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HomeMy WebLinkAboutCT 81-10; Carlsbad Research Center Lot 11; Soils Report; 1990-03-27-” Dkw 313-2 GEOTECHNICAL EXPLORATION, INC. SOIL & FOUNDATION ENGINEERING l GROUNDWATER HAZARDOUS MATERIALS MANAGEMENT l ENGINEERING GEOLOGY - - r- I - 7 - 27 March 1990 Mr. Mark Singerman 3760 Convov Street. Suite 332 Job No. 88-5405 San Diego,~‘CA 92ill - R~ ~ Subject: Soil Investiaation and Site Plan Review Lot 11 - Carlsbad Research Center Southwest Corner of Priestly Drive and Rutherford Road Carlsbad, California Dear Mr. Singerman: In accordance with your request, Ceotechnical Exploration, Inc. has reviewed our “Report of Soil Investigation,” dated December 1, 1988 for the subject site and a prellmlnary site plan, dated March 9, 1990. It is our understanding that development plans have not changed significantly since the issuance of our initial report and that the site is being developed to receive ~four, single-story, office and industrial multi-tenant buildings with adjacent parking and other associated improvements. - - - - c I The site has not been significantly altered since our initial investigation, however, as indicated in our report, the upper 2 feet of ,.._. ,._ ~- .,-..,, ._ ^ _ fill soils have become dried, cracked and loose since Its placement (due -____ ~_-,--~~~-~ .---~.-. .,... __ _... ,,_ to exposure to the elements) and will require removal and recompaction prior to any site development. -_- Based upon our review of the preliminary site plan, it is our opinion that the original report is still considered valid for the proposed development. In addition, at your request, we have provided a preliminary pavement design section for the parking and driveway areas. ENGiNEERIN DEPT. LlBRARY City of Carlsbad 207.5 Las Palmas Drive Carlsbad, CA 92009-4859 -..-A ~n~r.c rrmcrr _ PANI n,cr_n rt,, IF~DNIA 0~74 . 16401 SA0.7377 . FAX: 161915AQ-16OA ’ b Carlsbad Research Center Carlsbad. California - - - r r ?- r Job No. 88-5405 Page 2 Preliminary Pavement Design Criteria Contemporary pavement section design methods require compaction of the upper 12 inches of subgrade soils (natural ground or compacted fill) to 90 percent of Maximum Dry Density, and all base materials to at least 95 percent of Maximum Dry Density. We therefore recommend that the upper 12 inches of subgrade soils, all fill, and all base materials beneath the proposed, driveway and parking area pavements be compacted to these standards. This recommendation also applies to the upper soils in backfilled trenches or behind retaining walls which will support pavement sections. Our Ceotechnical Engineer has assigned an R-value of 5 based on our knowledge and experience with the highly expansive on-site soils. Based on a traffic index of 4.5 for parking areas and 6.0 for driveways ahd heavy traffic areas, we have developed the preliminary pavement section alternatives Guide for California Parking Areas Driveways in accordance with the “Structural Section Design Cities and Counties” procedures. Asphalt Processed MISC. Base Concrete [Class II Aqgreqate Base) 3 inches 8 inches 3 inches 14 inches or 4 inches 12 inches Since pavement sections depend largely upon the final subgrade soil conditions exposed after grading, R-value tests should be taken at the L completion of reaching subgrade elevation, to determine if the on-site subgrade rolls might allow for a lighter pavement sectlon than the preliminary section given. r- ‘, Carlsbad Research Center Carlsbad, California Job No. 88-5405 Page 3 Positive drainage and appropriate erosion control measures must be maintained on the site at all times. Particular care should be taken to prevent surface runoff waters from ponding on asphalt parking and driveway areas. Should you have any questions concerning our report, please feel free to contact the Proj,ect Coordinator. Reference to our Job No. 88-5405 will help to expedite a response to your inquiry. Respectfully submitted, CEDTECHNICAL EXPLORATION. INC. Jai&e A. Cerros, R.C.E. 34422lC.E. 2007 JKHlJACllp REPORT OF SOIL INVESTIGATION Proposed Commercial and Industrial Development Lots 6 and 11 - Carlsbad Research Center Southwest Corner of Priestly Drive and Rutherford Road Carlsbad, California - c Job No. 88-5405 01 .December 1988 Prepared for: Mr. Bu&-el Magwsson Bay Development Corporation GEOTECHNICAL EXPiOiATIk. il;. ~. SOIL & FOUNDATION ENGINEERING . GROUNDWATER HAZARDOUS MATERIALS MANAGEMEM . ENGINEERING GEOLOGY - - - - - - 01 December 1988 Mr. Burrei Magnusson BAY DEVELOPMENT CORPORATION 19600 Fairchild, Suite 200 Irvine, CA 92715 Job No. 88-5405 Subject: Report of Sol1 Investlaatlon Commercial and Industrial Development Lots 6 and 11 .- Carlsbad Research Center Southwest Corner of Priestly Drive and Rutherford Road Carisbad, California Dear Mr. Magnusson: In accordance with your request, Ceotechnlcal Exploration, Inc. has performed an investigation of the soil conditions at the two subject lots. The field work was performed on November 1, 1988, by our Field Geologist. It is our understanding that the previously graded lots are being developed to receive a total of 6 office and industrial multi-tenant buildings. The structures are to be a maximum of 2 stories in height and will be constructed of standard type building materials. Our Investigation revealed that the lots are underlaln by dense formational materials and up to 17 feet of highly expansive, compacted fill soils that should provide adequate bearing strength for the proposed structures. In our opinion, if the conclusions and recommendations presented in this report are implemented during site preparation, the lots should be suited for the proposed development. The work performed and recommendations presented in this report are the result of an investigation and analysis which meets the contemporary standard of care in our profession within the San Diego County area. This opportunity to be of service is sincerely appreciated. Should you have any questions concerning the following report, ‘please contact our office. Reference to our Job No. 88-5405 will help to expedite a response to your Inquiry. Respectfully submitted, LDRllp 7420 TRADE STREET l SAN DIEGD. CALIFORNIA 92121 l (619) 549-7222 TABLE OF CONTENTS - - -, I.’ SCOPE OF WORK II. BACKGROUND INFORMATION Ill. SITE DESCRIPTION IV. FIELD INVESTIGATION V. DESCRIPTION OF SOILS VI. GROUNDWATER AND DRAINAGE CONDITIONS VII. LABORATORY TESTS 6 SOIL INFORMATION VIII. CONCLUSIONS AND RECOMMENDATIONS IX. GRADING NOTES X. LIMITATIONS FIGURES I. II a-i. Ill a-e. IV. Plot Plan Boring Logs Laboratory Test Results Foundation Requirements Near Slopes / APPENDICES -z - A. :: Unified Soil Classification Chart General Earthwork Specifications General Discussion of Expansive Soil Behavior PAGE 1 2 2 3 4 5 5 7 16 17 - REPORT OF SOIL INVESTIGATION Proposed Commercial and l,ndustrial Developmeni~ _.- Lots 6 and 11 - Carlsbad Research Center ~~ Southwest Corner of Priestly Drive and Rutherford Road Carlsbad, California Job No. BB-S405 The following report presents the findlngs and recommendations Gemtechnical Exploration, Inc. for the subject project. of I. SCOPE OF WORK It is our understanding, based on communications with Ms. Dennie Smith and review of site plans provided by Smith Consulting Architects, that the lots have been previously graded and are Intended for the construction of a total of 6 office and industrial multi-tenant buildings with associated improvements and parklng areas. With the above in mind, the scope of work is brlefly outlined as follows: I. 6. Identify and classify the surface and subsurface soils to depths, in conformance with the Unified Soil Classification System (refer to Appendix Al. Evaluate the existing fill material. Recommend an allowable bearing pressure for the existing soils. Recommend site preparatlon procedures. Estimate the anticipated settlement of the natural-ground soils, as well as any compacted fill soils, under the anticipated structural loads. Provide foundation design Information and the active and passive earth pressures to be utiiized in design of any retaining walls and foundation structures. -, A i - r Carlsbad Research Center ’ Carlsbad, California Job No. 66-5405 - Page 2 -:=’ II. BACKGROUND INFORMATION During the course of our investigation, we discussed the project with Ms. Dennie Smith and reviewed the following documents concerning the subject lots. 1. 2. 3. 4. San Diego Soils Engineering, Inc., April 21, 1982, As-graded Geotechnicai Report, Rough Grading Completed -- Carlsbad Research Center, Phase I, Carlsbad, California; Job No. SD1144- 10. Woodward-Clyde Consultants, April 27, 1961, Preliminary Soil and Geologic Investigation -- Carisbad Research Center, Carlsbad, California. Woodward-Clyde Consultants, August 17. 1981, Additional Studies, Carlsbad Research Center, Phase I, Carlsbad, California. Woodward-Clyde Consultants, September 3, 1981, Addendum to Additional Studies, Carlsbad Research Center, Phase I, Carlsbad, California. Ill. SITE DESCRIPTION The property is known as: Lots 6 and 11 of Carisbad Research Center, Tract 81-10 in the City of Carlsbad, State of California. The two previously graded lots consist of approximately 12.0 acres and are located at the southwest corner of Priestly Drive and Rutherford Road in the City of Carlsbad. The property is bordered on the - r- Carlsbad Research Center Carlsbad, California Job No. 88-5405 7.~ Page3 --~ northeast by Priestly Drive, on the northwest by Faraday Avenue, on the southeast by Rutherford Road and on the southwest by developed commercial and industrial properties. There were no structures on either lot at the time of our investigation. Vegetation on the lots consist primarily of native weeds and grasses with ornamental landscaping bordering the streets. The property has been graded into two relatively level lots with a 3 to 5 foot high fill slope separating the two. Lot 6 slopes gently to the northwest with approximate elevations ranging from 309 feet above Mean Sea Level (MSL) to 300 feet MSL. Lot 11 slopes gently to the south with approximate elevations ranging from 307 feet MSL to 298 feet MSL. Survey information was obtained from grading plans prepared by Rick Engineering Company, dated September 23, 1981. IV. FIELD INVESTIGATION Nine test borings were placed on the lots, specifically in areas where the structures and Improvements may be located and where representative soil conditions were expected. The borings were located in the field by referring to site. plans, prepared by Smith Consulting Architects, dated October 26. and 28. 1988. The borings were observed and logged by our Field Geologist, and samples were taken of the predominant soils throughout the field operation. Boring logs have been prepared on the basis of our observations and the results have been summarized on Figure No. Ii. The predominant soils have been classified in conformance with the Unified Soil Classification System (refer to Appendix Al. In-place samples were obtained by driving a )-inch outside-diameter (0.0.) by Z-3/8-inch inside-diameter (I.D.) split-tube sampler a distance of 12 inches. Also, the Standard Penetration Test was - Carlsbad~ Research Center Carlsbad, California ::Job No. 88-5405 _ Page 4 performed by using a 140-pound weight falling 30 inches to drive a 2- inch O.D. by l-3/8-inch I.D. sampler tube a distance of 12 inches. The number of blows required to drive the sampler the given distance was recorded for use in density determination. The following chart provides an in-house correlation between the number of blows and the relative density of the soil for the Standard Penetratlon Test and the 3- inch sampler. Density Soil - Designation Sand and Silt Very loose Loose Medium Dense Very dense Clay Very soft Soft Firm Stiff Very stiff Hard Very hard 2-inch O.D. Sampler Blows/Foot 3-inch O.D. Sampler Blows/Foot O-4 S-10 11-30 31-50 Over 50 o-7 8-20 21-53 54-98 Over 98 o-2 o-2 3-4 3-4 5-8 5-9 9-15 lo-18 16-30 19-45 31-60 46-90 Over 60 Over 90 V. DESCRIPTION OF SOILS The lots, in general, are overlain with a varying thickness of compacted fill soils reaching a maximum thickness of approximately 17 feet in the southern portion of lot 11 (B-4). The fills are medium dense to dense and consist of mottled, yellow-tan and gray-brown, sandy silt with clay and dark gray-brown, sandy clay with rock fragments and siltstone chunks. These soils are considered to have a high expansion potentlal and low consolidation potential. On a portion of lot 11, the fill soils are underlain by approximately 2 to 3 feet of alluvium consisting of gray-brown, silty fine sand. The alluvium was - - Carisbad Research Center Carisbad, California Job No. 88-5405 Pago 5 ~ only encountered in boring No. 5 at what appears to be the bottom of a canyon fill. The entire site is underlain by dense, silty and sandy, formational materials, which are considered to have a high expansion potential but have good bearing-strength characteristics. VI. GROUNDWATER AND DRAINAGE CONDITIONS Groundwater was encountered at 21 feet below existing grade of Lot 11 during the course of our field investigation. At this depth we do not expect the groundwater to cause significant problems, if the property is : developed as presently designed. It should be kept In mind, however, that any required additional grading operations may change surface drainage patterns and/or reduce permeabilities due to the densification of compacted soils. Such changes of surface and subsurface hydrologic conditions, plus irrigation of landscaping or significant increases ‘in rainfall, may result in the appearance of minor amounts of surface or near-surface water at locations where none existed previously. The damage from such water is expected to be minor and cosmetic in nature, if good positive drainage is implemented at the completion of construction. Corrective action should be taken on a site-specific basis if, and when, it becomes necessary. VII. LABORATORY TESTS AND SOIL INFORMATION Laboratory tests were performed on the disturbed and relatively undisturbed soil samples In order to evaluate their physical and mechanical properties and their ability to support the proposed structure. The following tests were conducted on the’ sampled soils: 1. Moisture/Density Relations (ASTM 01557-78, Method Al 2. Moisture Content (ASTM D2216-80) 3. Penetration Test and Split-Barrel Sampling (ASTM D1586-84) 4. Atterberg Limits (ASTM D4318-84) 5. Expansion Tests (UBC Method 29-2) 6. Consolidation Tests (ASTM 02435-80) 7. Direct Shear Tests (ASTM D3080-78) -. Carlsbad Research Center ’ Carlsbad, California - Job No. 88-5405 Page 6 The relationship between the moisture and density of undisturbed soil samples gives qualitative information regarding soil strength characteristics and soil conditions to be anticipated during any future grading operation. The Atterberg Limit tests were used to aid in the classification of the soils according to the Unified Soil Classification System. The expansion potential of clayey soils was determined utilising the Uniform Building Code Test Method for Expansive Soils (UBC Standard No. 29-2). In accordance with the UBC (Table 29-C), expansive soils are classified as follows: - - Expansion Index Potential Expanslon 0 to 20 Very Low 21 to 50 Low 51 to 90 Medium 91 to 130 . High Above 130 Very High According to the UBC Test Method for Expansive Soils, the clayey soils tested have a high expansion ,potential, with an expansion index ranging from 120 to 127. Consolidatlon tests were performed on relatively undisturbed samples of compacted fill soils. The soils were contained in l-inch-high brass rings and loaded into a consolidometer. The specimens were subjected to increased loads and the resulting consolidations noted. The consolidation test aids in determlning anticipated settlements of the fill soils under the proposed buildings loads and the weight of any overburden fill soils. Car&bad Research Center ’ Carlsbad, California Job ~No. 88-5485 I Page 7 Direct shear tests were performed upon relatively undisturbed samples in order to measure the roll strength and supporting capacity of the compacted fill. The shear tests were performed with a constant strain direct shear machine. Specimens to be tested were saturated and then sheared under various normal loads without appreciable drainage of the samples. Based upon the above laboratory test data, observations of the primary soil types on the project, and our previous experience wlth laboratory testing of similar soils, our Geotechnical Engineer has assigned conservative values for friction angle cohesion to those soils which will have significant lateral support or bearing functions on the project. These values are presented in Figure No. Ill and have been utilized in recommending the allowable bearing value as well as the active and passive earth pressures for wall and footing designs. VIII. CONCLUSIONS AND RECOMkENDATIONS The following conclusions and recommendations are based upon the practical field investigation conducted by our firm, and resulting laboratory tests, in conjunction with our knowledge and experience with the soils in this area of the City of Carlsbad. Geotechnical Exploratim. Inc. reviewed the “As-graded Geotechnical Report - Rough Grading Completed,” dated April 21, 1981, prepared by San Diego Soils Engineering, Inc. Based on our findings and review, it appears that site preparation and fill compaction was performed in accordance with the local industry standards. Our investigation revealed the lots are underlain by dense formatlonal materials and up to 17 feet of compacted fill soils. Lot 6 is underlain with 1 foot to 11 feet of fill and lot 11 Is underlain by 6 to 17 feet of fill. A daylight line between cut and fill, as indicated on the original -.~.- ^, ,_-~__-,~, grading plan, is shown on Figure No. I. i’ Carisbad Research Center Job No. 88-5405 Carlsbad, California Page 8 - - - The fill soils were found to be generally well compacted and at or above optimum moisture. The upper 2 feet of fill soils, however, have become dried, cracked and loose since its placement (due to exposure to the elements) and should be reworked prior to site development. Although __I__x,- .,._x a few of the in-place density tests taken on samples of the encountered artificial fill material yielded results of less than 90 percent of Maximum Dry Density in accordance with A.S.T.M. 1557-78 (90 percent represents the minimum industry standard for compaction of artificial fill soils). our qualitative assessment of the fill is that it was generally well compacted. Based upon results of the Standard Penetration Test performed during the field investigation, the “blow counts” indicate medium dense fill soils and corroborates the results of the retrleved density samples. For details and laboratory test results, refer to Figure Nos. II, Ill and IV. The prevailing soils encountered on the subject site are highly expansive, apparently well-compacted fill soils. it Is our opinlon that these soils should provide adequate bearing strength for the proposed structures, provided that the 2 feet of loose surface soils are removed _~ ,__.- -. and recompacted as part of the site preparation and that foundations ~.-.. -.___ --.- _~__ _~. are sufficiently reinforced for the exson forces of the bearing soils. Drainage should be well controlled at all times to limit the effects of water on the expansive soil (refer to Appendix C of this report for a more in depth discussion of expansive soils). As part of our soil investigation, Geotechnlcal Exploration, Inc. performed a cursory hazardous materials evaluation for lots 6 and 11. This evaluation included a review of records at the Hazardous Materials Management Division of the County of San Diego Health Department. We found no information regarding the storage or disposal of hazardous materials at the subject lots. Also, during our soil investigation, we performed limited soil testing in order to determine if hazardous materials are detectable in the soils. The results of a standard laboratory analysis for contaminated soil yielded levels well below the allowable limits (see Figure No . ~IleJ. Carlsbad Research Center Carlsbad, Caiifornla A. 1. - .- 2. 3. 4. 5. 1 Job No. 88-5495 Page 9 Preparation of Solls for Slte Development Any existing debris and vegetation observed on the lots must be removed prior to the preparation of building pads and/or areas to receive structural improvements and be properly disposed of. To provide a uniform soil base for the proposed structures, improvements and pavement, the existinee and desiccated __~..., ,.~,., surface soils shall be excavated to a depth’of at least 2 feet, or .“.. ,_ .I. ,L .- --_ _. -...,_ I. . - _..__-_. ~.,~ ~---- ~.. ..~.~ as per the direction of our field technician. The excavated soils shall be cleaned of any debris and deleterious materials and watered to approximately 3 to 5 percent above optimum moisture .- _.-.__.-- ---.-* .~... _ content. The bottom of the excavation shall be scarified moisture conditioned similarly and compacted to at least 90 percent of --.._ maximum dry density. The properly prepared fill soils should be placed in layers not exceeding 8 inches in thickness, and be compacted to at least 90 percent of Maximum Dry Density (A.S.T.M. 01557-781. Soils shall not be compacted over 92 percent, since the higher the denslty the higher the expansion potentlal. No uncontrolled fill soils shall remain on the lots after completion of any future site work. In the event that temporary ramps or pads are constructed of uncontrolled fill soils during the grading operation, the loose fill soils shall be removed and/or recompacted prior to completion of the grading operation. Any buried objects which might be discovered on the lots shall be removed and the resulting excavation be properly backfilled with approved on-site or imported fill soils, and shall then be compacted to et least 90 percent of Maximum Dry Density. Any backfill soils placed in utility trenches or behind retaining wails which support structures and other improvements (such as patios, sidewalks, driveways, pavements, etc.1 shall be compacted to at least 90 percent of Maximum Dry Density. Carlrbad Research Center Carlsbad, California Job No. 66-5465 Page 16 - - .- - 0. Design Parameters for Foundations and Retaining Walls 6. The recommended allowable bearing value for design of foundations for the proposed structures is 3.000 pounds per square foot. This load-bearing value may be utllired in the design of continuous foundations and spread footings when founded a minlmum of 30 inches into the firm natural ground or compacted fill, measured from the lowest adjacent grade at the time of foundation construc- tion. This load-bearing value may be Increased one-third for design loads that include wind or seismic analysis. If imported soils are required to bring the site to grade, the imported soils should be obtained from an approved off-site borrow area. We have recommended 30-inch-deep footings to provide an added moisture barrier around the perimeter of the structures and also to help accommodate the anticipated deflections due to possible differential settlement caused by the varlable thickness of fill under the structures and the typical soil he&e experienced when constructing on highly expansive soil. Based on our laboratory test results, and our experience with the soil types on the subject site, the rolls should experience differential settlement in the, magnitude of less than 1 inch In 25 feet under a structural load of 3,000 pounds per square foot. 7. Due to the highly expansive nature of the on-site soils, we recommend that all conventional footings and slabs contain at least -- _.-__.._. .-.,, ~_. .-.---.l_l a nominal amount of reinforcing steel to reduce the separation of cracks, should they occur. ._ ._ _ ,~- .-_.,___. 7.1 A minimum of steel for continuous footings should include at least four No. 5 steel bars continuous, with two bars near the bottom of the footing and two bars near the top. ,- - - - Carlsbad Research Center Carlsbad, California 1.2 Isolated square footings should contain, as a minimum, a grid of No. 5 steel bars on 12-Inch centers, in both directlons, with no less than three bars each way. Job No. 05-5405 Page 11 7.3 Floor slabs should be a minimum of 5 Inches actual ! thickness and be relnforced with at least No. 3 steel bars ---~-, on 15-inch centers, in both directions, placed at midheight _--, in the slab. Slabs should be underlain by a 3-inch-thick p ,,I J’ f ‘,f .* ‘“+ _ layer of clean sand (S.E. = 30 or greater) overlying a 6-mil : .-,-.. - ..-~ ..-_ - .-- -,-- _ ,_ _..,,.- -. .---... - visqueen membrane. ii:.-- .A_- Slab subgrade soil shall be thoroughly moistened prior to placement of the vapor barrier and pouring of concrete. It is recommended that moisture content of subgrade roll for slabs and footings be checked within 48 hours prior to concrete placement to verify that it is at least 3 percent above optimum and has penetrated at least 1 foot below subgrade and foundation bottom level. We recommend the .project Civil/Structural Engineer incor- porate Isolation joints and sawcuts to at least one-fourth the thickness of the slab in any floor designs. The joints and cuts, if properly placed, should reduce the potential for and help control floor .slab cracking. In any cas~eA*cbg of control joints shall not exceed 25 feet between centers. -,.~,_~-- ,I . . . .._.- _._ ,.~ ,I j;;.--.. However, due to a number of reasons (such as base preparation, construction techniques, curing procedures, and normal shrinkage of concrete), some cracking of slabs can still be expected. NOTE: The project Structural Engtneer shall review all reinforcing schedules. The reinforcing ainimums r-- mended herein are not to be construed as structural ’ designs, but merely as minimum safeguards to reduce possible crack separations. The actual reinforcing schedule shall be as per the direction of the Structural Engineer based upon an anticipated differential settlement of less than 1 Inch In 25 feet horizontally. .-j‘ . I Carlsbad Research Center Job No. 66-5465 Car&bad, California Page 12 -. - j - I -/ I - I - I - I I -1 A We recommend that the Structural Englneer consider use of a post- tensioned slab foundatlon due to the highly expansive soil. Such a foundation has typically performed well in similar site conditions. If a post-tensioned slab foundation Is used, we recommend that a perimeter footing extending to at least 24 inches in depth is used. ,. a. As a minimum for protection of on-site improvements, it Is recommended that all nonstructural concrete slabs [such as patios, walkways, etc.) be underlain by at least 3 Inches of clean sand, -..-.---_. include 6 x 6-10110 welded wire mesh at the center of the slab. _.... -*._,~-_-I- and contain adequate isolation joints. It should be noted that standard concrete Improvements may not perform well, due to the expansive soil conditions. As such, each improvement should be designed to tolerate the on-site conditions. The performance of on-site improvements can also be greatly affected by soil base preparation and the quality of construction, and Is therefore the responsibility of the designer and the contractor installing the improvements. Moisture content and compaction of subgrade soils verification for outside improvements Is also recommended. A representative of our firm shall check that within 46 hours prior to _ concrete pouring. C. Retalnlnq Walls 9. The active earth pressure (to be utilised in the design of canti- lever, walls) shall be based on an Equivalent Fluid Weight of 80 pounds per cubic foot (for level backfill only). .-I -j .- / / In the event that a retaining wall is surcharged by sloping backfill, the design active earth pressure shall be based upon laboratory tests of the specific soils at the site of the proposed retaining wall. Ti”“Y,“i,y’ s’;“r” /i q ‘y, p ’ c-4. >.’ ., <> k, 1. - - - ,- - .- - Carlsbad Research Center .: Job No. 88-5405 Carlsbad, California Page 13 10. 11. D. 12. The design pressures presented above are based on utlilzation of an uncontrolled mlxture of soils native to the site in backfill operations. In the event that imported, clean granular fill soils or approved on-site clean sands are utilized as backfill material, this firm should be contacted for possible reduction of design pressures for level backfill, sloping backfill or restrained wall conditions. In the event that a retaining wall Is to be designed for a restrained condition, a uniform pressure equal to 15xH (fifteen tlmes the total height of retained wall, considered in pounds per square foot) shall be considered as acting everywhere on the back of the wall in ecldition to the design Equivalent Fluid Weight, when utiiiring an uncontrolled mixture of existing soils as backfill. The passive earth pressure of the encountered natural-ground soils and compacted fill soils (to be used for design of shallow foundations and footings to resist the lateral forces) shall be based on an Equivalent Fluid Weight of 275 pounds per cubic foot. This passive earth pressure shall only be considered valid for design if the ground adjacent to the foundation structure is essentially level for a distance of at least three times the total depth of the foundation and is properly compacted or dense natural soil. A Coefficient of Friction of 0.35 times the dead load may be used between the bearing soils and concrete fQUndathS, walls, or floor slabs. Site Drainage Considerations Adequate measures shall be taken to properly finish-grade the site after the structures and other Improvements are in place. Drainage waters from this site and adjacent properties are to be directed away from foundations, floor slabs, footings, and slopes, onto the natural drainage direction for this area or into properly - -. Carlsbad Research Center Carlsbad, California : Job No. 88-5405 Page 14 - - - - - designed and approved drainage facilities. Roof gutters and downspouts should be installed on all structures, with runoff I__~ ~~, -__ _.,,_ ~,,. -.- 1.~. ..., .-.. ~._ ._I _~ ._,._.,,_. I _,__. -,.. -G.--.~- directed a.way from the foundations via, closed drainage lines.> .__.._._. .--.~ --..-... ~.~,. .~ -F.-I..-’ Proper subsurface and surface drainage will help minimize the potential for waters to seek the level of the bearing soils under the foundations, footings, and floor slabs. Failure to observe this recommendation could result in uplift or undermining and differential settlement of the structure of other improvements on the site. We recommend placing a continuous concrete *‘apron” _.- L7;l.jb.L7*. (, ,_ ,,,, _, ;, .._ around the perimeter of all structures and that planter areas and . ..e.--._w_c_ _ .,-_ ~“l.,,~-“., ,. . ~~, planter boxes be kept outside the perimeter apron. _~, .~_ ~._ .-.-z.T4 __ .;_II .,. ,, - - 7 - - - In addition, appropriate erosion-control measures shall be taken at all time during construction to prevent surface runoff waters from entering footing excavations and ponding on finished building pads or pavement areas. Proper backdrains and subdrains shall be installed behind all retaining walls on the subject project. Ceotechniul Exploration. Inc. will assume no Ilability for damage to structures which is attributable to poor drainage. 13. Planter areas and planter boxes shall be sloped to drain away from the foundations, footings, and floor slabs. Planter boxes shall be constructed with a closed bottom and a subsurface drain, Installed in gravel, with the direction of subsurface and surface flow away from the foundations, footings, and floor slabs, to an adequate drainage facility. We strongly suggest that landscaping consist of drought resistant vegetation. Minimal irrigation water and proper drainage of seasonal rainfall waters will minimize volume changes of the near- surface soils. Cartsbad. Research Center Job No. 68-5465 Carlsbad, California Page 15 - E. General Recommendations - 14. Following placement of any concrete floor slabs, sufficient drying time should be allowed prior to placement of floor coverings. Premature placement of floor coverings could result in degradation of adhesive materials and loosening of the flnish-floor materials. ,, -~-~, ,, ~_~_/--e.~. -‘-.“-~---.----L_ -.._-,._ .__,__.. -.~ ,,” . . . 15. Consideration should be given to placement of a PCC slab beneath and in front of any proposed trash enclosures. It has been our ‘.‘.I j experience that most concentrated point loads often occur ‘\, surrounding the trash enclosures from both the trash vehicles and .’ ‘\ ‘. the wheel loads of the trash container, resulting in damage to the ‘\ \yphaltJc pavement. - - - - - 7 16. In order to minimize any work delays at the subject slte during site development, this firm should be contacted 24 hours prior to any need for inspection of footing excavations or field density testing of compacted fill soils. If possible, placement of formwork and steel reinforcement in footing excavations should not occur prior to inspection of the excavations; in the event that our inspection reveals the need for deepening or redesigning foundation structures at any locations, any formwork or steel reinforcement in the affected footing excavation areas would have to be removed prior to correction of the observed problem (I.e., deepening the footing excavation, recompacting soil in the bottom of the excavation, etc.). 17. Contemporary pavement section design methods require compactlon of the upper 6 inches of subgrade soils [natural ground or compacted fill) to 90 percent of Maximum Dry Density, and all base materials to at least 95 percent of Maximum Dry Density. We therefore recommend that the upper 6 inches of subgrade soils and all base materials, beneath the proposed, driveway and parking - - - - Carlsbad Research Center Carlsbad, California : ~, Job No. 68-5405 Page 16 area pavements be compacted to these standards. This recom- mendations also applies to the upper soils in backfilled trenches or behind retaining walls which will support pavement sections. Design of pavement sections was not included within the scope of this report. Pavement sections will depend largely on the sub- grade soil conditions exposed after grading and should be based on R-value test results. These test should be performed after completion of the grading operation. IX. GRADING NOTES Any required grading operations shall be performed in accordance with the General Earthwork Specifications (Appendix 6) and the require- ments of the City of Carlsbad Grading Ordinance. 18. Ceotechnical Exploration. Inc. recommends that we be asked to verify the actual soil conditions revealed during site grading work and footing excavations to be as anticipated in this “Report of Soil Investigation.” In addition, the compaction of any fill soils placed during site grading work must be tested by the soil engineer. It is the responsibility of the grading contractor to comply with the requirements on the grading plans and the local grading ordinance. 19. It is the responsibility of the owner and/or developer to ensure that the recommendations summarized In the report are carried out in the field operations and that our recommendations for design of the project are Incorporated in the building and grading plans. 20. This firm doas not practice or consult in the field of safety engineering. We do not direct the contractor’s operations, and we cannot be responsible for the safety of personnel other than our own on the site; the safety of others is the reasonability of the -- * Carlsbad Research Center Job No. WI-5+05 Carlsbad, Callfornla Page 17 - contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. X. LIMITATIONS Our conclusions and recommendations have been based on all available data obtained from our field investigation and laboratory analysis, as well as our experience with the soils and formation materials located in this area of the City of Carlsbad. Of necessity, we must assume a certain degree of continuity between exploratory excavations and/or natural exposures. It is. therefore, necessary that alf observations. conclusions, and recommendations be verified at the time grading operations begin or when footing excavations are placed. In the event discrepancies are noted, additional recommendations may be issued, if required. - The work performed and recommendations presented herein are the result of an investigation and analysis which meet the contemporary standard of care in our profession within the San Diego County area. No warranty is provided. This report should be considered valid for a period of three (3) years, and is subject to review by our flrm following that time. If signlflcant modifications are made to the building and/or grading plans, especially with respect to the height and location of any proposed structures, this report must be presented to us for Immediate review and possible revision. - - The firm of Cieotechnical Exploration, Inc. shall not be held responslble for changes to the physical condition of the property, such as addition of fill soils or changing drainage patterns, which occur subsequent to issuance of this report. -. . Carlsbad Research Center Job No. 88-5405 Carlsbad, California Page 18 Once again, should any questions arise concerning this report, please feel free to contact the project coordinator. Reference to our Job No. 88-5405 will help to expedite a reply to your inquiries. Respectfully submitted, I rIwr-& Project Hydrogeolog1stIR.C. 4251 eiser, Project Coordinator Jaime A. Ce6os. R.C.E. 34422lCi.E. 2007 WRLIJKHIJACllp - - - - - . ” I : : i : o 0 . ; = : e : : ; z :- : : 0 : : I J--d----‘- I- : : : : : n z : : :: : : . ..’ rn +.. _- --- m-ml-, RUTHERFWD .m *a. ss .n. zo”= : l -o a=*;: n *;*.= : I :;z.: : )..-I a a-m : : ;rno.rnnr mm:f‘O*O* 4 m me =r=n.r,. :::-. . - .:m* :.:::.= :: ,.--. !i! :;- =. -m: .::=-::. rl’I. I_ y :: : ;: IO :: L . :- 0; . : 3; : : i - - - - - EQUIPMENT DIMENSION 6 TYPE OF EXCAVATION DATE LOGGED CME 550 Drill Rig a-inch-diameter boring 11-1-88 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY i306' HSL Not encountered JKH FIELD DESCRIPTION AND I CLASSIFICATION ; DESCRIPTION AND REPARKS A (Grain size. Density. Moisture, Color) I SANDY SILT with some pebbles and siltstone chunks. Medium dense. Damp. Mottled yellow-tan-gray. FILL ------__-------_--_--------------. SANDY CLAY with rock fragments. Very stiff. Damp. Dark gray- brown. SILTY FINE SAND with clay and some pebbles and pieces of grass, I Medium dense. Damp. Dark brown. FILL I SILTSTONE with.some fractures. Dense. Damp. Tan-gray and orange. FORMATION 1 Bottom of Hole @ 16' ';; 4 " 3 Ml ,_, Cl S Ml - a. - 113 118 112 :: Fi z P 9 8( O( - 2 5 2; tl 2: - 3' 2 3 2” 3 j ;; Y > 8 II ,‘I I I, 1 JOB NAME Proposed Commercial Development I P Lot 11. Carlsbadarrh Cent-r WATER TABLE SITE LDCATIDN SW corner of Priestly Drive 6 Rutherford IXI LOOSE BAG SAMPLE El IN-PLACE SAMPLE DRIVE SAMPLE SAND CDNE/F.D.T. Road, Carlsbad, CA JOB NUMBER 1 REVIEWED BY LOG NO. - - - - -. - _. -~ EQUIPMENT DIHENSION 6 TYPE OF EXCAVATION DATE LOGGED 3 CME 550 Drill Rig a-inch-diameter boring 11-1-88 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY i306' MSL *21' JKH ments and siltstone chunks. Medium dense. Hoist. Mottled tan-brown-gray. SANDY CLAY with rock fragments Stiff. Moist. Light gray-tan. some clay binder and silt Medium dense. Moist. Tan-gray-orange. --groundwater encountered JOB NAME Proposed Commercial Development n WATER TABLE SITE LOCATION SW corner of Priestly Drive G Rutherford IXI LOOSE BAG SAMPLE Road, Carlsbad. CA El JOB NUMBER REVIEWED BY LOG No. IN-PLACE SAMPLE 88-5405 DRIVE SAMPLE FIGURE NUMBER B-2 SAND CORE/F.D.T. Ilb 1, - - - - -. - - - SURFACE ELEVATION i301’ MSL GROUNDWATER DEPTH Not Encountered I LOGGED BY JKH 1 l- L I I FIELD DESCRIPTION AND r CLASSIFICATION F s 5 DESCRIPTION AND REMARKS 0 z e x z s (Grain size. Density, Moisture, COlOr) SANDY SILT with some rock frag- ML ments and siltstone chunks. 2 Dense. Damp. Mottled tan-gray- 18.7 110.4 17.6 113 98 75 3” 4 and some rootlets. 11 2” 6 8 10 12 Dense. Damp. Light Bottom of Hole @ 11.5’ 22 2” 15.7 106.7 18.2 112 95 35’ 3” I JOB NAME Proposed Commercial Development a tnt 11. trrlshadr.rrrh rrntpr WATER TABLE SITE LOCATION SW corner of Priestly Drive s Ia LOOSE BAG SAMPLE Rutherford Road, Carlsbad, CA I3 JOB NUMBER REVIEWED BY LOG No. IN-PLACE SAMPLE 88-5405 DRIVE SAMPLE FIGURE NUMBER B-3 SAND CONE/F.O.T,. ~, I Ic CME 550 Drill Rig d-inch-diameter boring EQU'IPMEBT DIMENSION & TYPE OF EXCAVATION DATE LOGGED CME 550 Drill Rig 8-inch-diameter boring 11-l-88 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY I i301' MSL I Not Encountered JKH I a s i I II I I I I I FIELD DESCRIPTION AND CLASSIFICATION : DESCRIPTION AND RENARKS Fir’ (G al" sTze. Density, Moisture, Color) I FILL SANDY CLAY with rock fragments, chunks of wood and grass. Very stiff. Moist. Dark brown-black SANDY CLAY with rock fragments, organics and grass. Firm. Moist. Dark brown-black. FILL SILTSTONE. Dense. Damp. Tan-gray. FORMATION Bottom of Hole 8 21.5' :I ;i :; I: - 0, 7. 6. 103.0 112.8 111.5 7, 4. 113 118 - L ; : s! I1 '6 5 - 34 17 42 17 15 59 - ; ; ;i :: 2: 1” PII 1” ,I# I” I - JOB NAME Proposed Commercial Development i,-,t 11. Carlsbad Research Center v WATER TABLE SITE LOCATION SW corner of Priestly Drive & Rutherford w LOOSE BAG SAMPI -, - - - - - - .- - - , - I / I - I EQUIPMENT DIMENSION 6 TYPE OF EXCAVATION DATE LOGGED CME 550 Drill Rig 8-inch-diameter boring 11-1-88 SURFACE ELEVATION GROUNDWATER DEPTH LOGGED BY i301' HSL Not Encountered JKH FIELD DESCRIPTION AND E CLASSIFICATION E d 2 DESCRIPTION AND REMARKS 2 E z 2 (Grain size, Density, Noisture, COlOr) SANDY SILT with some clay and ML siltstone chunks. Medium dense. Mottled tan-giay-brown. 8.8 105.8 17.6 113 94 41 3" organics and grass. Dark brown-black. SILTY FINE SAND. Hicaceous. Loose. Hoist. Gray-brown-orange 94 39 3" 16 2" 9 3" JOB NAME Proposed Commercial Develo ment Lot 11, Carlsbad Research f enter ‘3 WATER TABLE SITE LOCATION SW Corner of Priestly Dr. S Rutherford IXI Rd., Carlsbad, CA LOOSE BAG SAMPLE Gl JOB NUMBER REVIEWED BY LOG No. IN-PLACE SANPLE 88-5405 DRIVE SAMPLE B-5 FIGURE NUMBER SAND CONE/F.D.T. Ile -. - - - - - c - - e/-__., EQUiPMENT CME 550 Drill Rig SURFACE ELEVATION i307' MSL DIMENSION 6 TYPE OF EXCAVATION DATE LOGGED a-inch-diameter boring 11-1-88 GROIJNDUATER DEPTH LOGGED BY Not Encountered JKH FIELD DESCRIPTION AND I CLASSIFICATION z DESCRIPTION AND REMARKS 5 (&din size. Density. MoIstwe. Color) 1 I SANDY SILT with some clay and siltstone chunks. Medium dense. Damp. Mottled tan-gray-brown. FILL SANDY CLAY with rock-fragments and grass. Stiff. hoist. Dark brown-black FILL .-----------------1---------------. SILTSTONE. Dense. Damp. Tan-gray. FORHATlOh Bottom of Hole @ 11.5’ n MATER TABLE El LOOSE BAG SANPLE Gl IN-PLACE SAMPLE DRIVE SAMPLE SAND CONE/F.D.T. z G v! 1 Ml Cl -. Ml - - 8. 4. 109.1 110.5 7. 4. - 113 118 - c ; = :, 9: 91 - - 2 c- + . 9: 21 Y( - - ~ g; 21 - 32 I4 41 50 - d ii E: ii 5: - 3 II 2" 3 ,I 2" - 1 JOB NAME Proposed Commercial Development Lot 6. Carl-Research Cent-r SITE LOCATION SW corner of Priestly Dr. & Faraday Ave. Carlsbad, CA JOB NUMBER 1 REVIEWED BY LOG NO. - - - - - - I CHE 550 Drill Rig E-inch-diameter boring 11-l-88 SURFACE ELEVATION GROUNDUATER DEPTH LOGGED BY i307’ MSL Not Encountered JKH I FIELD DESCRIPTION I I AND CLASSIFICATION 2 DESCRIPTION AND REMARKS 3 (Grain size. Density. Moisture, Color) FILL SANDY CLAY with rock-fragments, organics and siltstone chunks. Stiff. Hoist. Dark brown. FILL SILTSTONE. Dense. Damp. Tan-gray. FORMATION Bottom of Hole @ 16' I - z: ;j L: -.: - !O. 15. 19. - - - ;; ? + . _ f2 2;: YL 98.3 7. 113 8; 10 I6 116.5 107.1 4. 118 9! 30 18 8, 112 ‘6 75 - - - - - d d az; 5: s: 5’ -2 3 I, 2" 3 II 2" 3 II - JOB NAME Proposed,Commercial Development Lot 6. c arlsbad Research Center v UATER TABLE SITE LOCATION SW Corner of Priestly Dr. S Faraday Ave., Carlsbad. CA El LOOSE BAG SAMPLE IIl JOB NUMBER REVIEYED BY LOG No. IN-PLACE SAMPLE 88-5405 DRIVE SAMPLE B-7 FIGURE NUMBER \ SAND CONE/F.D.T. Ilg - - - - - / - - / I ' EQUIPNENT CNE 550 Drill Rig SURFACE ELEVATION f'402' MSL DIMENSION 6 TYPE OF EXCAVATION FATE LOGGED 1 E-inch-diameter boring 11-1-88 GROUNOUATER DEPTH LOGGED BY Not Encountered JKH FIELD DESCRIPTION AND E CLASSIFICATION E d 5 DESCRIPTION AND RENARKS n. SE% x =, z (Grain size. Density. Moisture, COlOr) , _. :: . . SANDY SILT. Loose. Dry. Tan- ML . :' brown. FILL ' -jj+iriil: SILTSTONE. Dense. Damp. Tan- IIL 21.C 106.9 18.2 112 95 75+ 3 4 so+ 2 6 ,N?B NAME Proposed Commercial Development v Lot 6. Carlsbadch Center UATER TABLE SITE LOCATION SW Corner of Priestly Dr. & Faraday Ave. q Carlsbad, CA LOOSE BAG SANPLE Gl JOB NUMBER REVIEWED BY LOG No. IN-PLACE SAMPLE 88-5405 DRIVE SAMPLE B-8 FIGURE NUMBER SAND CONE/F.D.T. Ilh - - - - I EQUiPMENT DIMENSION 6 TYPE OF EXCAVATION OATE LOGGED 3 CHE 550 Drill Rig E-inch-diameter boring 11-l-88 SURFACE ELEVATION GROUNDUATER OEPTH LOGGED BY *3041 HSL Not Encountered JKH I 1 I FIELD DESCRIPTION AND t: CLASSIFICATION E d 2 DESCRIPTION AND REMARKS L z E z 2 (Grain size. Density. Moisture, Color) , -1 ..i'... : 1; : * SANDY SILT. Loose. Dry. Tan- t4L brown. FILL 2 -*r-l SILTSTONE. Dense. Damp. Tan- ML 1 way. 28 2” 4- FORMAT I ON 6 I- 50+ 2” Bottom of Hole @ 6’ JOB NAME vroposed Lommertlal Development Lot 6, Carlsbad Research Center ‘3 MATER TABLE SITE LOCATION SW Corner of Priestly Dr. & Faraday Ave., q Carlsbad, CA LOOSE BAG SAMPLE Q JOB NUMBER REVIEYED BY LOG No. IN-PLACE SAMPLE 88-5405 DRIVE SAMPLE B-9 FIGURE NUHBER SAND CONE/F.D.T. I I i 1 - - - - - - - Gravel Sand Fines %uL Fl"l 5111 CllY U.S. sland.r* siere 11x1 ~~~.~.I - LABORATORY SOIL DATA SUMMARY 140 100 SPAIN DINETEi. Y 90 SPECIFIC GRAVITY ZERO AIR VOIDS CURVES BOL”’ 1’ , I I I 0 10 2a 30 40 LABORATORY COMPACTION TEST SOIL CLASSIFICATION BORI116 TREWCN NO. NO. #PM SANDY CLAY. Dark gray-brown. B-l 5’ SANDY SILT with clay. Mottled, tan-gray. B-4 2’ SILTSTONE with clay. Tan-gray. B-8 2' I SWELL TEST DATA I 1 Ii1 31 IllITIAL DRY DENSITY (pcf) 95.8 94.8 96.3 INITIAL WTER ClHTENl (I) 11.5 14.3 16.3 LMIl (Pm 144 144 144 UBC EXPANSION INDEX 1 120 1 127 1 126 1 FIGURE NUMBER I I la JOB NUMBER 88-5405 @Hi -” ATTERBERG LIMiT DETERMINATIONS - - (ASTM D423 AND D424) PLASTICITY INDEX; PI = LL- PL SD 40 30 20 ID 7 4 n ” 10 20 30 40 50 60 70 80 SO 100 LIPUID LIMIT, 11 FIGURE NUMBER Ii I b JOB NUMBER 88-5405 - - - - - -. - -1 t L 4 4 1 I I I I-1-I I I I I I I I I I I I I I I I I I I , I I 8 ! 9 al ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! !! ! I - - - - - - - - - - - - - .- ! - 1 ! I , / LI- I’ ?I o- 0 : d w . (Y 0 (Y . w (ID WmuxI8d-NoI&vaI?OSN03 -. - QUALI.TY ASSURANCE LABORATORY GEOTECHNICAL EXPLORATION, INC. ATTN : WERNER LANDRY 7420 TRADE STREET SAN DIEGG, CA 92121 .- DATE OF REPORT DATE RECEIVED - DATE OF SAMPLE DATE COMPLETED ANALYZED BY SAMPLE TYPE - PROJECT NAME PROJECT NUMBER ANALYSES RESULTS - - - NOVEMBER 16, 1988 NOVEMBER 7, 1988 NOVEMBER 1, 1988 NOVEMBER 15, 1988 MS DW RM LF 2 SOIL CARLSBAD RESEARCH CENTER 88-5405 ANALYSIS: TPH METHOD: DHS * LOG NUMBER SAMPLE ID LOCATION UNITS: MG/KG -------------__-____-------------------------------------------- 11585-88 LOT 6 B-7 @ 15' <0.5 11586-88 LOT 11 B-4 @ 15' <0.5 TPH - TOTAL PETROLEUM HYDROCARBONS l KKCOMKENDED PROCEDURE FROM LEAKING UNDERGROUND FUEL TANK FIELD NANUAL, NAY 1988 LABORATORY DIRECTOR I UlilinQ Address P.O. Boll 22567 San Diio. CA 92122 - \ San Diego 6.555 Nancy Ridge Dr.. Suite 3W San Diego. CA 92121 (619) 566-1060 Fax: (619) 458-9093 ArlLOlU (802) 4684891 orange County * (714) 261-7242 FIGURE NO. Ille - - - - NOVEMBER 16, 1988 GEOTECHNICAL EXPLORATION, INC. ICAP SCAN -METALS SAMPLE TYPE - SOIL LOG NUMBER: 11585-88 11586-88 SAMPLE ID: LOT 6 LOT 11 LOCATION: B-7 @ 15' B-4 @ 15' ANALYSIS UNITS: MG/KG MG/KG ----------------------------------------------------------------- SILVER <0.138 <0.183 ALDMINDM 21,200 20,700 ARSENIC 24.0 14.6 BORON 11.3 9.25 BARIUM 301 170 BERYLLIUM 0.769 0.733 CALCIUM 3,590 2,540 CADMIUM <0.277 <0.367 COBALT 13.8 6.98 CHROMIUM .' 13.2 11.3 COPPER 7.84 <0.275 IRON 26,100 21,300 POTASSIUM 3,360 1,970 MAGNESIUM 8,400 4,610 MANGANESE 306 211 MOLYBDENUM SODIUM NICKEL LEAD ANTIMONY SELENIUM SILICON TIN TITANIUM THALLIUM VANADIUM ZINC ANALYZED BY METHOD 6010 2ii2%%* LABORATORY DIRECTOR <0.173 2,160 5.09 <0.865 5.19 <1.73 <1.04 to.519 640 20.5 52.5 65.4 x0.229 617 5.10 <1.15 <2.29 c2.29 <1.38 2.98 257 5.24 45.8 24.0 QUALITY ASSURANCE LABORATORY - APPENDIX A - APPENDIX A UNIFIED SOIL CLASSIFICATION CHART SOIL DESCRIPTION COARSE-GRAINED More than half of material Is trrgor than l No. 200 aleve GRAVELS, CLEAN GRAVELS More than half of coarse fraction is larger than GW No. 4 sieve size, but smaller than 3” GP GRAVELS WITH FINES (appreciable amount) GM GC SANDS, CLEAN SANDS SW More than half of coarse fraction is smaller than a No. 4 sieve. SP SANDS WITH FINES (appreciable amount) SM SC FINE-GRAINED Yen than half of ~t8rirl fa amdkr tfun l No. 200 slave SILTS AND CLAYS ML Liquid Limit Less Than 50 CL OL MH Liquid Limit Greater Than SO HIGHLY ORGANIC SOILS CH OH PT Well-graded gravels, gravel and sand mix- tures, little or no fines. Poorly graded gravels. gravel and sand mix- tures, little or no fines. Silty gravels, poorly graded gravel-sand-silt mixtures. Clay gravels, poorly graded gravel-sand-silt mixtures. Well-graded sand, gravelly sands, little or no no fines. Poorly graded sands, gravelly sands, little or no fines. Silty sands, poorly graded sand and silty mixtures. Clayey sands, poorly graded sand and clay mixtures. Inorganic silts and very fine sands. rock flour. sandy silt and clayey-silt sand mixtures with a slight plasticity. Inorganic clays of low to medium plasticity. gravelly clays, sandy clays, silty clays. clean clays. Organic silts and organic silty clays of low plasticity. Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts. Inorganic clays of high plasticity, fat clays. Organic clays of medium to high plasticity. Peat and other highly organic soils. -. APPENDIX B -. - - - - - - - APPENDIX B GENERAL EARTHWORK SPECIFICATIONS General The objective of these specifications is to properly establish procedures for the clearing and preparation of the existing natural ground or properly compacted fill to receive new fill; for the selection of the fill material; and for the fill compaction and testing methods to be used. Scop_e of Work -- The earthwork includes all the activities and resources provided by the contractor to construct in a good workmanlike manner all the grades of the filled areas shown In the plans. The major items of work covered in this section include all clearing and grubbing, removing and disposing of materials, preparing areas to be filled, compacting of fill, compacting of backfills, subdrain installations, and all other work. necessary to complete the grading of the filled areas. Site Visit and Site Investiaation 1. The contractor shall visit the site and carefully study it, and make all inspections necessary in order to determine the full extent of the work required to complete all grading iri conformance with the drawings and specifications. The contractor shall satisfy himself as to the nature, location, and extent of the work conditions, the conformation and condition of t’7e existing yround surface; and the type of equipment, labor, and facilities nee&<f prior to and during prosecution of the work. The contractor shall satisfy himself as to the character, quality, and quantity of surface and subsurface materials or obstacles to be encountered. Any inaccuracies or discrepancies between the actual field conditions and the drawings, or between the drawings and specifications, must be brought to the engineer’s attention in order to clarify the exact nature of the work to be performed. 2. A soils investigation report has been prepared for this project by CEI. It is available for review and should be used as a reference to the surface and subsurface soil and bedrock conditions on this project. Any recommendations made in the report of the soil investigation or subsequent reports shall become an addendum to these specifications. B2 - r - - - Authority of the Soils Enqineer and Enqlneerlnq Ceoloqist The soils engineer shall be the owner’s reprerentatlve to observe and test the construction of fills. Excavation and the placing of fill shall be under the observation of the soils engineer and his/her representative, and he/she shall give a written opinion regarding conformance with the specifications upon completion of grading. The soils engineer shall have the authority to cause the removal and replacement of porous topsoils, uncompacted or improperly compacted fills, disturbed bedrock materials, and soft alluvium, and shall have the authority to approve or reject materials proposed for use in the compacted fllj areas. The soils engineer shall have, in conjunction with the engineering geologist, the authority to approve the preparation of natural ground and’ toe-of-fill benches to receive fill material. The engineering geologist shall have the authority to evaluate the stability of the existing or proposed slopes, and to evaluate the necessity of r$.nedial measures. If any unstable condition is being created by cutting or filling, the engineering geologist and/or soils engineer shall advise the contractor and owner immediately, and prohibit grading in the affected area until such time as corrective measures are taken. The owner shall decide all questions regarding: (1) the interpretation of the drawings and specifications, (2) the acceptable fulfillment of the contract on the part of the contractor, and (3) the matter of compensation. Clearina and Grubbing 1. Clearing and grubbing shall consist of the removal from all areas to be graded of all surface trash, abandoned improvements, paving. culverts, pipe. and vegetation (including -- but not limited to -- heavy weed growth, trees, stumps, logs and roots larger than I-inch in diameter). 2. All organic and inorganic materials resulting from the clearing and grubbing operations shall be collected, piled, and disposed of by the contractor to give the cleared areas a neat and finished appearance. Burning of combustible materials on-site shall not !>e permitted unless allowed by local regulations, and at such times and in such a manner to prevent the flre from spreading to areas adjoining the property or cleared area. 3. It is understood that minor amounts of organic materials may remain in the fill soils due to the near impossibility of complete removal. The amount remaining, however, must be considered negligible, and in no case can be allowed to occur in concentrations or total quantities sufficient to contribute to settlement upon deco.aposition. -, 83 - - - - - - - - / - I I ‘I Preparation of Areas to be Filled 1. 2. 3. 4. After clearing and grubbing, ail uncompacted or improperly compacted fills, soft or loose soils, or unsuitable materials, shall be removed to expose competent natural ground, undisturbed bedrock, or properly compacted fill as indicated in the soils investigation report or by our field representative. Where the unsuitable materials are exposed in final graded areas, they shalt be removed and replaced as compacted fill. The ground surface exposed after removal of unsuitable soils shall be scarified to a depth of at least 6 inches, brought to the specified moisture content, and then the scarified ground compacted to at least the specified density. Where undisturbed bedrock is exposed at the surface, scarification and recompaction shall not be required. Ail areas to receive compacted fill, including all removal areas and toe-of-fill benches, shall be observed and approved by the soils engineer and/or engineering geologist prior to placing compacted fill. Where fills are made on hillsides or exposed slope areas with gradients greater than 20 percent, horizontal benches shall be cut into firm, undisturbed, natural ground in order to provide both lateral and vertical stability. This is to provide a horizontal base so that each layer Is placed and compacted on a horizontal plane. The initial bench at the toe of the fill shall be at least 10 feet in width on firm, undisturbed, natural ground at the elevation of the toe stake placed at the bottom of the design slope. The engineer shall determine the width and frequency of all succeeding benches, which will vary with the soil conditions and the steepness of the slope. Ground slopes flatter than 20 percent (5.6: 1.0) shall be benched when considered necessary by the soils engineer. Fill and Backfill Material Unless otherwise specified, the on-site material obtained from the project excavations may be used as fill or backfill, provided that all organic material, rubbish, debris, and other objectionable material contained therein is first removed. In the event that expansive .~_ _ materials are encountered during foundation excavations within 3 feet of finished grade and they have not been properly processed, they shall be entirely removed or thoroughly mixed with good, granular material before incorporating them in fills. No footing shall be allowed to bear on soils which, in the opinion of the soils engineer, are detrimentally expansive -- unless designed for this clayey condition. --, 84 i - - - However, rocks, boulders, broken Portland cement concrete, and bituminous-type pavement obtained from the project excavations may be permitted in the backfill or fill with the following limitations: 1. 2 3. 4. 5. 6. 7. 0. 9. The maximum dimension of any piece used in the top 10 feet shall be no larger than 6 Inches. Clods or hard lumps of earth of 6 inches in greatest dimenslon shall be broken up before compacting the material in fill. if the fill material originating from the project excavation contains large rocks, boulders, or hard lumps that cannot Se broken readily, pieces ranging from 6 Inches In diameter to 2 feet In maximum dimenslon may be used in fills below final subgrade If all pieces are placed in such a manner (such as windrows) as to eliminate nesting or voids between them. No rocks over 4 feet will be allowed in the fill. Pieces larger than 6 Inches shall not be placed within 12 inches of any structure. Pieces larger than 3 inches shall not be placed within 12 inches of the subgrade for paving. Rockfllis containing less than 40 percent of soil passing 3/4-inch sieve may be permitted in designated areas. Specific rec:,:nmendations shall be made by the soils engineer and be subject to approval by the city engineer. Continuous cbservation by the soils engineer is required during rock placement. Special and/or additional recommendations may be provided in writing by the soils engineer to ,modify, clarify, or amplify these specifications. During grading operations, soil types. other than those analyred in the soil investigatlon report may be encountered by the contractor. The solls engineer shall be consulted to evaluate the suitability of these soils as fill materials. Placing and Compactinq Fill Material -- _ _. ----. --- 1. After preparing the areas to be filled, the approved fill material Sll;lll !>e placed in approximately horizontal layers, wlth lift ttrickness compatible to the material being placed and the type of equipment being used. Unless otherwise approved by the soils engineer. each layer spread for compaction shall not exceed 8 inches of loose thickness. Adequate drainage of the fill shall Se provided at all times during the construction period. 35 2. - 3. - 4. 5. - 6. - 7. - I I I When the moisture content of the fill material is below that specified by the engineer, water shall be added to its until the moisture content is as specified. When the moisture content of the fill material is above that specified by the engineer, resulting in inadequate compaction or unstable fill, the fill material shall be aerated by blading and scarifying or other satisfactory methods until the moisture content Is as specified. After each layer has been placed, ‘mixed, and spread evenly, it shall be thoroughly compacted to not less than the density set forth in the specifications. Compaction shall be accomplished with sheepsfoot rollers, multiple-wheel pneumatic-tired rollers, or other approved types of acceptable compaction equipment. Equipment shall be of such design that it will be able to compact the fill to the specified relative compaction. Compaction shall cover the entire fill area, and the equipment shall make sufficient trips to ensure that the desired density has bee7 obtained throughout the entire fill. At locations wheie it would be impractical d:Je to inaccessibility of rolling compacting ‘equipment, fill layers shall be compacted to the specified requirements by hand-directed compaction equipment. When soil types or combination of soil types are encountered which tend to develop densely packed surfaces as a result of spreading or compacting operations, the surface of +sL:.~ layer of fill shall be sufficiently roughened after compaction to ensure bond to the succeeding layer. Unless otherwise specified, fill slopes shall not be steeper than 2.0 horizontal to 1 .O vertical. in general, fill slopes shall be finished in conformance with the lines and grades shown on the plans. The surfaz of fill slopes shall be overfilled to a distance from finished slopes such that it will allow compaction equipment to operate freely within the zone of the finished slope, and then cut back to the finished grade to expose the compacted core. Alternate compaction procedures Include the backroiling of slopes witli 0eepsfoot rollers, in increments of 3 to 5 feet in elevation gain. Alternate methods may be used by the contractor, but they shall be evaluated for approval by the solls engineer. Unless otherwise specified, ail allowed expansive fill material shall be compacted to a moisture content of approximately 2 to 0 percent above the optimum moistclrti content. Nonexpansi ** fill shall be compacted at Ilear-optimum moisture content. All fill shall be compacted, unless otherwise specified, to a relative compaction not less than 95 percent for fill in the upper 12 inches -.~ , 86 - - - - - - of subgrades under areas to be paved with asphalt concrete or Portland concrete, and not less than 90 percent for other fill. The relative colnpaction is the ratio of the dry unit weight of the compacted fill to the laboratory maximum dry unit weight of a sample of the same soil, obtained in accordance with A.S.T.M. O- 1557 test method. a. The observation and periodic testing by the soiis engineer are intended to provide the contractor with an ongoing measure of the quality of the fill compaction operation. it is the responsibility of the grading contractor to utiilze this information to estabilsh the degrees of compactive effort required on the project. ?VlOW importantly, it is the responsibility of the gradlng contractor to ensure that proper compactive effort Is applied at all times during the grading operation, including during the absence of soils engineering representatives. Trench Backfill -.- 1. Trench excavations which extend under graded lots, paved areas, areas under the influence of structural loading, in slopes or close to slope areas, shall be backfilled under the observations and testing of the soils engineer. Ail trenches not falling within the aforementioned locations shall be backfilled in accordance with the City or County regulating agency specifications. 2. IJqiess otherwise specified, the minimum degree of compaction shall be 93 percent of the laboratory maximum dry density. 3. Any soft, spongy, unstable, or other similar material encountered in the trench excavation upon which the bedding material or .pipe is to be placed, shall be removed to a depth recommended by the soils engineer and replaced with bedding materials suitably densified. Bedding material shall first be placed so that the pipe is supported for the full length of the barrel with full bearing on the bottom segment. After the needed testing of the pipe is accomplished, the bedding shall be co?npia’ted to at least 1 foot on top of the pipe. The bedding shall be properly densified before backfill is placed. Bedding shall consist of granular material with a sand equivalent not less than 30, or other material dpproved by the engineer. 4. No rocks greater than 6 inches in diameter will be allowed in the backfill placed between I foot above tha pii>* and 1 foot below finished subgrade. Rocks greater than 2.5 inches in any dimension will not be allowed in the backfill placed within 1 foot of pavement subgrade. 87 5. - - - - - - - - - - - 6. 7. 0. Material for mechanicaiiy compacted backfill shall be placed in lifts of horizontal layers and properly molstened prior to compaction. in addition, the layers shall have a thickness compatible wfth the material being placed and the type of equipment being used. Each layer shall be evenly spread, molstened or dried, and then tamped or roiled until the specified relative compaction has been attained. Backflli shall be mechanically compacted by means of tamplng rollers, sheepsfoot rollers, pneumatic tire rollers, vibratory rollers, or other mechanical tampers. impact-type pavement breakers (stompers) will not be permitted over clay, asbestos cement, plastic, cast Iron, or nonreinforced concrete pipe. Permlssfon to use specific compaction equipment shall not be construed as guaranteeing or implying that the use of such equipment will not result in damage to adjacent ground, existing improvements, or Improvements installed under the contract. The contractor shall make his/her own determlnatlon in this regard. Jetting shall not be permitted as a compaction method unless the soils engineer allows it In writing. Clean granular material shall not be used as backfill or bedding in trenches located in slope areas or within a distance of 10 feet of the top of slopes unless provisions are made for a drainage system to mitigate the potential buildup of seepage forces into the slope mass. I Observations and Testlnq 1. The soils engineers or elr representatives shall sufficiently observe and test the g ng operations so that they can state their opinion as to whe r or not the fill was constructed in accordance with the spec 2. The soils engineers or ir representatives shall take sufficient density tests during placement of compacted fill. The contractor should the soils engineer and/or his/her representatlve by st pits for removal determinations and/or for testing In additlon, the contractor should cooperate wit s engineer by removing or shutting down equipment from the ea being tested. 3. Fill shall be tested for piiance with the recommended relative compaction and moisture Field density testing should be performed by using proved methods by A.S.T.M., such as A.S.T.M. 01556, D2922, d/or D2937. Tests to evaluate density of compacted fill should rovided on the basis of not fess than one test for each 2-foot icai lift of the fill, but not less than one test for each 1.00 bit yards of fill placed. Actual test -. 08 - - - - - - intervals may vary as field conditions dictate. In fill slopes, approximately half of the tests shall be made at the fill slope, except that not more than 0:);~ test needs to be made for each 53 horizontal feet of slope In each Z-foot vertical lift. Actual test intervals may vary as field conditions dictate. 4. Fill found not to be In conformance with the gradlng recommendations should be removed or otherwise handled as recommended by the soils engineer. Site Protection It shall be the grading contractor’s obligation to take all measures deemed necessary durlng grading to maintain adequate safety measures and working conditions, and to provide erosion-control devices for the protection of excavated areas, slope areas, finished work on the site and adjoining properties, from storm damage and flood harar,l originating on the project. It shall be the contractor’s responsibility to maintain slopes in their as-graded form until all slopes are in satisfactory compliance with the jcJ3 specifications, all berms and benches have been properly constructed, and all associated drainage devices have been installed and meet the requirements of the specifications. All observations, testing services, and approvals given by the soils engineer and/or geologist shall not relieve the contractor of his/her responsibilities of performing the work in accordance with these specifications. After grading is completed and the soils engineer has finished his/her observations and/or testing of the work, no further excavation or filling shall be done except under his/her observations. Adverse Weather Conditions 1. Precautions shall be taken by the contractor during the performance of site clearing, excavations, and grading to protect the worksite from flooding, ponding, or Inundation by poor or improper surface drainage. Temporary prov.isioos shall be made during the rainy season to adequately direct surface drainage away from and off the worksite. Where low areas cannot be avoided, pumps should be kept on hand to continually remove water during periods of rainfall. 2. During periods of rainfall, plastic sheeting shall be kept reasonably accessible to prevent uoprotccted slopes from !XCU oir19 saturated. Where necessary during periods of rainfall, the contractor shall install checkdams, desiltlng basins, rip-rap, sandbags, or other devices or methods necessary to control erosion and provide safe conditions. B9 - - 3. During periods of rainfall, the soils engineer should be kept Informed by the contractor as to the nature of remedial or preventative work being performed (e.g. pumping, placement of sandbags or plastic sheeting, other labor, dozing, etc.). - 4. Following periods of rainfall, the contractor shall contact the soils engineer and arrange a walk-over of the site In order to visually assess rain-related damager The soils engineer may also recommend excavations and testing in order to aid in his/her assessments. At the request of the soils engineer, the contractor shall make excavations in order to evaluate the extent of rain- related damage. - - - 5. Rain-related damage shall be considered to Include, but may not be limited to, erosion, silting, saturation, swelling, structural distress, and other adverse conditions Identified by the soils : engineer. Soil adversely affected shall he classified as Unsuitable Materials, and shall be subject to overexcavation and replacement with coq>acted fill or other remedial grading, as recommended by the soils engineer. b. - 7. - - Relatively level areas, w!lere saturated soils and/or erosion gullies exist to depths of greater than 1.0 foot, shall be overexcavated to unaffected, competent material. ‘Where. less than 1.0 foot in depth. unsuitable materials may be processed in place to achieve near-optimum moisture conditions, then thoroughly recompacted in accordance with the applicable specifications. If tile :+?sired results are not achieved, the affected materials shall be over- excavated. then replaced in accordance with the applicable specifications. In slope areas. where saturated soils and/or erosion gullies exist to depths of greater than 1.0 foot, they shall be overexcavated and replaced as compacted fill in accordance with the applicable specifications. Where affected materials exist to depths of 1.9 foot or less below proposed finished grade, remedial grading by moisture-conditioning In place, followed by thorough recompactlon in accordance with the applicable grading guidelines herein presented may he attempted. If materials shall he overexcavated and re&ced .as compacted fill. it shall be done in accordance with the slope-repair recommendations herein. As field conditions dictate, other slope-repair procedures may be recommended by the soils engineer. -., 8‘ 7, - - - ,- - APPENDIX C -. I APPENDIX C GENERAL DISCUSSION OF EXPANSIVE-SOIL BEHAVIOR - - - - - - - - - - - - Expansive-Soil Uplift of Concrete Slabs and Flatwork In general, the measured “doming” -- relatively higher slab areas near the center of a floor slab over expansive soils -- is due to the Inability of moisture accumulating In subslab soils to evaporate, or dry out, as do soils in planters or uncovered yard areas around the structure. The extent to which new floor slabs will “dome” depends on the swell potential of the soil, the initial moisture content of the soil when the slab Is constructed, and the potential for additional wetting of the expansive soil due to surface or subsurface water infiltration. Nonuniform “doming, I* which generally results in more damage than a uniform rise and fall across a slab, is due to variable slab design and reinforcement, variable loads on the slab, nonuniform initial soil characteristics and conditions, and/or differential wetting of the soil by iocalized water sources : (e.g., leaking utility line, ponding of water against a footing, overwatering of planters next to footing, etc. 1. The “Active” Soil Zone In general, the “wettingdrying” zone in Southern California ranges from 2 to 3 feet below a ground surface not covered by some form of moisture barrier (e.g., concrete slab, polyethylene sheeting). This “wettingdrying” zone is the depth to which seasonal rainfall will wet unprotected soil, and the depth to which appreciable drying of unprotected soil (due to evaporation) will occur during summer months. Even if no surface water is allowed to soak into clayey soil which Is uncovered and subject to soil-moisture evaporation, the soil below a certain depth will remain at a relatively constant moisture level. This is due to two mechanisms; temperature decreases and humidity increases result in evaporation being less effective with depth, and soil moisture at depth is constantly drawn up into fine-grained clayey soils by capillary act ion. The bottom of the “wettingdrying” zone is the depth at which evaporative and capillary forces are In a state of equllibrlum. The clayey soil at any given depth below this zone remains at a relatively constant moisture level, and therefore does not under9 volume changes. The soil above the equillbrlum depth -- the “active” soil zone - alternately expands and shrinks (within certain vertical limits) as soil moisture increases and decreases, respectively. Design Criteria for Contemporary Slabs on Expansive Soil When a large, concrete slab is constructed on expansive soil, the under- lying soil in both the “active” zone and the lower “equilibrium” zone is prevented from losing moisture due to evaporation. As a result, soil moistures in the former “equilibrium” zone will rise to a higher soil . . P 0-2 - - - - - - moisture content and, the moisture content In the upper “active zone will increase. In response to the long-term moisture increase, the lightly loaded soils beneath the interior slab areas expand and lift the slab. The perimeter footings and slab areas do not lift as high as interior slab areas because the heavily loaded footings better resist the soil expansion, and because unprotected ground areas adjacent to the slab perimeter allow soil moisture to evaporate from beneath footings and the outermost portions of the slabs. In general, contemporary site development and foundation plans for residential structures on expansive soil are not Intended to eliminate long-term soil-moisture increases beneath a new slab; such a foundation system would not be economlcally feasible for a typical resldentlal structure, and is not considered warranted for such a structure. Instead, current desig, features include: deepened perimeter footings to reduce Infiltration of surface water beneath slabs; sloping of ground surfaces away from all footlngs, to prevent ponding of water next to footings; and placement of reinforcing steel bars or post-tensioned cables in the slabs, to reduce the potential for significant nonuniform slab “doming.” The reinforcing steel is also intended to limit vertical or horizontal separations across any cracks In the concrete slab; it is usually not intended to prevent such cracks from developing. New Concrete Slabs It is important for owners of new homes on expansive soil to realize that capillary rise of moisture beneath new concrete slabs will probably result in some minor slab movement and resultant minor cracking of wall, ceiling and floor coverings. Such minor cracking is ,expected and should be regarded as normal for a residential structure on expansive soil. Maintaining good drainage away from a house perimeter will help to reduce the size and extent of crackJdue to soil movement, but minor cracking will still occur due to long-term moisture Increases beneath the newer concrete slabs. - - Older Concrete Slabs It has been our experience that expansive soils beneath concrete slabs that are more than 8 to 10 years old are typically very moist to wet. Soil-moistures beneath older slabs (due to capillary rise) have usually reached -- or are approaching -- a new “equilibrium” level; in other words, years of capillary rise have Increased the moisture content to a level which probably will not change appreciably over time, so long as significant changes in the general gound water table at depth do not occur. Much of the observed ‘Morning” of an older floor slab probably occurred over past years, while the soil moistures were still increasing up to a hitier “equlllbrlumn level. - . . . .- I I , r - B-3 - - In general, significant movement of an older structure on expansive soil is due primarily to preventable sources of water entering the soil, due to inadequate yard drainags, overwatering of planters adjacent to footings, or leaks in utility lines. Since the soils beneath older concrete slabs are generally much wetter than the ,soils beneath new slabs, the potential for significant soil uplift due only to gnerai capillary rise is low beneath older slabs. Therefore, good long-term performance of an older structure on expansive soil Is dependent on Institution and maintenance of very positive site drainage by the homeowner. If positive drainage is maintained on a longterm basis, then soil moisture levels beneath perimeter footings will stabilize over time. As the soil moisture becomes stabilized, the size and frequency of cracking should become less over time. If the homeowner desires to reduce future damage to a level below what is considered normal and acceptable for a residential structure, this can be accomplished by installing additional moisture-control and/or foundation structures. Such structures might include: 1. 2. 3. 4. 5. 6. 7. 0. locating and repairing any significant cracks in concrete floor slabs; placing a continuous concrete “apron” around the perimeter of a structure; placing a subsurface french- drain or moisture’ cut-off wall around a structure; intrusion-grouting the soil beneath perimeter footings to reduce moisture infiltration; deepening the perimeter footing; replacing interior floor slabs with a new, more heavily reinforced slab; replacing interior floor slabs with a very thick mat foundation reinforced with grids of conventional steel bars or post-tensioned cables; andfor placing the entire structure on a raised pier-and-grade-beam foundation.