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HomeMy WebLinkAboutRP 16-12; ARMY AND NAVY STUDENT ENRICHMENT CENTER; UPDATE GEOTECHNICAL REPORT; 2019-01-03January 3, 2019 Army and Navy Academy 2605 Carlsbad Boulevard Carlsbad, California 92008 Attention: General Art BarteH w CHRJSTIAN WHEELER. ENG IN EER.ING RECORD COPY lnithtJ Data Subject: Update Geotechnical Report Army & Navy Academy Student Enrichment Center 2600 Carlsbad Boulevard, Carlsbad, California CWE 2180688.01 FEB 13 2019 References: 1) Toal Engineering, Inc., Grading and Erosion plans for Army & Navy Student Enrichment Center, November 12, 2018 2) Christian Wheeler Engineering, Report 2120311.17, dated October 4, 2013 3) Christian Wheeler Engineering, Report 2120311.02R, dated August 2, 2012 Ladies and Gentlemen: In accordance with your request, and our proposal dated December 5, 2018, Christian Wheeler Engineering has prepared this update of the referenced preliminary geotechnical investigation report. SITE INFORMATION AND PROJECT DESCRIPTION The subject site consists of an irregular parcel of land located south of the Army Navy Academy Sports Complex, at 2600 Carlsbad Boulevard, Carlsbad, California. The site is bounded on the north by a multipurpose playing field, on the east by a parking lot, and on the south by a State of California structure and associated paved parking. Topographically, the site is near flat-lying, with an elevation of approximately 47 feet; however, 4-foot-high ascending slope exists along the southern property line. A retaining wall about 3 feet high exists at the top of the slope. A retaining wall up to about 7 feet high exists at the northern perimeter of the pad. The wall retains the subject site. The site was graded 3980 H o me Ave nu e ♦ San Diego , CA 92105 ♦ 619-550 -1 7 00 ♦ FAX 619-550 -1701 -- . -+-' C CWE 2180688.01 January 3, 2019 Page No. 2 between 2012 and 2013 in conjunction with the construction of the athletic field. Grading consisted of cuts and fills about 2 feet deep. It appears that the site remains essentially unchanged. We understand that a Student Enrichment Center will be constructed at the site. We assume that the two-story structure will be of wood-frame construction, will be supported by shallow foundations and incorporate a conventional concrete slab-on-grade floor system. Exterior retaining walls up to about 4 feet high and associated hardscape are anticipated. Grading to accommodate the proposed improvements is expected to consist of cuts up to approximately 4 feet from existing grades. SCOPE OF SERVICES The scope of our services consisted of a site reconnaissance, a review of our referenced geotechnical reports and a limited review of the referenced grading plan. The scope of services included providing any additional geotechnical recommendations that, in our opinion, are considered necessary, and providing updated seismic design parameters for the proposed project based on the 2016 edition of the California Building Code (CBC). SUBSURFACE CONDITIONS A review of the referenced reports indicates that the subject site is primarily underlain by old paralic deposits and minor artificial fill associated with existing retaining wall construction. Based on information from a boring located near the site, it is anticipated that the old paralic deposits consist of about 4 feet of loose to medium dense silty sand (SM) underlain by medium dense to dense poorly graded silty sand with silt (SM-SP). The artificial fill is likely derived from these materials. CONCLUSIONS In general, it is our professional opinion and judgment that the subject property is suitable for the construction of the subject project and associated improvements provided the recommendations presented herein are implemented. The main geotechnical condition encountered affecting the proposed project is potentially compressible old paralic deposits and temporary cut slopes associated with the proposed construction. CWE 2180688.01 January 3, 2019 Page No. 3 Potentially compressible old paralic deposits are anticipated to underlie the project area. Based on the information available, these materials extend to a maximum depth of about 4 feet below existing grade However, deeper compressible soils may exist. These deposits are considered unsuitable, in their present condition, for the support of settlement sensitive improvements. It is recommended that these materials be removed and replaced as compacted fill. Temporary cut slopes associated with the construction of a retaining wall will be necessary in relatively close proximity to the southern property line, where an offsite retaining wall exists. It is conceivable that proposed cuts will expose competent old paralic deposits at proposed foundation level; however, additional cuts associated with recommended site preparation may be needed if this is not the case. It is further anticipated that the old paralic deposits at relatively shallow depths may consist of cohesionless sands that will require flatter than usual temporary cuts slope inclination. Additionally, the configuration of the existing retaining footing is unknown and could further hamper temporary cut slope construction. It is recommended that his area be investigated at the on-set of grading operations to verify if special grading recommendations are necessary. RECOMMENDATIONS GRADING AND EARTHWORK GENERAL: All grading should conform to the guidelines presented in the current edition of the California Building Code, the minimum requirements of the City of Carlsbad, and the recommended Grading Specifications and Special Provisions attached hereto, except where specifically superseded in the text of this report. PREGRADE MEETING: It is recommended that a pregrade meeting including the grading contractor, the client, and a representative from Christian Wheeler Engineering be performed, to discuss the recommendations of this report and address any issues that may affect grading operations. CLEARING AND GRUBBING: Site preparation should begin with the removal of any existing vegetation and other deleterious materials in areas to receive proposed improvements or new fill soils. CWE 2180688.01 January 3, 2019 Page No. 4 SITE PREPARATION: It is recommended that existing potentially compressible soils underlying the proposed settlement sensitive improvements and new fills should be removed in their entirety. Based on our findings, the maximum anticipated removal depth is about 4 feet from existing grade. Deeper removals may be necessary in areas of the site not investigated, due to unforeseen condition. Lateral removals limits should extend at least 5 feet from the perimeter of the improvements and new fills or equal to removal depth, whichever is more. No removals are recommended within 2 feet from existing perimeter retaining walls and beyond property lines. All excavated areas should be approved by the geotechnical engineer or his representative prior to replacing any of the excavated soils. The excavated materials can be replaced as properly compacted fill in accordance with the recommendations presented in the "Compaction and Method of Filling" section of this report. PROCESSING OF FILL AREAS: Prior to placing any new fill soils or constructing any new improvements in areas that have been cleaned out to receive fill, the exposed soils should be scarified to a depth of about 6 inches, moisture conditioned, and compacted to at least 90 percent relative compaction. COMPACTION AND METHOD OF FILLING: In general, all structural fill placed at the site should be compacted to a relative compaction of at least 90 percent of its maximum laboratory dry density as determined by ASTM Laboratory Test D1557. Fills should be placed at or slightly above optimum moisture content, in lifts six to eight inches thick, with each lift compacted by mechanical means. Fills should consist of approved earth material, free of trash or debris, roots, vegetation, or other materials determined to be unsuitable by the Geotechnical Consultant. Fill material should be free of rocks or lumps of soil in excess of 3 inches in maximum dimension. Utility trench backfill within 5 feet of the proposed structure and beneath all concrete flatwork or pavements should be compacted to a minimum of 90 percent of its maximum dry density. SURFACE DRAINAGE: The drainage around the proposed improvements should be designed to collect and direct surface water away from proposed improvements toward appropriate drainage facilities. Rain gutters with downspouts that discharge runoff away from the structure into controlled drainage devices are recommended. CWE 2180688.01 January 3, 2019 Page No. 5 The ground around the proposed improvements should be graded so that surface water flows rapidly away from the improvements without ponding. In general, we recommend that the ground adjacent to structure slope away at a gradient of at least 5 percent for a minimum distance of 10 feet. If the minimum distance of 10 feet cannot be achieved, an alternative method of drainage runoff away from the building at the termination of the 5 percent slope will need to be used. Swales and impervious surfaces that are located within 10 feet of the building should have a minimum slope of 2 percent. It is essential that new and existing drainage patterns be coordinated to produce proper drainage. Drainage patterns provided at the time of construction should be maintained throughout the life of the proposed improvements. Site irrigation should be limited to the minimum necessary to sustain landscape growth. Over watering should be avoided. Should excessive irrigation, impaired drainage, or unusually high rainfall occur, zones of wet or saturated soil may develop. TEMPORARY CUT SLOPES The contractor is solely responsible for designing and constructing stable, temporary excavations and will need to shore, slope, or bench the sides of trench excavations as required to maintain the stability of the excavation sides. The contractor's "competent person", as defined in the OSHA Construction Standards for Excavations, 29 CFR, Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety process. We anticipate that the existing on-site soils will consist of Type C material. Our firm should be contacted to observe all temporary cut slopes during grading to ascertain that no unforeseen adverse conditions exist. No surcharge loads such as foundation loads, or soil or equipment stockpiles, vehicles, etc. should be allowed within a distance from the top of temporary slopes equal to half the slope height. FOUNDATIONS GENERAL: Based on our findings and engineering judgment, the proposed structure and associated improvements may be supported by conventional shallow continuous and isolated spread footings founded in newly compacted fill. The following recommendations are considered the minimum based on the anticipated soil conditions, and are not intended to be lieu of structural considerations. All foundations should be designed by a qualified engineer. CWE 2180688.01 January 3, 2019 Page No. 6 DIMENSIONS: Spread footings supporting the proposed structure and associated improvements should be embedded at least 12 inches below lowest adjacent finish pad grade. Continuous and isolated footings should have a minimum width of 12 inches and 24 inches, respectively. Retaining wall footings should be at least 24 inches wide. BEARING CAPACITY: Spread footings supporting the proposed structure and associated improvements founded on either newly compacted fill or old paralic deposits may be designed for an allowable soil bearing pressure of 2,000 pounds per square foot. This value may be increased by 600 pounds per square foot for each additional foot of embedment and 400 pounds per square foot for each additional foot of width up to a maximum of 4,000 pounds per square foot. This value may be increased by one-third for combinations of temporary loads such as those due to wind or seismic loads. FOOTING REINFORCING: Reinforcement requirements for foundations should be provided by a structural designer. However, based on the expected soil conditions, we recommend that the minimum reinforcing for continuous footings consist of at least 2 No. 5 bars positioned near the bottom of the footing and 2 No. 5 bars positioned near the top of the footing. LATERAL LOAD RESISTANCE: Lateral loads against foundations may be resisted by friction between the bottom of the footing and the supporting soil, and by the passive pressure against the footing. The coefficient of friction between concrete and soil may be considered to be 0.30. The passive resistance ~ay be considered to be equal to an equivalent fluid weight of 300 pounds per cubic foot. These values are based on the assumption that the footings are poured tight against undisturbed soil. If a combination of the passive pressure and friction is used, the friction value should be reduced by one- third. FOUNDATION EXCAVATION OBSERVATION: All footing excavations should be observed by Christian Wheeler Engineering prior to placing of forms and reinforcing steel to determine whether the foundation recommendations presented herein are followed and that the foundation soils are as anticipated in the preparation of this report. All footing excavations should be excavated neat, level, and square. All loose or unsuitable material should be removed prior to the placement of concrete. SETTLEMENT CHARACTERISTICS: The anticipated total and differential settlement is expected to be less than about 1 inch and 1 inch over 40 feet, respectively, provided the recommendations CWE 2180688.01 January 3, 2019 Page No. 7 presented in this report are followed. It should be recognized that minor cracks normally occur in concrete slabs and foundations due to concrete shrinkage during curing or redistribution of stresses, therefore some cracks should be anticipated. Such cracks are not necessarily an indication of excessive vertical movements. EXPANSIVE CHARACTERISTICS: The prevailing foundation soils are assumed to have a low expansive potential (EI between 21 and 50). The recommendations within this report reflect these conditions. FOUNDATION PLAN REVIEW: The final foundation plan and accompanying details and notes should be submitted to this office for review. The intent of our review will be to verify that the plans used for construction reflect the minimum dimensioning and reinforcing criteria presented in this section and that no additional criteria are required due to changes in the foundation type or layout. It is not our intent to review structural plans, notes, details, or calculations to verify that the design engineer has correctly applied the geotechnical design values. It is the responsibility of the design engineer to properly design/ specify the foundations and other structural elements based on the requirements of the structure and considering the information presented in this report. SEISMIC DESIGN FACTORS The seismic design factors applicable to the subject site are provided below. The seismic design factors were determined in accordance with the 2016 California Building Code. The site coefficients and adjusted maximum considered earthquake spectral response acceleration parameters are presented in the following Table I. TABLE I: SEISMIC DESIGN FACTORS Site Coordinates: Latitude 33 .162° Longitude -117.354° Site Class D Site Coefficient Fa 1.0 Site Coefficient Fv 1.351 Spectral Response Acceleration at Short Periods S, 1.169 g Spectral Response Acceleration at 1 Second Period S1 0.449 g SMs=FaSs 1.169 g SM1=FvS1 0.606 g Sos=2/3'~SMs 0.779 g So1=2/3'~SM1 0.404 g CWE 2180688.01 January 3, 2019 Page No. 8 Probable ground shaking levels at the site could range from slight to moderate, depending on such factors as the magnitude of the seismic event and the distance to the epicenter. It is likely that the site will experience the effects of at least one moderate to large earthquake during the life of the proposed improvements. ON-GRADE CONCRETE SLABS GENERAL: It is our understanding that the floor system of the proposed structure will consist of a concrete slab-on-grade. The following recommendations are considered the minimum slab requirements based on the soil conditions and are not intended in lieu of structural considerations. These recommendations assume that the site preparation recommendations contained in this report are implemented. INTERIOR FLOOR SLABS: The minimum slab thickness should be 4 inches (actual) and the slab should be reinforced with at least No. 3 bars spaced at 18 inches on center each way. Slab reinforcement should be supported on chairs such that the reinforcing bars are positioned at mid- height in the floor slab. The slab reinforcement should extend down into the perimeter footings at least 6 inches. Slabs located adjacent to existing footings or slabs should be doweled as recommended by the project structural designer. UNDER-SLAB VAPOR RETARDERS: Steps should be taken to minimize the transmission of moisture vapor from the subsoil through the interior slabs where it can potentially damage the interior floor coverings. Local industry standards typically include the placement of a vapor retarder, such as plastic, in a layer of coarse sand placed directly beneath the concrete slab. Two inches of sand are typically used above and below the plastic. The vapor retarder should be at least 15-mil Stegowrap® or similar material with sealed seams and should extend at least 12 inches down the sides of the interior and perimeter footings. The sand should have a sand equivalent of at least 30, and contain less than 10% passing the Number 100 sieve and less than 5% passing the Number 200 sieve. The membrane should be placed in accordance with the recommendation and consideration of ACI 302, "Guide for Concrete Floor and Slab Construction" and ASTM E1643, "Standards Practice for Installation of Water Vapor Retarder Used in Contact with Earth or Granular Fill Under Concrete Slabs." It is the flooring contractor's responsibility to place floor coverings in accordance with the flooring manufacturer specifications. CWE 2180688.01 January 3, 2019 Page No. 9 EXTERIOR CONCRETE FLA TWORK: Exterior concrete slabs on grade should have a minimum thickness of 4 inches and be reinforced with at least No. 4 bars placed at 18 inches on center each way (ocew). Driveway slabs should have a minimum thickness of 5 inches and be reinforced with at least No. 4 bars placed at 12 inches ocew. All slabs should be provided with weakened plane joints in accordance with the American Concrete Institute (ACI) guidelines. Special attention should be paid to the method of concrete curing to reduce the potential for excessive shrinkage cracking. It should be recognized that minor cracks occur normally in concrete slabs due to shrinkage. Some shrinkage cracks should be expected and are not necessarily an indication of excessive movement or structural distress. EARTH RETAINING WALLS FOUNDATIONS: Foundations for any proposed retaining walls should be constructed in accordance with the foundation recommendations presented previously in this report. PASSIVE PRESSURE: The passive pressure for the anticipated foundation soils at the underground portion of the structure may be considered to be 300 pounds per square foot per foot of depth. The passive pressure may be increased by one-third for seismic loading. The coefficient of friction for concrete to soil may be assumed to be 0.30 for the resistance to lateral movement. When combining frictional and passive resistance, the friction should be reduced by one-third. ACTIVE PRESSURE: The active soil pressure for the design of "unrestrained" earth retaining structures with level backfill may be assumed to be equivalent to the pressure of a fluid weighing 35 pounds per cubic foot. This pressure does not consider any surcharge. If any are anticipated, this office should be contacted for the necessary increase in soil pressure. These values are based on a drained backfill condition. WATERPROOFING AND WALL DRAINAGE SYSTEMS: The need for waterproofing should be evaluated by others. If required, the project architect should provide (or coordinate) waterproofing details for the retaining walls. The design values presented above are based on a drained backfill condition and do not consider hydrostatic pressures. Unless hydrostatic pressures are incorporated into the design, the retaining wall designer should provide a detail for a wall drainage system. Typical retaining wall drain system details are presented as Plate No. 1 of this report for informational CWE 2180688.01 January 3, 2019 Page No. 10 purposes. Additionally, outlets points for the retaining wall drain system should be coordinated with the project civil engineer. BACKFILL: Retaining wall backfill soils should be compacted to at least 90 percent relative compaction. Expansive or clayey soils should not be used for backfill material. The wall should not be backfilled until the masonry has reached an adequate strength. CLOSURE If you have any questions after reviewing this report, please do not hesitate to contact our office. This opportunity to be of professional service is sincerely appreciated. Respectfully submitted, DBA:tsw encl: Plate 1 Appendix A-Grading Specifications ec: 2180688.01 I]] DETAIL w DETAIL 12" MIN. " 5 ~; •" S'« ~-----•'----~· ~s NOTES AND DETAILS GENERAL NOTES: 1) THE NEED FOR WATERPROOFING SHOULD BE EVALUATED BY OTHERS. 5 7 2) WATERPROOFING TO BE DESIGNED BY OTHERS (CWE CAN PROVIDE A DESIGN IF REQUESTED). 3) EXTEND DRAIN TO SUIT ABLE DISCHARGE POINT PER CIVIL ENGINEER. 4 D N T E RFA DRAIN T IN T M. DETAILS: CD ® G) 4-INCH PERFORATED PVC PIPE ON TOP OF FOOTING, HOLES POSITIONED DO WNW ARD (SOR 35, SCHEDULE 40, OR EQUIVALENT). ¾ INCH OPEN-GRADED CRUSHED AGGREGATE. GEOFARBRIC WRAPPED COMPLETELY AROUND ROCK. G) PROPERLY COMP ACTED BACKFILL SOIL. '5' WALL DRAINAGE PANELS (MIRADRAIN OR EQUIVALENT) '-V PLACED PER MANUFACTURER'S REC'S. © 0 UNDERLAY SUBDRAIN WITH AND CUT FABRIC BACK FROM DRAINAGE PANELS AND WRAP FABRIC AROUND PIPE. COLLECTION DRAIN (TOTAL DRAIN OR EQUIVALENT) LOCATED AT BASE OF WALL DRAINAGE PANEL PER MANUFACTURER'S RECOMMENDATIONS. ARMY & NA VY ACADEMY STUDENT ENRICHMENT CENTER 2600 CARLSBAD BOULEVARD CANTILEVER RETAINING WALL DRAINAGE SYSTEMS DATE: BY: SAN DIEGO, CALIFORNIA JANUARY 2019 JOB NO.: SRD PLATE NO.: 2180688.01 CHRISTIAN WHEELER ENGINEERING Appendix A Grading Specifications CWE 2180688.01 January 3, 2018 Appendix A, Page A-1 RECOMMENDED GRADING SPECIFICATIONS -GENERAL PROVISIONS ARMY & NA VY ACADEMY STUDENT ENRICHMENT CENTER 2600 CARLSBAD BOULEY ARD CARLSBAD, CALIFORNIA GENERAL INTENT The intent of these specifications is to establish procedures for clearing, compacting natural ground, preparing areas to be filled, and placing and compacting fill soils to the lines and grades shown on the accepted plans. The recommendations contained in the preliminary geotechnical investigation report and/ or the attached Special Provisions are a part of the Recommended Grading Specifications and shall supersede the provisions contained hereinafter in the case of conflict. These specifications shall only be used in conjunction with the geotechnical report for which they are a part. No deviation from these specifications will be allowed, except where specified in the geotechnical report or in other written communication signed by the Geotechnical Engineer. OBSERVATION AND TESTING Christian Wheeler Engineering shall be retained as the Geotechnical Engineer to observe and test the earthwork in accordance with these specifications. It will be necessary that the Geotechnical Engineer or his representative provide adequate observation so that he may provide his opinion as to whether or not the work was accomplished as specified. It shall be the responsibility of the contractor to assist the Geotechnical Engineer and to keep him apprised of work schedules, changes and new information and data so that he may provide these opinions. In the event that any unusual conditions not covered by the special provisions or preliminary geotechnical report are encountered during the grading operations, the Geotechnical Engineer shall be contacted for further recommendations. If, in the opinion of the Geotechnical Engineer, substandard conditions are encountered, such as questionable or unsuitable soil, unacceptable moisture content, inadequate compaction, adverse weather, etc., construction should be stopped until the conditions are remedied or corrected or he shall recommend rejection of this work. CWE 2180688.01 January 3, 2018 Appendix A, Page A-2 Tests used to determine the degree of compaction should be performed in accordance with the following American Society for Testing and Materials test methods: Maximum Density & Optimum Moisture Content -ASTM D1557 Density of Soil In-Place -ASTM D1556 or ASTM D2922 All densities shall be expressed in terms of Relative Compaction as determined by the foregoing ASTM testing procedures. PREPARATION OF AREAS TO RECEIVE FILL All vegetation, brush and debris derived from clearing operations shall be removed, and legally disposed of. All areas disturbed by site grading should be left in a neat and finished appearance, free from unsightly debris. After clearing or benching the natural ground, the areas to be filled shall be scarified to a depth of 6 inches, brought to the proper moisture content, compacted and tested for the specified minimum degree of compaction. All loose soils in excess of 6 inches thick should be removed to firm natural ground which is defined as natural soil which possesses an in-situ density of at least 90 percent of its maximum dry density. When the slope of the natural ground receiving fill exceeds 20 percent (5 horizontal units to 1 vertical unit), the original ground shall be stepped or benched. Benches shall be cut to a firm competent formational soil. The lower bench shall be at least 10 feet wide or 1-1/2 times the equipment width, whichever is greater, and shall be sloped back into the hillside at a gradient of not less than two (2) percent. All other benches should be at least 6 feet wide. The horizontal portion of each bench shall be compacted prior to receiving fill as specified herein for compacted natural ground. Ground slopes flatter than 20 percent shall be benched when considered necessary by the Geotechnical Engineer. Any abandoned buried structures encountered during grading operations must be totally removed. All underground utilities to be abandoned beneath any proposed structure should be removed from within 10 feet of the structure and properly capped off. The resulting depressions from the above CWE 2180688.01 January 3, 2018 Appendix A, Page A-3 described procedure should be backfilled with acceptable soil that is compacted to the requirements of the Geotechnical Engineer. This includes, but is not limited to, septic tanks, fuel tanks, sewer lines or leach lines, storm drains and water lines. Any buried structures or utilities not to be abandoned should be brought to the attention of the Geotechnical Engineer so that he may determine if any special recommendation will be necessary. All water wells which will be abandoned should be backfilled and capped in accordance to the requirements set forth by the Geotechnical Engineer. The top of the cap should be at least 4 feet below finish grade or 3 feet below the bottom of footing whichever is greater. The type of cap will depend on the diameter of the well and should be determined by the Geotechnical Engineer and/ or a qualified Structural Engineer. FILL MATERIAL Materials to be placed in the fill shall be approved by the Geotechnical Engineer and shall be free of vegetable matter and other deleterious substances. Granular soil shall contain sufficient fine material to fill the voids. The definition and disposition of oversized rocks and expansive or detrimental soils are covered in the geotechnical report or Special Provisions. Expansive soils, soils of poor gradation, or soils with low strength characteristics may be thoroughly mixed with other soils to provide satisfactory fill material, but only with the explicit consent of the Geotechnical Engineer. Any import material shall be approved by the Geotechnical Engineer before being brought to the site. PLACING AND COMPACTION OF FILL Approved fill material shall be placed in areas prepared to receive fill in layers not to exceed 6 inches in compacted thickness. Each layer shall have a uniform moisture content in the range that will allow the compaction effort to be efficiently applied to achieve the specified degree of compaction. Each layer shall be uniformly compacted to the specified minimum degree of compaction with equipment of adequate size to economically compact the layer. Compaction equipment should either be specifically designed for soil compaction or of proven reliability. The minimum degree of compaction to be achieved is specified in either the Special Provisions or the recommendations contained in the preliminary geotechnical investigation report. CWE 2180688.01 January 3, 2018 Appendix A, Page A-4 When the structural fill material includes rocks, no rocks will be allowed to nest and all voids must be carefully filled with soil such that the minimum degree of compaction recommended in the Special Provisions is achieved. The maximum size and spacing of rock permitted in structural fills and in non- structural fills is discussed in the geotechnical report, when applicable. Field observation and compaction tests to estimate the degree of compaction of the fill will be taken by the Geotechnical Engineer or his representative. The location and frequency of the tests shall be at the Geotechnical Engineer's discretion. When the compaction test indicates that a particular layer is at less than the required degree of compaction, the layer shall be reworked to the satisfaction of the Geotechnical Engineer and until the desired relative compaction has been obtained. Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable equipment. Compaction by sheepsfoot roller shall be at vertical intervals of not greater than four feet. In addition, fill slopes at a ratio of two horizontal to one vertical or flatter, should be trackrolled. Steeper fill slopes shall be over-built and cut-back to finish contours after the slope has been constructed. Slope compaction operations shall result in all fill material six or more inches inward from the finished face of the slope having a relative compaction of at least 90 percent of maximum dry density or the degree of compaction specified in the Special Provisions section of this specification. The compaction operation on the slopes shall be continued until the Geotechnical Engineer is of the opinion that the slopes will be surficially stable. Density tests in the slopes will be made by the Geotechnical Engineer during construction of the slopes to determine if the required compaction is being achieved. Where failing tests occur or other field problems arise, the Contractor will be notified that day of such conditions by written communication from the Geotechnical Engineer or his representative in the form of a daily field report. If the method of achieving the required slope compaction selected by the Contractor fails to produce the necessary results, the Contractor shall rework or rebuild such slopes until the required degree of compaction is obtained, at no cost to the Owner or Geotechnical Engineer. CWE 2180688.01 January 3, 2018 Appendix A, Page A-5 CUT SLOPES The Engineering Geologist shall inspect cut slopes excavated in rock or lithified formational material during the grading operations at intervals determined at his discretion. If any conditions not anticipated in the preliminary report such as perched water, seepage, lenticular or confined strata of a potentially adverse nature, unfavorably inclined bedding, joints or fault planes are encountered during grading, these conditions shall be analyzed by the Engineering Geologist and Geotechnical Engineer to determine if mitigating measures are necessary. Unless otherwise specified in the geotechnical report, no cut slopes shall be excavated higher or steeper than that allowed by the ordinances of the controlling governmental agency. ENGINEERING OBSERVATION Field observation by the Geotechnical Engineer or his representative shall be made during the filling and compaction operations so that he can express his opinion regarding the conformance of the grading with acceptable standards of practice. Neither the presence of the Geotechnical Engineer or his representative or the observation and testing shall release the Grading Contractor from his duty to compact all fill material to the specified degree of compaction. SEASON LIMITS Fill shall not be placed during unfavorable weather conditions. When work is interrupted by heavy rain, filling operations shall not be resumed until the proper moisture content and density of the fill materials can be achieved. Damaged site conditions resulting from weather or acts of God shall be repaired before acceptance of work. RECOMMENDED GRADING SPECIFICATIONS -SPECIAL PROVISIONS RELATIVE COMPACTION: The minimum degree of compaction to be obtained in compacted natural ground, compacted fill, and compacted backfill shall be at least 90 percent. For street and CWE 2180688.01 January 3, 2018 Appendix A, Page A-6 parking lot subgrade, the upper six inches should be compacted to at least 95 percent relative compaction. EXPANSIVE SOILS: Detrimentally expansive soil is defined as clayey soil which has an expansion index of 50 or greater when tested in accordance with the Uniform Building Code Standard 29-2. OVERSIZED MATERIAL: Oversized fill material is generally defined herein as rocks or lumps of soil over 6 inches in diameter. Oversized materials should not be placed in fill unless recommendations of placement of such material should be provided by the Geotechnical Engineer. At least 40 percent of the fill soils shall pass through a No. 4 U .S. Standard Sieve. TRANSITION LOTS: Where transitions between cut and fill occur within the proposed building pad, the cut portion should be undercut a minimum of one foot below the base of the proposed footings and recompacted as structural backfill. In certain cases that would be addressed in the geotechnical report, special footing reinforcement or a combination of special footing reinforcement and undercutting may be required.