the slab edges. Design 1. An allowable bearing value of 2,000 psf may be used for design of footings which maintain a minimum width of 12 inches (continuous) and 24 inches square (isolated), and a minimum depth of embedment at least 12 inches into properly engineered fill. This embedment does not include the concrete floor slab or slab underlayment inside the building nor the upper few inches of landscape soil on the exterior of the building. The bearing value may be increased by one-third for seismic or other transient loads. This value may also be increased by 20 percent for each additional 12 inches in depth to a maximum of 2,500 psf for foundations embedded into engineered fill. No increase in bearing value for increased footing width is recommended. 2. For lateral sliding resistance, a 0.25 coefficient of friction may be utilized for a concrete to soil contact when multiplied by the dead load for foundations embedded in fill. Foundations embedded into formation, a value of 0.4 may be used. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeaSails, lne. W.O. 6087-A-SC June 16, 201 O Page8 3. Passive earth pressure may be computed as an equivalent fluid having a density of 200 pcf with a maximum earth pressure of 2,000 psf. 4. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 5. All footings should maintain a minimum 7-foot horizontal distance between the base of the footing and any adjacent descending slope, and minimally comply with the guidelines depicted on Figure 1805A.3.1 of the 2007 CBC (CBSC, 2007). Stiffened Slabs For a typical slab designed with interior ribs, or stiffeners, the slab should be at least 5 inches thick for soils with a very low expansion potential. The ribs should be provided in both transverse and longitudinal directions. The interior rib spacing and depth should be provided by the project structural engineer responsible for the design of the post-tensioned slabs. The perimeter beams, however, should be embedded at least 12 inches for soils with a very low expansion potential. The embedment depth should be measured downward from the lowest adjacent grade surface to the bottom of the beam. Uniform Thickness Foundations (UTF) The foundation slab thickness should be designed· by the project structural engineer. However, if a UTF foundation is used, a minimum thickness of 6 inches should be incorporated into the foundation. Pre-Soaking Due to the very low expansion potential of the tested onsite soils, no specific pre-soaking program appears warranted. However, for very low expansive soils, the moisture content of the subgrade soils should be 1 to 2 percentage points above the optimum moisture content to a depth of 12 inches below grade, prior to pouring concrete. Soil Support Parameters The recommendations for soil support parameters have been provided based on typical soil index properties for soils ranging from very low to low in expansion potential. The soil index properties are typically the upper bound values based on our experience and practice in the southern California area, and are provided in the table below: A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 O Page9 Suction Compression Index-Swell 5.0feet Suction Compression Index-Shrink 3.5 feet Upper Bound Liquid Limit (LL) 35 Upper Bound Plasticity Index (Pl) 20 Upper Bound Percent Fines (-#200) 30 Upper Bound Percent Clay 15 Soil Fabric Factor (Ff) 1.0 Modified Unsaturated Diffusion Coefficient -a' Swell (Edge Lift) 5.00 E-03 Modified Unsaturated Diffusion Coefficient-a' Shrink (Center Lift) 5.02 E-03 Equilibrium Suction pF 3.9 Thornthwaite Index Oto -20 Based on the above, the recommended preliminary soil support parameters are tabulated below: em center lift 9.0feet em edge lift 5.2feet y m center lift 0.5 inch 0.6 inch The coefficients are considered minimums and may not be adequate to represent worst case conditions such as adverse drainage and/or improper landscaping and maintenance. The above parameters are applicable provided structures have positive drainage that is maintained away from structures. In addition no trees with significant root systems are planted within 15 feet of the perimeter foundations. Therefore, it is important that information regarding drainage, site maintenance, trees, settlements, and effects of expansive soils be passed on to future owners. The values tabulated above may not be appropriate to account for possible differential settlement of the slab due to other factors, such as excessive settlements. If a stiffer slab is desired, higher values of Ym may be recommended. A&E Construction APN 215-070-39, Qarlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 O Page 10 Settlement In addition to designing slab systems (post-tension or other) for the soil conditions, described herein, the estimated settlement and angular distortion values that an individual structure could be subject to should be evaluated by a structural engineer as differential settlement of 1 inch over 40 feet. Footing Setbacks All footings should maintain a minimum 7-foot horizontal setback from the base of the footing to any descending slope and minimally comply with the guidelines depicted on Figure 1805A.3.1 of the 2007 CBC (CBSC, 2007). The setback distar.ice is measured from the footing face at the bearing elevation. Footings constructed on the existing fill slope should be deepened below the creep zone (see the "Top-of-Slope Walls/Fences/Improvements" section of this report). Footings adjacentto unlined drainage .swales should be deepened to a minimum of 6 inches below the invert of the adjacent unlined swale. Footings for structures adjacent to retaining walls should be deepened so as to extend below a 1 :1 projection from the heel of the wall. Alternatively, walls may be designed to accommodate structural loads from buildings or appurtenances. Alternative Foundation Design for Mitigation of Paleoliquefaction Features As an alternative to post-tension foundations, the structural engineer may design a conventional-type foundation equipped with interconnected stiffening beams. The structural engineer should design the thickness of the concrete slab and reinforcing bar size and spacing to accommodate the edge and center distortions listed above. Perimeter footings should be at least 15 inches wide and be embedded a minimum of 18 inches below the lowest adjacent grade into engineered fill for two-story floor loads. Isolated pad footing should be connected in at least one direction, and be at least 24 inches square, and embedded at least 24 inches below the lowest adjacent grade into engineered fill. The minimum concrete slab thickness should be 5 inches. SOIL MOISTURE CONSIDERATIONS GSI has evaluated the potential for vapor or water transmission through the slabs, in light of typical residential floor coverings and improvements. Please note that typical slab moisture emission rates range from about 2 to 27 lbs/24 hours/1,000 square feet from a normal slab (Kanare, 2005), while typical floor covering manufacturers recommend about 3 lbs/24 hours as an upper limit. Thus, the client will need to evaluate the following in light of a cost v. benefit analysis, along with performance limitations. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 11 Considering the anticipated typical water vapor transmission rates, floor coverings and improvements (to be chosen by the client) that can tolerate those rates without distress, the following alternatives are provided: 1 . Concrete slabs should be a minimum of 5 inches thick. 2. Concrete slab underlayment should consist of a 10-mil to 15-mil vapor retarder, or equivalent, with all laps sealed per the 2007 CBC (CBSC, 2007} and the manufacturer's recommendation. The vapor retarder should comply with the ASTM E 17 45 -Class A or B criteria, and be installed in accordance with ACI 302.1 R-04 and ASTM E 1643. The 10-to 15-mil vapor retarder (ASTM E-17 45 - Class A) shall be installed per the recommendations of the manufacturer, including all penetrations (i.e., pipe, ducting, rebar, etc.). 3. Slab underlayment should consist of 2 inches of washed sand placed above a vapor retarder consisting of 10-to 15-mil polyvinyl chloride, or equivalent, with all laps sealed per the 2007 CBC (CBSC, 2007). The vapor retarder shall be underlain by 4 inches of. pea gravel (½ to ¾ subangular to angular clean crushed rock, 0 to 5 percent fines) placed directly on properly compacted subgrade soils, and should be sealed to provide a continuous water-resistant barrier under the entire slab, as discussed above. All slabs should be additionally sealed with suitable slab sealant. If the subgrade soils have a sand equivalent (SE) greater than 30, the 4-inch pea gravel layer may be omitted. 4. Concrete should have a maximum water/cement ratio of 0.50. This does not supercede the 2007 CBC (CBSC, 2007) 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. 5. Where slab water/cement ratios are as indicated above, 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. 6. Owners(s) and all interested/affected parties should be specifically advised which areas are suitable for tile flooring, wood flooring, or other types of water/vapor-sensitive flooring and which are not suitable. In all planned floor areas, flooring shall be installed per the manufactures recommendations. 7. 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. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 o Page 12 Regardless of the mitigation, some limited moisture/moisture vapor transmission through the slab 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 provi.de comment prior to the construction of the residential foundations or improvements. The vapor retarder contractor should have representatives onsite during the initial installation. WALL DESIGN PARAMETERS Conventional Retaining Walls The design parameters provided below assume that either non expansive soils (typically Class 2 permeable filter material or Class 3 aggregate base) or native onsite materials (up to and including an E.I. of 50) are used to backfill any retaining walls. The type of backfill (i.e., select or native), should be specified by the wall designer, and clearly shown on the plans. Building walls and exterior walls, below grade/underground, should be water- proofed. The foundation system for the proposed retaining walls should be designed in accordance with the recommendations presented in this and preceding sections of this rep9rt, as appropriate. Footings should be embedded a minimum of 18 inches below adjacent grade (excluding landscape layer, 6 inches) and should be 24 inches in width. There should be no.increase in bearing for footing width. Recommendations for specialty walls (i.e., crib, earthstone, geogrid, etc.) can be provided upon request, and would be based on site specific conditions. 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 pressure (EFP) of 65 pct; plus any applicable surcharge loading. For areas of male or re-entrant corners, the restrained wall design should extend a minimum distance of twice the height of the wall (2H) laterally from the corner. Cantilevered Walls The recommendations presented below are for cantilevered retaining walls up to 1 o feet high. Design parameters for walls less than 3 feet in height may be superceded by City of Carlsbad standard design. Active earth pressure may be used for retaining wall design, provided the top of the wall is not restrained from minor deflections. An equivalent fluid pressure approach may be used to compute the horizontal pressure against the wall. Appropriate fluid unit weights are given below for specific slope gradients of the retained material. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeaSails, Ine. W.O. 6087-A-SC June 16, 201 o Page 13 Level* 2 to 1 38 50 45 60 * Level backfill behind a retaining wall is defined as compacted earth materials, properly drained, without a slope for a distance of 2H behind the wall. ** As evaluated by testing, P.I. <15, E.I. <21, S.E. >30, and <10% passing No. 200 sieve. *** As evaluated by testin , P.I. <15, E.I. <50, ·s.E. >25. Seismic Surcharge for Retaining Walls For retaining walls that are over 6 feet in height, or within 6 feet or less of residences, that may impede ingress/egress, GSI recommends that the walls be evaluat!3d for a seismic surcharge (Section 1630A.1.1.5 of the 2007 CBC [CBSC, 2007]}. The site walls in this category should maintain an overturing Factor-of Safety (FOS) of about 1.2, when the seismic surcharge is applied. The seismic surcharge should be applied as a uniform load from the bottom of the footing (excluding shear keys), to the top of the backfill at the heel of the wall footing for restrained walls and an inverted triangular distribution for cantilever walls. This seismic surcharge pressure may be taken as 1 OH, where "H" is the dimension taken as the height of the retained material for the top of backfill. The resultant force should be applied at a distance 0 .6H 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. In addition to the above comments, GSI recommends that our field representative observe the temporary backcuts and footing excavations for the.walls. Temporary cuts for all wall installations should not exceed 1 :1 (h:v) inclinations, and should not be open for more than 90 days per cut, from start to finish. When wall configurations are finalized , the appropriate loading conditions for superimposed loads can be provided upon request. Retaining Wall Backfill and Drainage Positive drainage must be provided behind all retaining walls in the form of gravel wrapped in geofabric and outlets. A backdrain system is considered necessary for retaining walls that are 2 feet or greater in height. Details 1, 2, and 3, present the back drainage options discussed below. Backdrains should consist of a 4-inch diameter perforated PVC or ABS pipe encased in either Class 2 permeable filter material or ¾-inch to 1 ½-inch gravel wrapped in approved filter fabric (Mirafi 140 or equivalent). For low expansive backfill, the filter material should extend a minimum of 1 horizontal foot behind the base of the walls and upward at least 1 foot. For native backfill that has up to medium expansion potential, continuous Class 2 permeable drain materials should be used behind the wall. This material should be continuous (i.e., full height) behind the wall, A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeaSoils, Ine. W.O. 6087-A-SC June 16, 201 0 Page 14 (1) Waterproofing membrane-~ CMU or reinforced-concrete wall Proposed grade t - sloped to drain per precise civil drawings (5) Weep hole Footing and wall design by others,---"'-.- (1) Waterproofing membrane. (2) Gravel= Clean, crushed, ¾ to 1½ inch. Structural footing or settlement-sensitive !mprovement Provide surface drainage via an engineered \I-ditch (see civil plans for details) 2=1 (h=v) slope Native backfill 1=1 (h=v) or flatter backcut to be properly benched (6) Footing (3) Filter fabric: Mirafi 140N or approved equivalent. (4) Pipe= 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient sloped to suitable, approved outlet point (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surf ace. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. RETAINING WALL DETAIL -ALTERNATIVE A Detail 1 · <I .· -~ (1) Waterproofing membrane (optional)---. CMU or reinforced:._concrete wall J ._ 6 Inches -t (5) Weep hole Proposed grade sloped to drain per precise civil drawings ', \ \-(,y,,<~_/.)~\\ \-<\\',,<\-. '\~\ \,.,-\ \ \/.(,/4½\ \ ..-\ \ \ Footing and wall design by others --"'-...-..i Structural footing or settlement-sensitive improvement Provide surface drainage via engineered V-ditch (see civil plan details) 2=1 (h=v) slope ... .. ' .. . · . · ... . · .... Native backfill 1=1 (h=v) or flatter backcut to be properly benched ---(6) 1 cubic foot of ¾-inch crushed rock' (7) Footing (1) Waterproofing membrane (optional): Liquid boot or approved mastic equivalent. (2) Drain= Miradrain 6000 or J-drain 200 or equivalent for non-waterproofed walls; Miradrain 6200 or J-drain 200 or equivalent for waterproofed walls (all perforations down). (3) Filter fabric: Mirafi 140N or approved equivalent: place fabric flap behind core. (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surf ace. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Gravel= Clean, crushed, ¾ to 1½ inch. (7) Footing: If bench is created behind the f coting greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by . geotechnical consultant. RETAINING WALL DETAIL -ALTERNATIVE B Detail 2 <I .·. ~ (1) Waterproofing membrane-~ CMU or reinforced-concrete wall ---=t ±12 Inches 7- Structural footing or settlement-sensitive improvement r---Provide surface drainage 2=1 (h=v) slope ·:i-. •• : •• ~ : ...• . ·-.· . · ... ·:-·• .. ., ... ·. ~ (S) Weep hole H [ Proposed grade sloped to drain per precise civil (8) Native backfill (6) Clean drawif)Qs -'(0.~\\X\\~\~ Footing and wall qesign by others Heel .._I ----widl:--h __.,-i (3) Filter fabric (2) Gravel (4) Pipe (7) Footing (1) Waterproofing membrane: Liquid boot or approved masticequivalent. (2) Gravel= Clean, crushed, ¾ to 1½ inch. (3) Filter fabric= Mirafi 140N or approved equivalent. sand backfill 1=1 (h=v) or flatter backcut to be properly benched · (4) Pipe: 4-inch-diameter perforated PVC, Schedule 40, or approved alternative with minimum of 1 percent gradient to proper outlet point (perforations down). · (5) Weep hole: Minimum 2-inch diameter placed at 20-foot centers along the wall and placed 3 inches above finished surface. Design civil engineer to provide drainage at toe of wall. No weep holes for below-grade walls. (6) Clean sand backfill: Must have sand equivalent value (S.E.) of 35 or greater; can be densified by water jetting upon approval by geotechnical engineer. (7) Footing: If bench is created behind the footing greater than the footing width, use level fill or cut natural earth materials. An additional "heel" drain will likely be required by geotechnical consultant. (8) Native backfill: If El. (21 and S.E. L35 then all sand requirements also may not be required and will be reviewed by the geotechnical consultant. 11-. c • . RETAINING WALL DETAiL -ALTERNATIVE C Detail 3 and it should be constructed in accordance with the enclosed Detail 1 (Typical Retaining Wall Backfill and Drainage Detail). For limited access and confined areas, (panel) drainage behind the wall may be· constructed in accordance with Detail 2 (Retaining Wall Backfill and Subdrain Detail Geotextile Drain). Materials with an E.I. potential of greater than 50 should not be used as backfill for retaining walls. For more onerous expansive situations, backfill and drainage behind the retaining wall should conform with Detail 3 (Retaining Wall And Subdrain Detail Clean Sand Backfill). If gravel backdrains for the below- grade/underground walls are proposed, the drains should outlet via gravity or a sump pump this is doubly redundant. In lieu of backdrains, the below-grade/underground walls should be designed to additionally withstand the increased hydrostatic pressure, and not leak or become discolored. Outlets should consist of a 4-inch diameter solid PVC or ABS pipe spaced no greater than + 100 feet apart, with a minimum of two outlets, one on each end. The use of weep holes, only, in walls higher than 2 feet, is not recommended. The surface of the backfill should be sealed by pavement or the top 18 inches compacted with native soil (E.I. < 50). Proper surface drainage should also be provided. For additional mitigation, consideration should be given to applying a water-proof membrane to the back of all retaining structures. The use of a waterstop should be considered for all concrete and masonry joints. Wall/Retaining Wall Footing Transitions Site walls are anticipated to be founded on footings designed in accordance with the recommendations in this report. Should wall footings transition from cut to fill, the civil designer may specify either: a) A minimum of a 2-foot overexcavation and recompaction of cut materials for a distance of 2H, from the point of transition. 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 placed no greater than 20 feet on-:center, in accordance with the structural engineer's/wall designer's recommendations, regardless of whether or not transition conditions exist. Expansion joints should be sealed with a flexible, non-shrink grout. c) Embed the footings entirely into native formational material (i.e., deepened footings). 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 11a11 (above) and until such transition is between 45 and 90 degrees to the wall alignment. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 O Page 18 TOP-OF-SLOPE WALLS/FENCES/IMPROVEMENTS Slope Creep Soils at the site may be expansive and therefore, may become desiccated when allowed to dry. Such soils are susceptible to surficial slope creep, especially with seasonal changes in moisture content. Typically in southern California, during the hot and dry summer period, these soils become desiccated and shrink, thereby developing surface cracks. The extent and depth of these shrinkage cracks depend on many factors such as the nature and expansivity of the soils, temperature and humidity, and extraction of moisture from surface soils by plants and roots. When seasonal rains occur, water percolates into the cracks and fissures, causing slope surfaces to expand, with a corresponding loss in soil density and shear strength near the slope surface. With the passage of time and several moisture cycles, the outer 3 to 5 feet of slope materials experience a very slow, but progressive, outward and downward movement, known as slope creep. For slope heights greater than 1 o feet, this creep related soil movement will typically impact all rear yard flatwork and other secondary improvements that are located within about 15 feet from the top of slopes, such as swimming pools, concrete flatwork, etc., and in particular top of slope fences/walls. This influence is normally in the form of detrimental settlement, and tilting of the proposed improvements. The dessication/swelling and creep discussed above continues over the life of the improvements, and generally becomes progressively worse. Accordingly, this information should be provided to any homeowner. Top of Slope Walls/Fences Due to the potential for slope creep for slopes higher than about 1 o feet, some settlement and tilting of the walls/fence with the corresponding distresses, should be expected. To mitigate the tilting of top of slope walls/fences, we recommend that the walls/fences be constructed on deepened foundations without any consideration for creep forces, where the expansion index of the materials comprising the outer 15 feet of the slope is less than 50. The strength of the concrete and grout should be evaluated by the structural engineer of record. The proper ASTM tests for the concrete and mortar should be provided along with the slump quantities. The concrete used should be appropriate to mitigate corrosion, as warranted. DRIVEWAY, FLATWORK, AND OTHER IMPROVEMENTS The soil materials on site may be expansive. The effects of expansive soils are cumulative, and typically occur over the lifetime of any improvements. On relatively level areas, when the soils are allowed to dry, the dessication and swelling process tends to cause heaving and distress to flatwork and other improvements. The resulting potential for distress to improvements may be reduced, but not totally eliminated. To that end, it is recommended A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 o Page 19 that any homeowner be notified of this long-term potential for distress. To reduce the likelihood of distress, the following recommendations are presented for all exterior flatwork: 1. The subgrade area for concrete slabs should be compacted to achieve a minimum 90 percent relative compaction, and then be presoaked to 2 to 3 percentage points above (or 125 percent of) the soils' optimum moisture content, to a depth of 18 inches below subgrade elevation. If very low expansive soils are present, only optimum moisture content, or greater, is required and specific presoaking is not warranted. The moisture content of the subgrade should be proof tested within 72 hours prior to pouring concrete. 2. Concrete slabs should be cast over a non-yielding surface, consisting of a 4-inch layer of crushed rock, gravel, or clean sand, that should be compacted and level prior to pouring concrete. If very low expansive soils are present, the rock or gravel or sand may be deleted. The layer or subgrade should be wet-down completely prior to pouring concrete, to minimize loss of concrete moisture to the surrounding earth materials. 3. Exterior slabs should be a minimum of 4 inches thick. Driveway slabs and approaches should additionally have a thickened edge (12 inches) adjacent to all landscape areas, to help impede infiltration of landscape water under the slab. 4. The use of transverse and longitudinal control joints are recommended to help control slab cracking due to concrete shrinkage or expansion. Two ways to mitigate such cracking are: a) add a sufficient amount of reinforcing steel, increasing tensile strength of the slab; and, b) provide an adequate amount of control and/or expansion joints to accommodate anticipated concrete shrinkage and expansion. In order to reduce the potential for unsightly cracks, slabs should be reinforced at mid-height with a minimum of No. 3 bars placed at 18 inches on center, in each direction. If subgrade soils within the top 7 feet from finish grade are very low expansive soils (i.e., E.I. ~20), then 6x6-W1 .4xW1 .4 welded-wire mesh may be substituted for the rebar, provided the reinforcement is placed on chairs, at slab mid-height. The exterior slabs should be scored or saw cut, ½ to 3/s inches deep, often enough so that no section is greater than 1 o feet by 1 0 feet. For sidewalks or narrow slabs, control joints should be provided at intervals of every 6 feet. The slabs should be separated from the foundations and sidewalks with expansion joint filler material. 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. Concrete compression strength should be a minimum of 2,500 psi. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine.· W.O. 6087-A-SC June 16, 2010 Page 20 6. Driveways, sidewalks, and patio slabs adjacent to the house should be separated from the house with thick expansion joint filler material. In areas directly adjacent to a continuous source of moisture (i.e., irrigation, planters, etc.), all joints should be additionally sealed with flexible mastic. 7. Planters and walls should not be tied to the house. 8. Overhang structures should be supported on the slabs, or structurally designed with continuous footings tied in at least two directions. If very low expansion soils are present, footings need only be tied in one direction. 9. Any masonry landscape walls that are to be constructed throughout the property should be grouted and articulated in segments no more than 20 feet long. These segments should be keyed or doweled together. 1 O. Utilities should be enclosed within a closed utilidor (vault) or designed with flexible connections to accommodate differential settlement and expansive soil conditions. 11. Positive site drainage should be maintained at all times. Finish grade on the lots should provide a minimum of 1 to 2 percent fall to the street, as indicated herein. It should be kept in mind that drainage reversals could occur, including post-construction settlement, if relatively flat yard drainage gradients are not periodically maintained by the homeowner. 12. Air conditioning (NC) units should be supported by slabs that are incorporated into the building foundation or constructed on a rigid slab with flexible couplings for plumbing and electrical lines. NC waste water lines should be drained to a suitable non-erosive outlet. 13. Shrinkage cracks could become excessive if proper finishing and curing practices are not followed. Finishing and curing practices should be performed per the Portland Cement Association Guidelines. Mix design should incorporate rate of curing for climate and time of year, sulfate content of soils, corrosion potential of soils, and fertilizers used on site. 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 A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 21 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 (e.g., 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, as was done on this project. 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 1997 UBC and/or adopted California Building Code), positive structural separations (i.e., joints) between improvements, and stiffening and deepening of foundations. Expansion joints in walls should be placed no greater than 20 feet on-center, and in accordance with the structural engineer's recommendations. 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 any homeowner. 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 adversely.affects site improvements, and causes perched groundwater conditions. Graded slopes constructed 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. 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 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. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC . June 16, 2010 Page 22 Drainage Adequate lot surface drainage is a very important factor in reducing the likelihood of adverse performance offoundations, hardscape, and slopes. Surface drainage should be sufficientto 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, downspouts, or other appropriate means may be utilized to control roof drainage. Downspouts, 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 Graded 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 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 flatwork. If planters are constructed adjacent to structures, the sides and bottom of the planter should be provided with a moisture retarder to prevent penetration of irrigation water into the sub.grade. 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 A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, Ine. W.O. 6087-A-SC June 16, 201 O Page 23 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. 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 the homeowner and/or other interested parties. 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, flatwork, etc. 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 A&E Construction APN 215-070-39, Carlsbad Flle:e:\wp9\6000\6087a.gun Geo&oils, lne. W.O. 6087-A-SC June 16, 201 O Page 24 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 of the 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 of the 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 homeowners, etc., that may perform such work. 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 · A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 25 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 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 excavation. • During placement of subdrains, 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 retarders (i.e., visqueen, etc.). • During retaining wall subdrain installation, prior to backfill placement. • During placement of backfill for area drain, interior plumbi_ng, utility line trenches, and retaining wall backfill. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 26 • During slope construction/repair. • When any unusual soil conditions are encountered during any construction operations, subsequent to the issuance of this report. When any developer or homeowner improvements, such as flatwork, spas, pools, walls, etc., are constructed, prior to construction. 0 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. • GSI should review project sales documents to homeowner for geotechnical aspects, including irrigation practices, the conditions outlined above, etc., prior to any sales. At that stage, GSI will provide homeowners maintenance guidelines which should be incorporated into such documents. 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. 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 A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun GeoSoils, lne. W.O. 6087-A-SC June 16, 201 O Page 27 potential distress, the foundation and/or improvement's designer should confirm to GSI and the governing agency, in writing, that the 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 (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 of the area; however, soil and bedrock materials vary in characteristics 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. The conclusions and recommendations presented herein should be provided to all interested/affected parties. 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 of the project. A&E Construction APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun CeoSoils, lne. W.O. 6087-A-SC June 16, 2010 Page 28 The opportunity to be of service is greatly appreciated. If you have any questions, please do not hesitate to call our office. Attachments: Distribution: A&E Construction Appendix A -References Appendix B -General Earthwork, Grading Guidelines, and Preliminary Criteria (3) Addressee APN 215-070-39, Carlsbad File:e:\wp9\6000\6087a.gun W.O. 6087-A-SC June 16, 201 o Page29 GeoSoils, Ine. APPENDIX A ·REFERENCES APPENDIX A REFERENCES ACI Committee 318, 2008, Building code requirements for structural concrete (ACI 318-08) and commentary, dated January. ACI Committee 360, 2006, Design of slabs-on-ground (ACI 360R-06). ACI Committee 302, 2004, Guide for concrete floor and slab construction, ACI 302.1 R-04, dated June. · ACI 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, 1998, Standard practice for installation of water vapor retarder used in contact with earth or granular fill under concrete slabs, Designation: E 1643-98 (Reapproved 2005). __ , 1997, Standard specification for plastic water vapor retarders used in contact with soil or granular fill under concrete slabs, Designation: E 1745-97 (Reapproved 2004). CTL Thompson, 2005, Controlling moisture-related problems associated with basement slabs-on-grade in new residential construction. Californ!a· Building Standards Commission, 2007, California Building Code. GeoSoils, Inc., 2004a, Foundation plan review, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-B2-SC, dated October 7. __ , 2004b, Final compaction report of grading, Building pad area, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-B1-SC, dated September 14. --, 2004c, Geotechnical review of structural plans, Parcel 4, 6575 Black Rail Road, Carlsbad, San Diego County, California, W.O. 3460-A2-SC, dated August 23. __ , 2004d, Final compaction report of grading, Parcels 1 and 3, 6575 Black Rail Road, Carlsbad, S~n Diego County, California, W.O. 3460-8-SC, dated March 9. __ , 2003, Grading plan review, 6575 Black Rail Road, Proposed subdivision, City of Carlsbad, San Diego County, California, W.O. 3460-A1-SC, dated October 8. __ , 2002a, Soil corrosivity test results, 6575 Black Rail Road, City of Carlsbad, San Diego County, California, W.O. 3460-A1-SC, dated December 20. GeoSoils, lne. __ , 2002b, Preliminary geotechnical evaluation, 6575 Black Rail Road, Proposed subdivision, Carlsbad, San Diego County, California, W.O. 3460-A-SC, dated November 27. International Code Council, Inc., 2006, International building code and international residential code for one-and two-family dwellings. International Conference of Building Officials, 2001 , California building code, California code of regulations title 24, part 2, volume 1 and 2. __ , 1997, Uniform building code: Whittier, California, vol. 1, 2, and 3. Kanare, Howard, 2005, Concrete floors and moisture, Portland Cement Association, Skokie, Illinois. State of California, 201 O, Civil Code, Sections 895 et seq. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix A Page2 • I APPENDIX B · GENERAL EARiHWORK,_GRADING G_UI.DELINES. . AND PRELIMINARY CRITERIA . GENERAL EARTHWORK, GRADING GUIDELINES, AND PRELIMINARY CRITERIA General These guidelines present general procedures and requirements for earthwork and grading as shown on the approved grading plans, including preparation of areas to be filled, placement of fill, installation of subdrains, excavations, and appurtenant structures or flatwork. The recommendations contained in the geotechnical report are part of these earthwork and grading guidelines and would supercede the provisions contained hereafter in the case of conflict. Evaluations performed by the consultant during the course of grading may result in new or revised recommendations which could supercede these guidelines or the recommendations contained in the geotechnical report. Generalized details follow this text. The contractor is responsible for the satisfactory completion of all earthwork in ~ccordance with provisions of the project plans and specifications and latest adopted code. In the case of conflict, the most onerous provisions shall prevail. The project geotechnical engineer and engineering geologist (geotechnical consultant), and/or their representatives, should provide observation and testing services, and geotechnical consultation during the duration of the project. EARTHWORK OBSERVATIONS AND TESTING Geotechnical Consultant Prior to the commencement of grading, a qualified geotechnical consultant (soil engineer and engineering geologist) should be employed for the purpose of observing earthwork procedures and testing the fills for general conformance with the recommendations of the geotechnical report(s), the approved grading plans, and applicable grading codes and ordinances. The geotechnical consultant should provide testing and observation so that an evaluation may be made that the work is being accomplished as specified. It is the responsibility of the contractor to assist the consultants and keep them apprised of anticipated work schedules and changes, so that they may schedule their personnel accordingly. All remedial removals, clean-outs, prepared ground to receive fill, key excavations, and subdrain installation should be observed and documented by the geotechnical consultant prior to placing any fill. It is the contractor's responsibility to notify the geotechnical consultant when such areas are ready for observation. Laboratory and Field Tests Maximum dry density tests to determine the degree of compaction should be performed in accordance with American Standard Testing Materials test method ASTM designation D-1557. Random or representative field compaction tests should be performed in GeoSoils, lne. accordance with test methods ASTM designation D-1556, D-2937 or D-2922, and D-3017, at intervals of approximately ±2 feet of fill height or approximately every 1 ,ooo cubic yards placed. These criteria would vary depending on the soil conditions and the size of the project. The location and frequency of testing would be at the discretion of the geotechnical consultant. Contractor's Responsibility All clearing, site preparation, and earthwork performed on the project should be conducted by the contractor, with observation by a geotechnical consultant, and staged approval by the governing agencies, as applicable. It is the contractor's responsibility to prepare the ground surface to receive the fill, to the satisfaction of the geotechnical consultant, arid to place, spread, moisture condition, mix, and compact the fill in accordance with the recommendations of the geotechnical consultant. The contractor should also remove all non-earth material considered unsatisfactory by the geotechnical consultant. Notwithstanding the services provided by the geotechnical consultant, it is the sole responsibility of the contractor to provide adequate equipment and methods to accomplish the earthwork in strict accordance with applicable grading guidelines, latest adopted codes or agency ordinances, geotechnical report(s), and approved grading plans. Sufficient watering apparatus and compaction equipment should be provided by the contractor with due consideration for the fill material, rate of placement, and climatic conditions. If, in the opinion of the geotechnical consultant, unsatisfactory conditions such as questionable weather, excessive oversized rock or deleterious material, insufficient support equipment, etc., are resulting in a quality of work that is not acceptable, the consultant will inform the contractor, and the contractor is expected to rectify the conditions, and if necessary, stop work until conditions are satisfactory. During construction, the contractor shall properly grade all surfaces to maintain good drainage and prevent ponding of water. The contractor shall take remedial measures to control surface water and to prevent erosion of graded areas until such time as permanent drainage and erosion control measures have been installed. SITE PREPARATION All major vegetation, including brush, trees, thick grasses, organic debris, and other deleterious material, should be removed and disposed of off-site. These removals must be concluded prior to placing fill. In-place existing fill, soil, alluvium, colluvium, or rock materials, as evaluated by the geotechnical consultant as being unsuitable, should be removed prior to any fill placement. Depending upon the soil conditions, these materials may be reused as compacted fills. Any materials incorporated as part of the compacted fills should be approved by the geotechnical consultant. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page2 Any underground structures such as cesspools, cisterns, mining shafts, tunnels, septic tanks, wells, pipelines, or other structures not located prior to grading, are to be removed or treated in a manner recommended by the geotechnical consultant. Soft, dry, spongy, highly fractured, or otherwise unsuitable ground, extending to such a depth that surface processing cannot adequately improve the condition, should be overexcavated down to firm ground and approved by the geotechnical consultant before compaction and filling operations continue. Overexcavated and processed soils, which have been properly mixed and moisture conditioned, should be re-compacted to the minimum relative compaction as specified in these guidelines. Existing ground, which is determined to be satisfactory for support of the fills, should be scarified (ripped) to a minimum depth of 6 to 8 inches, or as directed by the geotechnical consultant. After the scarified ground is brought to optimum moisture content, or greater and mixed, the materials should be compacted as specified herein. If the scarified zone is greater than 6 to 8 inches in depth, it may be necessary to remove the excess and place the material in lifts restricted to about 6 to 8 inches in compacted thickness. Existing ground which is not satisfactory to support compacted fill should be overexcavated as required in the geotechnical report, or by the on-site geotechnical consultant. Scarification, disc harrowing, or other acceptable forms of mixing should continue until the soils are broken down and free of large lumps or clods, until ~he working surface is reasonably uniform and free from ruts, hollows, hummocks, mounds, or other uneven features, which would inhibit compaction as described previously. Where fills are to be placed on ground with slopes steeper than 5:1 (horizontal to vertical [h:v]), the ground should be stepped or benched. The lowest bench, which will act as a key, should be a minim!,Jm of 15 feet wide and should be at least 2 feet deep into firm material, and approved by the geotechnical consultant. In fill-over-cut slope conditions, the recommended minimum width of the lowest bench or key is also 15 feet, with the key founded on firm material, as designated by the geotechnical consultant. As a general rule, unless specifically recommended otherwise_ by the geotechnical consultant, the minimum width of fill keys should be equal to ½ the height of the slope. Standard benching is generally 4 feet (minimum) vertically, exposing firm, acceptable material. Benching may be used to remove unsuitable materials, although it is understood that the vertical height of the bench may exceed 4 feet. Pre-stripping may be considered for unsuitable materials in excess of 4 feet in thickness. All areas to receive fill, including processed areas, removal areas, and the toes of fill benches, should be observed and approved by the geotechnical consultant prior to placement of fill. Fills may then be properly placed and compacted until design grades (elevations) are attained. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page3 COMPACTED FILLS Any earth materials imported or excavated on the property may be utilized in the fill provided that each material has been evaluated to be suitable by the geotechnical consultant. These materials should be free of roots, tree branches, other organic matter, or other deleterious materials. All unsuitable materials should be removed from the fill as directed by the geotechnical consultant. Soils of poor gradation, undesirable expansion potential, or substandard strength characteristics may be designated by the consultant as unsuitable and may require blending with other soils to serve as a satisfactory fill material. Fill materials derived from benching operations should be dispersed throughout the fill area and blended with other approved material. Benching operations should not result in the benched material being placed only within a single equipment width away from the fill/bedrock contact. Oversized materials defined as rock, or other irreducible materials, with a maximum dimension greater than 12 inches, should not be buried or placed in fills unless the location of materials and disposal methods are specifically approved by the geotechnical consultant. Oversized material should be taken offsite, or placed in accordance with recommendations of the geotechnical consultant in areas designated as suitable for rock disposal. GSI anticipates that soils to be utilized as fill material for the subject project may contain some rock. Appropriately, the need for rock disposal may be necessary during grading operations on the site. From a geotechnical standpoint, the depth of any rocks, rock fills, or rock blankets, should be a sufficient distance from finish grade. This depth is generally the same as any overexcavation due to cut-fill transitions in hard rock areas, and generally facilitates the excavation of structural footings and substructures. Should deeper excavations be proposed (i.e., deepened footings, utility trenching, swimming pools, spas, etc.), the developer may consider increasing the hold-down depth of any rocky fills to be placed, as appropriate. In addition, some agencies/jurisdictions mandate a specific hold-down depth for oversize materials placed in fills. The hold-down depth, and potential to encounter oversize rock, both within fills, and occurring in cut or natural areas, would need to be disclosed to all interested/affected parties. Once approved by the governing agency, the hold-down depth for oversized rock (i.e., greater than 12 inches) in fills on this project is provided as 10 feet, unless specified differently in the text of this report. The governing agency may require that these materials need to be deeper, crushed, or reduced to less than 12 inches in maximum dimension, at their discretion. To facilitate future trenching, rock (or oversized material), should not be placed within the hold-down depth feet from finish grade, the range offoundation excavations, future utilities, or underground construction unless specifically approved by the governing agency, the geotechnical consultant, and/or the developer's representative. If import material is required for grading, representative samples of the materials to be utilized as compacted fill should be analyzed in the laboratory by the geotechnical consultant to evaluate it's physical properties and suitability for use onsite. Such testing A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, Ine. Appendix B Page4 should be performed three {3) days prior to importation. If any material other than that previously tested is encountered during grading, an appropriate analysis of this material should be conducted by the geotechnical consultant as soon as possible. Approved fill material should be placed in areas prepared to receive fill in near horizontal layers, that when compacted, should not exceed about 6 to 8 inches in thickness. The geotechnical consultant may approve thick lifts if testing indicates the grading procedures are such that adequate compaction is being achieved with lifts of greater thickness. Each layer should be spread evenly and blended to attain uniformity of material and moisture suitable for compaction. Fill layers at a moisture content less than optimum should be watered and mixed, and wet fill layers should be aerated by scarification, or should be blended with drier material. Moisture conditioning, blending, and mixing of the fill layer should continue until the fill materials have a uniform moisture content at, or above, optimum moisture. After each layer has been evenly spread, moisture conditioned, and mixed, it should be uniformly compacted to a minimum of 90 percent of the maximum density as evaluated by ASTM test designation D-1557, or as otherwise recommended by the geotechnical consultant. Compaction equipment should be adequately sized and should be specifically designed for soil compaction, or of proven reliability to efficiently achieve the specified degree of compaction. Where tests indicate that the density of any layer of fill, or portion thereof, is below the required relative compaction, or improper moisture is in evidence, the particular layer or portion shall be re-worked until the required density and/or moisture content has been attained. No additional fill shall be placed in an area until the last placed lift of fill has been tested and found to meet the density and moisture requirements, and is approved by the geotechnical consultant. In general, per the 1997 UBC and/or latest adopted version of the California Building Code {CBC), fill slopes should be designed and constructed at a gradient of 2:1 {h:v), or flatter. Compaction of slopes should be accomplished by over-building a minimum of 3 feet horizontally, and subsequently trimming back to the design slope configuration. Testing shall be performed as the fill is elevated to evaluate compaction as the fill core is being developed. Special efforts may be necessary to attain the specified compaction in the fill slope zone. Final slope shaping should be performed by trimming and removing loose materials with appropriate equipment. A final evaluation of fill slope compaction should be based on observation and/or testing of the finished slope face. Where compacted fill slopes are designed steeper than 2:1 (h:v), prior approval from the governing agency, specific material types, a higher minimum relative compaction, special reinforcement, and special grading procedures will be recommended. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page5 If an alternative to over-building and cutting back the compacted fill slopes is selected, then special effort should be made to achieve the required compaction in the outer 1 O feet of each lift of fill by undertaking the following: 1. An extra piece of equipment consisting of a heavy, short-shanked sheepsfoot should be used to roll (horizontal) parallel to the slopes continuously as fill is placed. The sheepsfoot roller should also be used to roll perpendicular to the slopes, and extend out over the slope to provide adequate compaction to the face of the slope. 2. Loose fill should not be spilled out over the face of the slope as each lift is compacted. Any loose fill spilled over a previously completed slope face should be trimmed off or be subject to re-rolling. 3. Field compaction tests will be made in the outer (horizontal) ±2 to ±8 feet of the slope at appropriate vertical intervals, subsequent to compaction operations. 4. After completion of the slope, the slope face should be shaped with a small tractor and then re-rolled with a sheepsfoot to achieve compaction to near the slope face. Subsequent to testing to evaluate compaction, the slopes should be grid-rolled to achieve compaction to the slope face. Final testing should be used to evaluate compaction after grid rolling. 5. Where testing indicates less than adequate compaction, the contractor will be responsible to rip, water, mix, and recompact the slope material as necessary to achieve compaction. Additional testing should be performed to evaluate compaction. SUBDRAIN INSTALLATION Subdrains should be installed in approved ground in accordance with the approximate alignment and details indicated by the geotechnical consultant. Subdrain locations or materials should not be changed or modified without approval of the geotechnical consultant. The geotechnical consultant may recommend and direct changes in subdrain line, grade, arid drain material in the field, pending exposed conditions. The location of constructed subdrains, especially the outlets, should be recorded/surveyed by the project civil engineer. Drainage at the subdrain outlets should be provided by the project civil engineer. EXCAVATIONS Excavations and cut slopes should be examined during grading by the geotechnical consultant. If directed by the geotechnical consultant, further excavations or overexcavation and refilling of cut areas should be performed, and/or remedial grading of A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, Ine .. Appendix B Page6 cut slopes should be performed. When fill-over-cut slopes are to be graded, unless otherwise approved, the cut portion of the slope should be observed by the geotechnical consultant prior to placement of materials for construction of the fill portion of the slope. The geotechnical consultant should observe all cut slopes, and should be notified by the contractor when excavation of cut slopes commence. If, during the course of grading, unforeseen adverse or potentially adverse geologic conditions are encountered, the geotechnical consultant should investigate, evaluate, and make appropriate recommendations for mitigation of these conditions. The need for cut slope buttressing or stabilizing should be based on in-grading evaluation by the geotechnical consultant, whether anticipated or not. Unless otherwise specified in geotechnical and geological report(s), no cut slopes should be excavated higher or steeper than that allowed by the ordinances of controlling governmental agencies. Additionally, short-term stability of temporary cut slopes is the contractor's responsibility. Erosion control and drainage devices should be designed by the project civil engineer and should be constructed in compliance with the ordinances of the controlling governmental agencies, and/or in accordance with the recommendations of the geotechnical consultant. COMPLETION Observation, testing, and consultation by the geotechnical consultant should be conducted during the grading operations in order to state an opinion that all cut and fill areas are graded in accordance with the approved project specifications. After completion of grading, and after the geotechnical consultant has finished observations of the work, final reports should be submitted, and may be subject to review by the controlling governmental agencies. No further excavation or filling should be undertaken without prior notification of the geotechnical consultant or approved plans. All finished cut and fill slopes should be protected from erosion and/or be planted in accordance with the project specifications and/or as recommended by a landscape architect. Such protection and/or planning should be undertaken as soon as practical after completion of grading. PRELIMINARY OUTDOOR POOL/SPA DESIGN RECOMMENDATIONS The following preliminary recommendations are provided for consideration in pool/spa design and planning. Actual recommendations should be provided by a qualified geotechnical consultant, based on site specific geotechnical conditions, including a subsurface investigation, differential settlement potential, expansive and corrosive soil potential, proximity of the proposed pool/spa to any slopes with regard to slope creep and lateral fill extension, as well as slope setbacks per code, and geometry of the proposed A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, Ine. Appendix B Page? improvements. Recommendations for pools/spas and/or deck flatwork underlain by expansive soils, or for areas with differential settlement greater than ¼-inch over 40 feet horizontally, will be more onerous than the preliminary recommendations presented below. The 1: 1 (h:v) influence zone of any nearby retaining wall site structures should be delineated on the project civil drawings with the pool/spa. This 1 :1 (h:v) zone is defined as a plane up from the lower-most heel of the retaining structure, to the daylight grade of the nearby building pad or slope. If pools/spas or associated pool/spa improvements are constructed within this zone, they should be re-positioned (horizontally or vertically) so that they are supported by earth materials that are outside or below this 1 : 1 plane. If this is not possible given the area of the building pad, the owner should consider eliminating these improvements or allow for increased potential for lateral/Vertical deformations and associated distress that may render these improvements unusable in the future, unless they are periodically repaired and maintained. The conditions and recommendations presented herein should be disclosed to all homeowners and any interested/affected parties. General 1 . The equivalent fluid pressure to be used for the pool/spa design should be 60 pounds per cubic foot (pct) for pool/spa walls with level backfill, and 75 pct for a 2:1 sloped backfill condition. In addition, backdrains should be provided behind pool/spa walls subjacent to slopes. 2. Passive earth pressure may be computed as an equivalent fluid having a density of 150 pct, to a maximum lateral earth pressure of 1 ,000 pounds per square foot (psf). 3. An allowable coefficient of friction between soil and concrete of 0.30 may be used with the dead load forces. 4. When combining passive pressure and frictional resistance, the passive pressure component should be reduced by one-third. 5. Where pools/spas are planned near structures, appropriate surcharge loads need to be incorporated into design and construction by the pool/spa designer. This includes, but is not limited to landscape berms, decorative walls, footings, built-in barbeques, utility poles, etc. 6. All pool/spa walls should be designed as "free standing" and be capable of supporting the water in the pool/spa without soil support. The shape of pool/spa in cross section and plan view may affect the performance of the pool, from a geotechnical standpoint. Pools and spas should also be designed in accordance with Section 1806.5 of the 1997 UBC. Minimally, the bottoms of the pools/spas, should maintain a distance H/3, where H is the height of the slope (in feet), from the slope face. This distance should not be less than 7 feet, nor need not be greater than 40 feet. A&E Construction File:e:\wp9\6000\6087a.gun CeoSoils, Ine. Appendix B Pages 7. The soil beneath the pool/spa bottom should be uniformly moist with the same stiffness throughout. If a-fill/cut transition occurs beneath the pool/spa bottom, the cut portion should be overexcavated to a minimum depth of 48 inches, and replaced with compacted fill, such that there is a uniform blanket that is a minimum of 48 inches below the pool/spa shell. If very low expansive soil is used for fill, the fill should be placed at a minimum of 95 percent relative compaction, at optimum moisture conditions. This requirement should be 90 percent relative compaction at over optimum moisture if the pool/spa is constructed within or near expansive soils. The potential for grading and/or re-grading of the pool/spa bottom, and attendant potential for shoring and/or slot excavation, needs to be considered during all aspects of pool/spa planning, design, and construction. 8. If the pool/spa is founded entirely in compacted fill placed during rough grading, the deepest portion of the pool/spa should correspond with the thickest fill on the lot. 9. Hydrostatic pressure relief valves should be incorporated into the pool and spa designs. A pool/spa under-drain system is also recommended, with an appropriate outlet for discharge. 10. All fittings and pipe joints, particularly fittings in the side of the pool or spa, should be properly sealed to prevent water from leaking into the adjacent soils materials, and be fitted with slip or expandible joints between connections transecting varying soil conditions. 11 . An elastic expansion joint (flexible waterproof sealant) should be installed to prevent water from seeping into the soil at all deck joints. 12. A reinforced grade beam should be placed around skimmer inlets to provide support and mitigate cracking around the skimmer face. 13. In order to reduce unsightly cracking, deck slabs should minimally be 4 inches thick, and reinforced with No. 3 reinforcing bars at 18 inches on-center. All slab reinforcement should be supported to ensure proper mid-slab positioning during the placement of concrete. Wire mesh reinforcing is specifically not recommended. Deck slabs should not be tied to the pool/spa structure. Pre-moistening and/or pre-soaking of the slab subgrade is recommended, to a depth of 12 inches (optimum moisture content), or 18 inches (120 percent of the soil's optimum moisture content, or 3 percent over optimum moisture content, whichever is greater), for very low to low, and medium expansive soils, respectively. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. Slab underlayment should consist of a 1-to 2-inch leveling course of sand (S,E. >30) and a minimum of 4 to 6 inches of Class 2 base compacted to 90 percent. Deck slabs within the H/3 zone, where H is the height of the slope (in feet), will have an increased potential for distress relative to other areas outside of the H/3 zone. If distress is undesirable, A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, Ine. Appendix B Page9 improvements, deck slabs or flatwork should not be constructed closer than H/3 or 7 feet (whichever is greater) from the slope face, in order to · reduce, but not eliminate, this potential. · 14. Pool/spa bottom or deck slabs should be founded entirely on competent bedrock, or properly compacted fill. Fill should be compacted to achieve a minimum 90 percent relative compaction, as discussed above. Prior to pouring concrete, subgrade soils below the pool/spa decking should be throughly watered to achieve a moisture content that is at least 2 percent above optimum moisture content, to a depth of at least 18 inches below the bottom of slabs. This moisture content should be maintained in the subgrade soils during concrete placement to promote uniform curing of the concrete and minimize the development of unsightly shrinkage cracks. 15. In order to reduce unsightly cracking, the outer edges of pool/spa decking to be bordered by landscaping, and the edges immediately adjacent to the pool/spa, should be underlain by an 8-inch wide concrete cutoff shoulder (thickened edge) extending to a depth of at least 12 inches below the bottoms of the slabs to mitigate excessive infiltration of water under the pool/spa deck. These thickened edges should be reinforced with two No. 4 bars, one at the top and one at the bottom. Deck slabs may be minimally reinforced with No. 3 reinforcing bars placed at 18 inches on-center, in both directions. All slab reinforcement should be supported on chairs to ensure proper mid-slab positioning during the placement of concrete. 16. Surface and shrinkage cracking of the finish slab may be reduced if a low slump and water-cement ratio are maintained during concrete placement. Concrete utilized should have a minimum compressive strength of 4,000 psi. Excessive water added to concrete prior to placement is likely to cause shrinkage cracking, and should be avoided. Some concrete shrinkage cracking, however, is unavoidable. 17. Joint and sawcut locations for the pool/spa deck should be determined by the design engineer and/or contractor. However, spacings should not exceed 6 feet on center. 18. Considering the nature of the 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), should be anticipated. All excavations should be observed by a representative of the geotechnical consultant, including the project geologist and/or geotechnical engineer, prior to workers entering the excavation or trench, and minimally conform to Cal/OSHA ('Type C" soils may be assumed), state, and local safety codes. Should adverse conditions exist, appropriate recommendations should be offered at that time by the geotechnical consultant. GSI does not consult in the area of safety engineering and the safety of the construction crew is the responsibility of the pool/spa builder. A&E Construction Flle:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page 10 19. It is imperative that adequate provisions for surface drainage are incorporated by the homeowners into their overall improvement scheme. Ponding water, ground saturation and flow over slope faces, are all situations which must be avoided to enhance long term performance of the pool/spa and associated improvements, and reduce the likelihood of distress. 20. Regardless of the methods employed, once the pool/spa is filled with water, should it be emptied, there exists some potential that if emptied, significant distress may occur. Accordingly, once filled, the pool/spa should not be emptied unless evaluated by the geotechnical consultant and the pool/spa builder. · 21 . For pools/spas built within (all or part) of the 1997 Uniform Building Code (UBC) setback and/or geotechnical setback, as indicated in the site geotechnical documents, special foundations are recommended to mitigate the affects of creep, lateral fill extension, expansive soils and settlement on the proposed pool/spa. Most municipalities or County reviewers do not consider these effects in pool/spa plan approvals. As such, where pools/spas are proposed on 20 feet or more of fill, medium or highly expansive soils, or rock fill with limited "cap soils" and built within 1997 UBC setbacks, or within the influence of the creep zone, or lateral fill extension, the following should be considered during design and construction: OPTION A: Shallow foundations with or without overexcavation of the pool/spa "shell," such that the pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater that 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. GSI recommends a pool/spa under-drain or blanket system (see attached Typical Pool/Spa Detail). The pool/spa builders and owner in this optional construction technique should be generally satisfied with pool/spa performance under this scenario; however, some settlement, tilting, cracking, and leakage of the pool/spa is likely over the life of the project. OPTION B: Pier supported pool/spa foundations with or without overexcavation of the pool/spa shell such that the pool/spa is surrounded by 5 feet of very low to low expansive soils (without irreducible particles greater than 6 inches), and the pool/spa walls closer to the slope(s) are designed to be free standing. The need for a pool/spa under-drain system may be installed for leak detection purposes. Piers that support the pool/spa should be a minimum of 12 inches in diameter and at a spacing to provide vertical and lateral support of the pool/spa, in accordance with the. pool/spa designers recommendations, local code, and the 1997 UBC. The pool/spa builder and owner in this second scenario construction technique should be more satisfied with pool/spa performance. This construction . will reduce settlement and creep effects on the pool/spa; however, it will not eliminate these potentials, nor make the pool/spa "leak-free." A&E Construction File:e:\wp9\6D00\6087a.gun GeoSoils, Ine. Appendix B Page 11 22. The temperature of the water lines for spas and pools may affect the corrosion properties of site soils, thus, a corrosion specialist should be retained to review all spa and pool plans, and provide mitigative recommendations, as warranted. Concrete mix design should be reviewed by a qualified corrosion consultant and materials engineer. 23. All pool/spa utility trenches should be compacted to 90 percent of the laboratory standard, under the full-time observation and testing of a qualified geotechnical consultant. Utility trench bottoms should be sloped away from the primary structure on the property (typically the residence). 24. Pool and spa utility lines should not cross the primary structure's utility lines (i.e., not stacked, or sharing of trenches, etc.). 25. The pool/spa or associated utilities should not intercept, interrupt, or otherwise adversely impact any area drain, roof drain, or other drainage conveyances. If it is necessary to modify, move, or disrupt existing area drains, subdrains, or tightlines, then the design civil engineer should be consulted, and mitigative measures provided. Such measures should be further reviewed and approved by the geotechnical consultant, prior to proceeding with any further construction. · 26. The geotechnical consultant should review and approve all aspects of pool/spa and flatwork design prior to construction. A design civil engineer should review all aspects of such design, including drainage and setback conditions. Prior to acceptance of the pool/spa construction, the project builder, geotechnical consultant and civil designer should evaluate the performance of th~ area drains and other site drainage pipes, following pool/spa construction. 27. All aspects of construction should be reviewed and approved by the geotechnical consultant, including during excavation, prior to the placement of any additional fill, prior to the placement of any reinforcement or pouring of any concrete. 28. Any changes in ~esign or location of the pool/spa should be reviewed and approved by the geotechnical and design civil engineer prior to construction. Field adjustments should not be allowed until written approval of the proposed field changes are obtained from the geotechnical and design civil engineer. 29. Disclosure should be made to homeowners and builders, contractors, and any interested/affected parties, that pools/spas built within about 15 feet of the top of a slope, and/or H/3, where H is the height of the slope (in feet), will experience some movement or tilting. While the pool/spa shell or coping may not necessarily crack, the levelness of the pool/spa will likely tilt toward the slope, and may not be esthetically pleasing. The same is true with decking, flatwork and other improvements in this zone. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix 8 Page 12 30. Failure to adhere to the above recommendations will significantly increase the potential for distress to the pool/spa, flatwork, etc. 31. Local seismicity and/or the design earthquake will cause some distress to the pool/spa and decking or flatwork, possibly including total functional and economic loss. 32. The information and recommendations discussed above should be provided to any contractors and/or subcontractors, or homeowners, interested/affected parties, etc., that may perform or may be affected by such work. JOB SAFETY General At GSI, getting the job done safely is of primary concern. The following is the company's safety considerations for use by all employees on multi-employer construction sites. On-ground personnel are at highest risk of injury, and possible fatality, on grading and construction projects. GSI recognizes that construction activities ·wm vary on each site, and that site safety is the prime responsibility of the contractor; however, everyone must be safety conscious and responsible at all times. To achieve our goal of avoiding accidents, cooperation between the client, the contractor, and GSI personnel must be maintc;1ined. In an effort to minimize risks associated with geotechnical testing and observation, the following precautions are to be implemented for the safety of field personnel on grading and construction projects: Safety Meetings: GSI field personnel are directed to attend contractor's regularly scheduled and documented safety meetings. Safety Vests: Safety vests are provided for, and are to be worn by GSI personnel, at all times, when they are working in the field. Safety Flags: Two safety flags are provided to GSI field technicians; one is to be affixed to the vehicle when on site, the other is to be placed atop the spoil pile on all test pits. Flashing Lights: All vehicles stationary in the grading area shall use rotating or flashing amber beacons, or strobe lights, on the vehicle during all field testing. While operating a vehicle in the grading area, the emergency flasher on the vehicle shall be activated. In the event that the contractor's representative observes any of our personnel not following the above, we request that it be brought to the attention of our office. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, Ine. Appendix B Page 13 Test Pits Location, Orientation, and Clearance The technician is responsible for selecting test pit locations. A primary concern should be the technician's safety. Efforts will be made to coordinate locations with the grading contractor's authorized representative, and to select locations following or behind the established traffic pattern, preferably outside of currenttraffic. The contractor's authorized representative (supervisor, grade checker, dump man, operator, etc.) should direct excavation of the pit and safety during the test period. Of paramount concern should be the soil technician's safety, and obtaining enough tests to represent the fill. Test pits should be excavated so that the spoil pile is placed away from oncoming traffic, whenever possible. The technician's vehicle is to be placed next to the test pit, opposite the spoil pile. This necessitates the fill be maintained in a driveable condition. Alternatively, the contractor may wish to park a piece of equipment in front of the test holes, particularly in small fill areas or those with limited access. A zone of non-encroachment should be established for all test pits. No grading equipment should enter this zone during the testing procedure. The zone should extend approximately 50 feet outward from the center of the test pit. This zone is established for safety and to avoid excessive ground vibration, which typically decreases test results. When taking slope tests, the technician should park the vehicle directly above or below the test location. If this is not possible, a prominent flag should be placed at the top of the slope. The contractor's representative should effectively keep all equipment at a safe operational distance (e.g., 50 feet) away from the slope during this testing. The technician is directed to withdraw from the active portion of the fill as soon as possible following testing. The technician's vehicle should be parked at the perimeter of the fill in a highly visible location, well away from the equipment traffic pattern. The contractor should inform our personnel of all changes to haul roads, cut and fill areas or other factors that may affect site access and site safety. In the event that the technician's safety is jeopardized or compromised as a result of the contractor's failure to comply with any of the above, the technician is required, by company policy, to immediately withdraw and notify his/her supervisor. The grading contractor's representative will be contacted in an effort to affect a solution. However, in the interim, no further testing will be performed until the situation is rectified. Any fill placed can be considered unacceptable and subject to reprocessing, recompaction, or removal. In the event that the soil technician does not comply with the above or other established safety guidelines, we request that the contractor bring this to the technician's attention and notify this office. Effective communication and coordination between the contractor's representative and the soil technician is strongly encouraged in order to implement the above safety plan. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, Ine. Appendix B Page 14 Trench and Vertical Excavation It is the contractor's responsibility to provide safe access into trenches where compaction testing is needed. Our personnel are directed not to enter any excavation or vertical cut which: 1) is 5 feet or deeper unless shored or laid. back; 2) displays any evidence of instability, has any loose rock or other debris which could fall into the trench; or 3) displays any other evidence of any unsafe conditions regardless of depth. All trench excavations or vertical cuts in excess of 5 feet deep, which any person enters, should be shored or laid back. Trench access should be provided in accordance with Cal/OSHA and/or state and local standards. Our personnel are directed not to enter any trench by being lowered or "riding down" on the equipment. If the contractor fails to provide safe access to trenches for compaction testing, our company policy requires that the soil technician withdraw and notify his/her supervisor. The contractor's representative will be contacted in an effort to affect a solution. All backfill not tested due to' safety concerns or other reasons could be subject to reprocessing and/or removal. If GSI personnel become aware of anyone working beneath an unsafe trench wall or vertical excavation, we have a legal obligation to put the contractor and owner/developer on notice to immediately correct the situation. If corrective steps are not taken, GSI then has an obligation to notify Cal/OSHA and/or the proper controlling authorities. A&E Construction File:e:\wp9\6000\6087a.gun GeoSoils, lne. Appendix B Page 15 Original ground surface to be restored with compacted fill I Back-cut varies. For deep removals, backcut should be made no steeper than 1=1 (HV), or flatter as necessary for safety considerations. 2D / Toe of slope as shown on grading plan < :tS.i: .. :>• _:::-i> .-<.:·-· ... : .. : ·· .. : ·compa~~~d.F.111 -:.:· .. <:,:/.\· .: .. _., ·,·•.~ . .:'._ .. _:·: : ... :.--••.•.~: -~.:--.-: •,• .. •· .. ,'••••,·.:. ~/ 0 "' / I \__ Original ground surface of ~ <f-/ D • Anticipated removal of unsuitable material .~..s/ (depth per geolechnlcal engineer) ~~/ 'I(' Provide a 1:1 (H:V) minimum projection from toe of slope as shown on grading plan to the recommended removal depth. Slope height, site conditions, and/ or local conditions could dictate flatter projections. '!!Le. J1:l· FILL SLOPE TOEING OUT ON FLAT ALLUVIATED CANYON DETAIL Plate 8-3 Proposed grade~ ---- Previously placed, temporary compacted fill for drainage only ------ Proposed additional compacted fill Ex~ling co 9~~@: II tt:£'@D.P;/4 P~< mpacted fill 91· -.:-:-:-:-:::::-:-:-:-::::::-:-7"· · -: · ·: t/nsu1·~p · =-· ·: .-· .. ': .... ·' •· ·. '· ~.# '-· ..... .../ • • La le mat ... . ~-: · · · · · · · · · · · · · · · · · · · · · er.1al (t · · · s, s;-:-:-:-:-::::•:'.,, . . ,:: , ... ; , . ·, ·:. ,. · ... _. ... : ' ... >, .. !3>. bEi· remo ) : .• _-. : ... · ·:% :X:'0'""~ ;,; · . .. ved ~"-?.2~\\~\'1/) 00~~,>;;;-\\\;<~\W"< ./\0/\~ y\ ,'<<-' To be remo Bedrock or a additional c;ed before placing --native materiaf proved mpacted fill la . c. . REMOVAL ADJACENT TO EXISTING FILL ADJOINING CANYON FILL DETAIL Plate 8-4 Toe of slope as shown on grading plan .,,,---Proposed grade \ / / / Natural slope to be restored with compacted fill / Compacted fill / / / Backcut varies 4-foot minimum ----~r Subdrain by geotechnical consultant NOTES: 1. Where the natural slope approaches or exceeds the design slope ratio, special recommendations would be provided by the geotechnical consultant. · 2. The need for and disposition of drains should be evaluated by the geotechnical consultant, based upon exposed conditions. 'It.. lire:. FILL OVER NATURAL (SIDEHILL FILL) DETAIL Plate 8-7 • Proposed finish grade -~ Natural grade ---------------------------,.., -,, H • height of elope -----i ~ .. : . ·:· : : ; ~ ~-i. •. ····:·_. -. · •.. ·• -~ . ... · .. :-·. . . . . . . . : .. Typical benching (4-foot minimum) Subdrain as recommended by geotechnical consultant NOTES= 1. 15-f oot minimum to be maintained from proposed finish slope face to back cut. minimum 2. The need and disposition of drains will be evaluated by the geotechnical consultant based on field conditions. 3. Pad overexcavation and recompaction should be performed if evaluated to be necessary by the geotechnical consultant. ·'it. , ... c. SKIN FILL OF NATURAL GROUND DETAIL Plate 8-10 Natural grade Proposed pad grade .. -~-·---..~··L--·,..-::. _ _ _._._..~ J_ CUT LOT OR MATERIAL -TYPE TRANSITION Typical benching ( 4-foot minimum) Bedrock or approved native material Natural grade ... ···•:. . ... -.=~--.. ':~ .. · .... ,· j_ · _______ _ * Deeper overexcavation may be recommended by the geotechnical consultant in steep cut-fill transition areas, such that the underlying topography is no steeper than 3=1 (H:V) CUT-FILL LOT (DAYLIGHT TRANSITION) • . e .. . TRANSITION LOT DETAILS Plate 8-12 MAP VIEW NOT TO SCALE Concrete cut-off wall SEE NbTEI~ _s __________ j B I Top of !dope ~ Gravity-flow, nonperforated subdrain · I=== we (transverse) Toe of slope 4 I 1 steel Pool 4-inch perforated subdrain pipe (longitudinal) Coping A' 4-inch perforated subdrain pipe (transverse} Pool Direction of drainage B' CROSS SECTION VIEW Coping NOTTO SCALE SEE NOTES 2-inch-thick sand layer Pool encapsulated in 5-foot thickness of sand --~ B r H Gravity-flow nonperforated subdraln pipe 6-inch-thick gravel layer 4-inch perforated subdrain pipe Coping I I . -1 1 steet 2-inch-thlck sand layer · Vapor retarder Perforated subdrain pipe NOTES: 1. 6-inch-thick. clean gravel (¾ to 1½ inch} sub-base encapsulated in Mirafi 140N or equivalent, underlain by a 15-mil vapor retarder, with 4-inch-diameter perforated pipe longitudinal connected to 4-inch-diameter perforated pipe transverse. Connect transverse pipe to 4-inch-diameter nonperforated pipe at low point and outlet or to sump pump area 2. 3 . Pools on fills thicker than 20 feet should be constructed on deep foundations; otherwise, distress (tilting, cracking, etc.) should be expected. · Design does not apply to infinity-edge pools/ spas. • •• c •. . TYPICAL POOL/SPA DETAIL Plate 8-17 SIDE VIEW Test pit TOP VIEW Flag Spoil pile Light .. . . . . .. . . ~ . . ,. '• . . ... . . . . -~__.."-'---'-I Vehicle -------50 feet------.------50 feet------1-ii ------------,00 fee1--------------1--. TEST PIT SAFETY DIAGRAM Plate 8-20