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HomeMy WebLinkAboutMS 05-02; FIDELMAN PROJECT; UPDATED GEOTECHNICAL INVESTIGATION & FOUNDATION RECOMMENDATIONS; 2013-10-30ENGINEERINC] rt:,. Kl. \i!}l lil~\l ! CU~iJlHl:tf.l. (1~1/~ ll!l,;:;n~:t! rn Q.~!Q~.2~Q~ ., 2121 Montiel Road, San Marcos, California 9?.0o(l • (7Li0) t\'.N-nu;~ • ht., (i'60) 400-7477 • www.c.lesig11grourc::.1.co111 -~ UPDATED GEO TECHNICAL INVEST/GA TION & FOUNDATION RE COMMENDATIONS PROPOSED SUBDIVISION LOCATED AT 4400 PARK DRIVE, CARLSBAD, CALIFORNIA EDG Project No. 135229-1 October 30, 2013 PREPARED FOR: Lucy Ann Hall Trust Lucy Ann Hall and Allen Sweet P.O. Box 4230 Carlsbad, CA 92018 \ . ,. l,f(Il~(Hi1ll',',t_ f:IVll ~IRll("lllh~l (, .:1R)HlfflllKii.t ! i_'IL:t:U;1:1·:: r,1ii ii(',1flr.tHL.:..! i, l'.Or.1~.l[k!,\l ~·:rn-1:;1Hu,::11111 2121 Montiel Road, San Marcos, California 92069, (760) 839-7302 • Fax (760) 480-7477 • www.desig11groupca.com Date: To: October 30, 2013 Lucy Ann Hall Trust Lucy Ann Hall and Allen Sweet P.O. Box 4230 Carlsbad, CA 92018 I uan n .hall@sbcgloba I.net Re: New development to be located at 4400 Park Drive, Carlsbad, California Subject: Updated Geotechnical Investigation and Report In accordance with your request and our signed proposal, dated August 6, 2013, we have performed a limited subsurface investigation of the subject site for the proposed new residence. The findings of the investigation, earthwork recommendations and foundation design parameters are presented in this report. In general it is our opinion the proposed construction, as described herein, is feasible from a geotechnical standpoint, provided the recommendations of this report and generally accepted construction practices are followed. If you have any questions regarding the following report please do not hesitate to contact our office. Sincerely, ENGINEERING DESIGN GROUP Steven Norris California GE#2590 Erin E. Rist California RCE #65122 TABLE OF CONTENTS Section 1 2 3 SCOPE SITE AND PROJECT DESCRIPTION ......... . FIELD INVEST/GA T/ON .............................. . 4 SUBSOIL CONDITIONS ............................. . 5 GROUND WATER ..................................... . 6 LIQUEFACTION ........................... . . ' ........ 1 . . . 1 . '. 1 .. 1 . .. 2 7 CONCLUSIONS ANO RECOMMENDATIONS ......................................................... 3 7.1 GENERAL ................................................................................. 3 7.2 EARTHWORK. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...................... 3 7.3 FOUNDATIONS... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.4 CONCRETE SLABS ON GRADE ............... . . . ' .... 6 7.5 RETAINING WALLS ................ . . . "'....... 7 7.6 SURFACE DRAINAGE ................... . . ...... 9 8 CONSTRUCTION OBSERVATION AND TESTING ...................................................... 9 9 MISCELLANEOUS ............................................................................. 10 FIGURES Site Vicinity Map ......................................................................... Figure No. 1 Site Location Map.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .............. Figure No. 2 Site Plan ................................................................................... Figure 3 Boring Logs .............................................................................. Borings 1-4 Cross Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 APPENDICES References.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ......... . General Earthwork and Grading Specifications ............................................... . Retaining Wall Drainage Detail ............................................................ . Appendix A Appendix B Appendix C 1 SCOPE This updated report gives our recommendations for the proposed lot division located at 4400 Park Drive, Carlsbad, California. (See Figure No. 1, "Site Vicinity Map", and Figure No. 2, "Site location Map"). The scope of our work conducted onsite to date has included a visual reconnaissance of the property and surrounding areas, a limited subsurface investigation of the subject property, review of past reports, research at City of Carlsbad, and preparation of this report presenting our findings, conclusions and recommendations. At the time of this report the preliminary grading plan was available for review although building plans have not been developed 2 SITE AND PROJECT DESCRIPTION The subject property is generally in a similar condition to that described in our original report (Ref. No. 7). The property is bordered to the north, south and east by similar single family dwellings, and to the west by Yuki lane. The general topography of the site area consists of coastal foothill terrain. The topography of the site itself consists of a relatively flat, previously graded, upper building pads at the residence and detached garage, a graded driveway and a lower pad the generally descends sloping east to west and north to south. The northern portion of the upper pad is flanked by an oversteepened slope of approximately 20 feet. The property is currently developed with a pre-existing single family dwelling constructed on a slab on grade foundation and detached garage structure. Our review of tax records indicates the existing structure was constructed in approximately 1961. Based upon our discussions with the owner and review of the preliminary grading plan we understand the development will consist of the division of the property into three lots and grading associated with the lot creation. 3 FIELD INVEST/GA TION Our field investigation of the property consisted of a site reconnaissance, site field measurements, observation of existing conditions on-site and on adjacent sites, and a limited subsurface investigation of soil conditions. Our subsurface investigation consisted of visual observation of four exploratory boring excavations in the general areas of proposed construction, logging of soil types encountered, and sampling of soils for laboratory testing. The locations of our borings are given in Figure No. 3, "Boring location Map". 4 SUBSOIL CONDITIONS Based upon our subsurface investigation of the property the site soil profiles and soil types are described in general as follows: Fill/Weathered: Fill and weathered soil profiles consisting of slightly silty sands. These profiles extend to depths between approximately 8 to 15 feet below adjacent grade. The materials consist of dark to light brown, slightly moist, medium dense, silty sands with roots. Fill and weathered materials are not considered suitable for the support of structures in their present state. Slightly silty sands classify as SW-SM according to the Unified Classification System, and based on visual observation generally possess potentials for expansion in the low range. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEERING DESIGN GROUP GEOTECHNICAL' CIVIL, ST RU Cl URAL CON!:.,UL r AN Is Page No. 1 Job No. 135229-1 Sandstone: Sandstone materials were found to underlie the fill and weathered material within our boring excavations. These materials consisted reddish brown to tan to grey, moist, dense to very dense slightly silty sandstone. Sandstone materials are considered suitable for the support of structures and structural improvements, provided the recommendations of this report are followed. Sandstone materials classify as SW-SM according to the Unified Classification System, and based on visual observation, laboratory testing and our experience possess potentials for expansion in the low range. Detailed logs of our exploratory borings are attached herein Boring Logs Nos. 1-4. 5 GROUND WATER Static ground water was not identified in our subsurface investigations. Groundwater is not anticipated to be a significant concern to the project provided the recommendations of this report are followed. However, in our experience groundwater conditions can develop where no such condition previously existed. If groundwater conditions are encountered during site excavations, a slab underdrain systems may be required. In consideration of the clean, friable sand layer encountered during the subsurface investigation, onsite infiltration shall be limited. Any proposed bioretention facilities shall be lined with an impervious vapor barrier. Proper surface drainage and irrigation practices will play a significant role in the future performance of the project. Please note in the "Concrete Slab on Grade" section of this report for specific recommendations regarding water to cement ratio for moisture sensitive areas should be adhered. The project architect and/or waterproofing consultant shall specifically address waterproofing details. 6 LIQUEFACTION It is our opinion that the site could be subjected to moderate to severe ground shaking in the event of a major earthquake along any of the faults in the Southern California region. However, the seismic risk at this site is not significantly greater than that of the surrounding developed area. Liquefaction of cohesion less soils can be caused by strong vibratory motion due to earthquakes. Hesearch and historical data indicate that loose, granular soils underlain by a near-surface ground water table are most susceptible to liquefaction, while the stability of most silty clays and clays is not adversely affected by vibratory motion. Because of the dense nature of the soil materials underlying the site and the lack of near surface water, the potential for liquefaction or seismically-induced dynamic settlement at the site is considered low. The effects of seismic shaking can be reduced by adhering to the most recent edition of the Uniform Building Code and current design parameters of the Structural Engineers Association of California. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEERING DESIGN GROUP GEO fECHN1CAL, CIVIL, STRUCTURAL CONSUL I Al-ITS Page No. 2 Job No. 135229-1 7 CONCLUSIONS AND RECOMMENDATIONS 7.1 GENERAL In general it is our opinion the proposed construction, as discussed and de,cribed herein, is feasible from J geotechnical standpoint, provided the recommendations of this report are followed. Based upon our review of past grading plans and our subsurface investigation we anticipate removills and recompaction on the order of 8-15 feet in the lower pad area. In consideration of the oversteepened slope condition at the north portion of the property and the observed erosion along the toe of the steep hillside a sufficient horizontal setback from the toe of the hillside on the order of 10 feet should be maintained. In addition a debris fence or wall should be constructed at the toe of the slope at the time of building development to limit erosion toward building structures. 7.2 EARTHWORK Grading should be conducted in accordance with the recommendations below as well as Appendix B of this report, as applicable. 7.2.1 Site Preparation Prior to any grading, the areas of proposed improvement should be cleared of surface and subsurface debris (including organic topsoil, vegetative and construction debris). Removed debris should be properly disposed of off- site prior to the commencement of any fill operations. Holes resulting from the removal of debris, existing structures, or other improvements which extend below the undercut depths noted, should be filled and compacted using onsite material or an import material with a very low potential for expansion. 7.2.2 Removals Fill and weathered profiles found to mantle the site in our boring excavations, upper approximately 8-15 feet on the lower pad, as observed in the field, are not suitable for the structurnl support of buildings or structural improvements in their present state. In general we recommend a removal and recompaction in the areas of new settlement sensitive improvements. In consideration of the depth of unsuitable profiles and the proposed new slopes and improvement limits, we anticipate the new building pads will be re-graded. In general grading should consist of the removal of unsuitable soil profiles to establish suitable keyways and subgrade bottoms, scarification of subgrade to a minimum depth of 12 inches, benching out of pre-existing unsuitable profiles and the re-compaction of fill materials to 90 percent minimum relative compaction. Where new slopes and walls support new drivewc1ys, removals are anticipated along the edge of existing fill slopes. Excavated fill materials are suitable for re-use as fill material during grading provided they are cleaned of debris and oversize material in excess of 6 inches in diameter (oversized material is not anticipated to be of significant concern) and are free of contamination. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINh"JlRING DESIGN G'ROUP GEOTECHNICAL, CIVIL, STRUCTURAL CONSUi_ fANfS Page No. 3 Job No. 135229-1 7.2.3 Transitions To limit transitional movement, we anticipate new foundations will extend to recompacted fill material. In consideration of the proposed pad cut-fill transitions, additional undercuts may be necessary, depending on the final building layout. Undercut depths should be based upon maximum depth of fill onsite, and should be approximately one half the maximum fill depth with a minimum depth of three feet. RemovZ1ls for future buildings should extend a minimum of 5 feet beyond the footprint of the proposed structures and settlement sensitive improvements. Where this condition cannot be met it should be reviewed by the Engineering Design Group on a case by case basis. Removal depths should be visually verified by a representative of our firm prior to the placement offill. 7.2.4 Fills All fill should be brought to +2% of optimum moisture content and re-compacted to at least 90 per-cent relative compaction (based on ASTM 01557). Excavated sandy materials are suitable for re-use as fill material during fill operations, provided they are cleaned of debris and oversize material in excess of 6 inches in diameter (oversized material is not anticipated to be of significant concern) and are free of contamination. Fills should generally be placed in lifts not exceeding 6-8 inches in thickness. If the import of soil is planned, soils should have a low potential for expansion (El<50), free of debris and organic matter. Prior to importing soils should be visually observed, sampled and tested at the borrow pit area to evaluate soil suitability as fill. 7 .2.5 Slopes Permanent slopes may be cut to a face ratio of 2:1 (horizontal to vertical). Permanent fill slopes shall be placed at a maximum 2:1 slope face ratio. All temporary cut slopes shall be excavated in accordance with OSHA requirements and shall not undermine adjacent property or structures without proper shoring. Subsequent to grading, planting or other acceptable cover should be provided to increase the stability of slopes, especially during the rainy season (October thru April). FOUNDATIONS The following design parameters may be utilized for new foundations founded on competent material. 7.2.6 Footings bearing in competent sandstone material or recompacted fill material may be designed utilizing maximum allowable soils pressure of 2,000 psf. 7.2.7 Seismic Design Parameters Site Class D Spectral Response Coefficients 5Ms (g) 1.248 Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEERING DESIGN GROUP GEOTECHNICAL. CIVIL. SlRUCl URAL CONSUL 1 ANIS Page No. 4 Job No. 135229-1 Spectral Response Coefficients SMl (g) 0.719 Sos (g) 0.832 SDl (g) 0.479 7 .2 .8 Bearing values may be increased by 33% when considering wind, seismic, or other short duration loadings. 7.2.9 The parameters in the table below should be used as a minimum for designing new footing width and depth below lowest adjacent grade. Footing depths to be confirmed in the field by a representative of Engineering Design Group prior to the placement of form boards, steel and removal of excavation equipment. No. of Floors Supported Minimum Footing Width *Minimum Footing Depth Below Lowest Adjacent Grade 1 15 inches 18 inches 2 15 inches 18 inches 3 18 inches 24inches 7.2.10 All footings founded into competent material should be reinforced with a minimum of two #4 bars at the top and two #4 bars at the bottom (3 inches above the ground). For footings over 30 inches in depth, additional reinforcement, and possibly a stemwall system will be necessary, and should be reviewed by project structural engineer prior to construction. 7.2.11 All isolated spread footings should be designed utilizing the above given bearing values and footing depths, and be reinforced with a minimum of #4 bars at 12 inches o.c. in each direction (3 inches above the ground). Isolated spread footings should have a minimum width and depth of 24 inches. 7.2.12 For footings adjacent to slopes a minimum of 10 feet (sandstone material) and horizontal setback in competent material or properly compacted fill should be maintained. All slope setbacks above the oversteepened cut slope at the driveway should be taken based upon a project 2:1 slope from the existing toe. A setback measurement should be taken at the horizontal distance from the bottom of the footing to slope daylight. Where this condition can not be met it should be brought to the attention of the Engineering Design Group for review. 7.2.13 All new buildings shall maintain a minimum of H/2 setback from the toe of the very steep slope along the north side of the property. Any reduction in the horizontal setback shJII based upon a specific review of the site plan and building layout. 7.2.14 All excavations should be performed in general accordance with the contents of this report, applicable codes, OSHA requirements and applicable city and/or county standards. 7.2.15 All foundation subgrade soils and footings shall be pre-moistened to 2% over optimum to a minimum of 18 inches in depth prior to the pouring of concrete. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGIN.EERING Dh'SJGN GROUP GEOTECHNlCAL. C!Vll. S rRUCTURAL CONSUL TAN TS Pdge No. s Job No. 135229-1 7.3 CONCRETE SLABS ON GRADE All new concrete slab on grade floors should be placed on recompacted fill mater·ial shall use the following as the minimum design parameters. 7.3.1 Concrete slabs on grade of the building and drivew.:iy should h;ive a minimum thickness of S inches and should be reinforced with #4 bars at 18 inches o.c. placed at the midpoint of the slab. Slump: Between 3 and 4 inches maximum Aggregate Size: 3/4 -1 inch Non-Moisture Sensitive Areas: Compressive Strength= 2,500 psi minimum. Moisture Sensitive Areas: Water to cement Ratio -0.45 m<lximum Compressive Strength -0 4,500 psi minimum (No special inspection required for water to cement ratio purposes, unless otherwise specified by the structural engineer) Moisture retarding additive in concrete at concrete slab on grade floors and moisture sensitive areas. 7.3.2 In moisture sensitive areas, the slab concrete should have a minimum water to cement (w/c) ratio of 0.45, generally resulting in a compressive strength of approximately 4,500 psi (No special inspection required for water to cement ratio purposes, unless otherwise specified by the structural engineer) as determined by the w/c ratio. This recommendation is intended to achieve a low permeability concrete. 7.3.3 All required fills used to support slabs, should be placed in accordance with the grading section of this report and the attached Appendix B, and compacted to 90 percent Modified Proctor Density, ASTM 0-1557, and as described in the Earthwork section of this report. 7.3.4 A one inch layer of coarse sand material, Sand Equivalent (S. E.) greater than 50 and washed clean of fine materials, should be placed beneath the slab in moisture sensitive areas, above the vapor barrier. There shall be not greater than a ½ inch difference across the sand layer. 7.3.5 In moisture sensitive areas, a vapor barrier layer (15 mil) should be placed below the upper one inch of sand. The vapor barrier shall meet the following minimum requirements: • Permeance of less than 0.01 perm [grains/(ft2 hr in/Hg)] as tested in accordance with ASTM E 1745 Section 7.1. • Strength per ASTM 1745 Class A. • The vapor barrier should extend down the interior edge of the footing excavation a minimum of 6 inches. The vapor barrier should lap a minimum of 8 inches, sealed along all laps with the manufacturer's recommended adhesive. Beneath the vapor barrier a uniform layer of 3 inches of pea gravel is recommended under the slab in order to more uniformly support the slab, help distribute loads to the soils beneath the slab, and act as a capillary break. 7.3.6 Adequate control joints should be installed to control the unavoidable cracking of concrete that takes place when undergoing its natural shrinkage during curing. The control joints should be well located to direct unavoidable slab cracking to areas that are desirable by the designer. 7.3.7 All subgrade soils to receive concrete slabs and flatwork are to be pre-soaked to 2 percent over optimum moisture content to a depth of 18 inches. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGJNEh""'RJNG D.ESJGN GROUP GEOTECHNICAL. CIVIL, STRUCTURAL CONSUL 1 ANIS Page No. 6 Job No. 135229-1 7.3.8 Exterior concrete flatwork and driveway slabs, due to thE-, nc1ture of concrete hydration and minor subgrade soil movement, are subject to normal minor concrete cracking. To minimize expected concrete cracking, the following may be implemented: • Concrete slump should not exceed 4 inches. • Concrete should be poured during "cool" (40 • 65 degrees) weather if possible. If concrete is poured in hotter weather, a set retarding additive should be included in the mix, and the slump kept to a minimum. • • • Concrete subgrade should be pre-soaked prior to the pouring of concrete. The level of pre-soaking should be a minimum of 2% over optimum moisture to a depth of 18 inches. Concrete may be poured with a 10 inch deep thickened edge. Flatwork adjacent to top of a slope should be constructed with a outside footing to attain a minimum of 7 feet distilnce to daylight. Concrete should be constructed with tooled joints or silwcuts (1 inch deep) creating concrete sections no larger than 225 square feet. For sidewalks, the maximum run between joints should not exceed 5 feet. For rectangular shapes of concrete, the ratio of length to width should generally not exceed 0.6 (i.e., 5 h. long by 3 ft. wide). Joints should be cut at expected points of concrete shrinkage (such as male corners), with diagonal reinforcement placed in accordance with industry standards. Isolation joints should be installed at exterior concrete where Drainage adjacent to concrete flatwork should direct water away from the improvement. Concrete subgrade should be sloped and directed to the collective drainage system, such that water is not trapped below the flatwork. The recommendations set forth herein are intended to reduce cosmetic nuisance cracking. The project concrete contractor is ultimately responsible for concrete quality and performance, and should pursue a cost-benefit analysis of these recommendations, and other options available in the industry, prior to the pouring of concrete. 7.4 RETAINING WALLS New site and/or building retaining walls up to 6 feet may be designed and constructed in accordance with the following recommendations and minimum design parameters. 7.4.1 Retaining wall footings should be designed in accordance with the allowable bearing criteria given in the "Foundations" section of this report, and should maintain minimum footing depths outlined in "Foundations" section of this report. It is anticipated that all retaining wall footings will be placed on recompacted fill material or competent sandstone. Where cut-fill transitions may occur footings may be deepened to competent material and alternative detailing may be provided by the Engineering Design Group on a case by case basis. 7.4.2 In moisture sensitive areas (i.e. interior living space where vapor emission is a concern), we recommend any building retaining walls be designed as poured in place concrete in lieu of masonry to limit vapor emissions. 7 .4.3 Unrestrained cantilever retaining walls should be designed using an active equivalent fluid pressure of 35 pcf. This assumes that granular, free draining material with very low potential for expansion (E.I. <20) will be used for backfill, and that the backfill surface will be level. Where soil with potential for expansion is not low (E./. >SO) a new active fluid pressure will be provided by the project soils engineer. Backfill materials should be considered prior to the design of the retaining walls to ensure accurate detailing. We anticipate onsite material will be utilized as retaining wall backfill. For sloping backfill, the following Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEERING DESIGN GROUP GEOTECHNICAL. CIVIL, SIRUCl UR/\l CONSUi.TAN rs Page No. 7 Job No. 135229-1 ,,,...., """' parameters may be utilized: Backfill Sloping Condition Active Fluid Pressure 2:15/ope 1.5:15/ope 50 pcf 65 pcf Any other surcharge loadings shall be cJnalyzed in addition to llw above values. 7.4.4 If the tops of retaining walls are restrained from movement, they should be designed for an uniform at- rest soil pressure of 65 psf. 7.4.5 Retaining walls shall be designed for additional lateral forces due to earthquake, where required by code, utilizing the following design parameters. • Yielding Walls== PE== (3/8) kAE(Y) H2 -applied at il distance of 0.6 times the height (H) of the wall above the base • Horizontal ground acceleration value kH = 0.25g. • Where non-yielding retaining walls are proposed, the specific conditions should be brought to the attention of Engineering Design Group for alternative design values. • The above design parameters assume unsaturated conditions. Retaining wall designs for sites with a hydrostatic pressure influence (i.e groundwater within depth of retaining wall or waterfront conditions) will require special design considerations and should be brought to the attention of Engineering Design Group. 7.4.6 Passive soil resistance may be calculated using an equivalent fluid pressure of 300 pcf. This value assumes that the soil being utilized to resist passive pressures, extends horizontally 2.5 times the height of the passive pressure wedge of the soil. Where the horizontal distance of the available passive pressure wedge is less than 2.5 times the height of the soil, the passive pressure value must be reduced by the percent reduction in available horizontal length. 7.4. 7 A coefficient of friction of 0.33 between the soil and concrete footings may be utilized to resist lateral loads in addition to the passive earth pressures above. 7.4.8 Retaining walls should be braced and monitored during compaction. If this cannot be accomplished, the compactive effort should be included as a surcharge load when designing the wall. 7.4.9 All walls shall be provided with adequate back drainage to relieve hydrostatic pressure, and be designed in accordance with the minimum standards contained in the "Retaining Wall Drainage Detail", Appendix D. The waterproofing elements shown on our details are minimums, and are intended to be supplemented by the waterproofing consultant and/or architect. The recommendations should be reviewed in consideration of proposed finishes and usage, especially at basement levels, performance expectations and budget. If deemed necessary by the project owner, based on the above analysis, and waterproofing systems can be upgraded to include slab under drains and enhanced waterproofing elements. 7.4.10 Retaining wall backfill should be placed and compacted in accordance with the "Earthwork" section of this report. Backfill shall consist of soil with a very low expansion potential, granular, free draining material. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEh1UNG DESIGN GROUP GEOTECHNICAL. CIV!l, S ! HUC:TUHAL CON~~UL 1 AN 1 S Page No. 8 Jou No. 135229-1 7.5 SURFACE DRAINAGE ,,......, \...., """"" ....,, Adequate drainage precautions at this site are imperative and will play a critical role on the future performance or the dwelling and improvements. Under no circumstances should water be allowed to pond against or adjiJcent to foundation walls, or tops of slopes. The ground surface surrounding proposed improvements should be relatively impervious in nature, and slope to drain away from the strncture in all directions, with a minimum slope or 2% for a horizontal distance of 7 feet (where possible). Area drains or surface swales should then be provided to accommodate runoff and avoid any ponding of water. Any French drains, backdrains and/or slab underdrains shall not be tied to surface area drain systems. Roof gutters and downspouts shall be installed on the new and existing structures and tightlined to the area drain system. All drains should be kept clean and unclogged, including gutters and downspouts. Area drains should be kept free of debris to allow for proper drainage. Over watering can adversely affect site improvements and cause perched groundwater conditions. Irrigation should be limited to only the amount necessary to sustain plant life. Low flow irrigation devices as well as automatic rain shut-off devices should be installed to reduce over watering. Irrigation practices and maintenance of irrigation and drainage systems are an important component to the performance of on site improvements. During periods of heavy rain, the performance of all drainage systems should be inspected. Problems such as gullying or ponding should be corrected as soon as possible. Any leakage from sources such as water lines should also be repaired as soon as possible. In addition, irrigation of planter areas, lawns, or other vegetation, located adjacent to the foundation or exterior flat work improvements, should be strictly controlled or avoided. 8 CONSTRUCTION OBSERVATION AND TESTING The recommendations provided in this report are based on subsurface conditions disclosed by the investigation and our general experience in the project area. Interpolated subsurface conditions should be verified in the field during construction. The following items shall be conducted prior/during construction by a representative of Engineering Design Group in order to verify compliance with the geotechnical and civil engineering recommendations provided herein, as applicable. The project structural and geotechnical engineers may upgrade any condition as deemed necessary during the development of the proposed improvement(s). 8.1 Review of final approved grading and structural plans prior to the start of work for compliance with geotechnical recommendations. 8.2 Attendance of a pre-grade/construction meeting prior to the start of work. 8.3 Observation of subgrade, keysways and excavation bottoms. 8.4 Testing of any fill placed, including retaining wall backfill and utility trenches. 8.5 Observation of footing excavations prior to steel placement and removal of excavation equipment. 8.6 Field observation of any "field change" condition involving soils. 8.7 Walk through of final drainage detailing prior to final approval. The project soils engineer may at their discretion deepen footings or locally rt)COmmend additional steel reinforcement to upgrade any condition as deemed necessary during site observations. Engineering Design Group shall, prior to the issuance of the certificate of occupancy, issue in writing that the above inspections have been Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEERING DESIGN GROUP GEOTECHNICAL, CIVIL STRUCfURAL CONSULTANTS Page No. 9 Job No. 135229·1 conducted by a representative of their firm, and the design considerations of the project soils report have been met. The field inspection protocol specified herein is consider·ed the rninirnurn necessary for Engineering Design Group to have exercised "due diligence" in the soils engineering design aspect of this building. Engineering Design Group assumes no liability for structures constructed utilizing this report not meeting this protocol. Before commencement of grading the Engineering Design Group will require a separate contract for quality control observation and testing. Engineering Design Group requires a minimum of 48 hours notice to mobilize onsite for field observation and testing. 9 MISCELLANEOUS It must be noted that no structure or slab should be expected to remc1in totally free of cracks and minor signs of cosmetic distress. The flexible nature of wood and steel structures allows them to respond to movements resulting from minor unavoidable settlement of fill or natural soils, the swelling of clay soils, or the motions induced from seismic activity. All of the above can induce movement that frequently results in cosmetic cracking of brittle wall surfaces, such as stucco or interior plaster or interior brittle slab finishes. Data for this report was derived from surface observations at the site, knowledge of local conditions, and a visual observation of the soils exposed in the exploratory borings. The recommendations in this report are based on our experience in conjunction with the limited soils exposed at this site and neighboring sites. We believe that this information gives an acceptable degree of reliability for anticipc1ting the behavior of the proposed structure; however, our recommendations are professional opinions and cannot control nature, nor can they assure the soils profiles beneath or adjacent to those observed. Therefore, no warranties of the accuracy of these recommendations, beyond the limits of the obtained data, is herein expressed or implied. This report is based on the investigation at the described site and on the specific anticipated construction as stated herein. If either of these conditions is changed, the results would also most likely change. Man-made or natural changes in the conditions of a property can occur over a period of time. In addition, changes in requirements due to state of the art knowledge and/or legislation, are rapidly occurring. As a result, the findings of this report may become invalid due to these changes. Therefore, this report for the specific site, is subject to review and not considered valid after a period of one year, or if conditions as stated above are altered. It is the responsibility of the owner or his representative to ensure that the information in this report be incorporated into the plans and/or specifications and construction of the project. It is advisable that a contractor familiar with construction details typically used to deal with the local subsoil and seismic conditions, be retained to build the structure. If you have any questions regarding this report, or if we can be of further service, please do not hesitate to contact us. We hope the report provides you with necessary information to continue with the development of the project. Hall Development 4400 Park Drive, Carlsbad, by the Sea, California ENGINEERING DESIGN GROUP GEOTECHNICAL, CIVIL, STRUCTURAL CONSULTANTS Page No. 10 Job No. 135229-1