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HomeMy WebLinkAboutSDP 00-06A; DAYBREAK COMMUNITY CHURCH; UPDATE OF COMPACTION REPORT FOR PROPOSED 2-STORY BUILDING ADDITION; 2009-04-08\ \VINTE & MIDDLETON ENGINEERING, INC. 2450 Auto Park Way Escondido, California 92029-1229 Job #09-159-F Phonc (760) 743-1214 Fax (760) 739-0343 April 8, 2009 RECEIVED Daybreak Community Church of Coastal North County NOV 1 6 2009 Attention: Mr. Gary Webb 5835 Avenida Encinas, Suite #118 ENGINEERING Carlsbad, California 92008 DEPARTMENT UPDATE OF COMPACTION REPORT FOR PROPOSED 2-STORY BUILDING ADDITION, BUILDING "B", DAYBREAK COMMUNITY CHURCH, LOCATED AT 6515 AMBROSIA LANE, CARLSBAD In accordance with the request of Mr. Jim Thayer of Timeless Architecture, and the requirement set forth in a report previously prepared by this office for review after six months, this report is written to bring the foundation recommendations put forth in that report into current standards, and to discuss remedial grading that will be required prior to construction of the proposed residence. I. REFERENCES CLW The following listed Site Plan and document have been reviewed in order to provide this update C1 report: I.i..1 -J Site Plan prepared by Timeless Architecture. L. "R-Value Test Result, Pavement/Base Thickness and Sub/Basegrade Recommendations For On Site Improvements, Daybreak Community Church", report prepared by this office, dated - August 10, 2001, Job #00-248-F. "As-Graded Compaction Report and Foundation Recommendations For Proposed Daybreak Community Church, Lot #8, Map #13434, Located at 6515 Ambrosia Lane, City of Carlsbad Drawing #392-6A", prepared by this office, dated August 17, 2001, Job #00-248-F. H. SITE INFORMATION This site was previously graded as a "cut" lot during bulk grading operations conducted from September 1996 through June 1998 for the Aviara Phase II project. A final as-graded compaction report was issued by Geotechnics Incorporated, dated June 25, 1998. a z CO) w I C.) z 4 —j Update Compaction Report, Proposed 2-Story Building Addition Page 2 Daybreak Community Church of Coastal North County April 8, 2009 Our involvement in 2001 included grading operations to finalize elevations in order to provide a near flat area for the proposed building and parking areas. Grading observations and compaction testing were conducted periodically by this office during the remedial and fine grading operations, for the period of July 25, 2001 through August 13,2001. An as-graded compaction report with compaction results and foundation recommendations was issued by this office as indicated above. Grading was conducted in substantial conformance with Appendix Chapter 33, latest edition of the California Building Code, and the Grading Ordinance for the City of Carlsbad. All observations and testing, were conducted by a representative from this office as indicated above. In our opinion, all embankments and excavations were constructed in substantial conformance with the provided grading plan, and are acceptable for their intended use. A site inspection was made by a representative from this office on March 25, 2009, and found the site to be visually the same with respect to pad elevation, location of, and height of cut and fill slopes. Therefore, the building pad remains substantially as reported in the subject report. It is our understanding that a new 2-story classroom building supported on shallow stiff concrete footings with slab on grade construction is planned directly south the existing worship center. The existing parking and curbs are to be removed prior to construction. M. APPROPRIATE LABORATORY TESTS Maximum Dry Density Optimum Moisture Tests: The maximum dry density and optimum moisture contents ofthe different soil types used as compacted fill were determined in accordance with ASTM Method D-1557 during the previous grading operations. Expansion Tests: Expansion tests were conducted per 2001 UBC Standard Procedure 18-2 on a representative sample of the "clayey" soils during the previous grading operations of Aviara Phase ii, in order to determine the expansion potential and to provide appropriate foundation recommendations. As no new soils were encountered during our involvement, no additional testing was conducted. Direct Shear Tests: Direct shear tests were conducted on representative samples of the on site soils during the previous grading operations of Aviara Phase II in order to determine the allowable bearing capacity and to provide retaining wall design parameters. As no new soils were encountered during the grading operations, no additional testing was conducted. Corrosion Testing: pH-Resistivity, sulfate, and chloride testing will be conducted on the foundation soils after the completion.of remedial grading operations. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Auto Park Ways Escondido, California 92022-1229 Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 3 Daybreak Community Church of Coastal North County April 8, 2009 1V. RECOMMENDATIONS A. Remedial Grading Remove the existing parking asphalt, curbs and sidewalks. Fine grading will be required in order to provide a level area for the proposed building and associated improvements. Areas outside the pavement were found to be soft and compressible to a depth of one to three feet, and are no longer suitable for the support of structures. Removal and re- compact of the upper soils can be determined after removal of the paved parking area. Based on the limited information of the soils beneath- the currently paved areas, it is recommended that the upper soils to a minimum depth of 3-feet or 12 inches below the bottom of the deepest footing be removed and re-compacted where ever structures are to be placed. Removals should include the structure's footprint, plus a 5 foot perimeter where possible. The bottom ofthe excavations should be "ripped" an additional 6 inches, moisture conditioned to near optimum moisture content, and compacted to a minimum of 90% of the corresponding laboratory maximum dry density. The bacidill of the excavations should also be moisture conditioned and re-compacted as described above. Testing is to be conducted to confirm minimum compaction requirements. Shallower removals and re-compact beneath proposed concrete flatwork outside of the 5-foot building perimeter will be required based-on site conditions found after removal of the existing paved parking area. 5. All abandoned underground utilities should be removed and the backfill of the trenching be properly compacted to a minimum of 90%. 6. Any import soils shall be approved by the project geotechnical engineer prior to delivery to the site. B. Foundations, Monolithic Pour System Conventional shallow foundations with stem walls and slab-on-grade floors, or slab-on-ground with turned-down footings. PLEASE NOTE THAT THESE RECOMMENDATIONS SUPERSEDE THOSE PUT FORTH IN ANY PREVIOUS REPORTS VINJE & MIDDLETON ENGINEERING, INC. '2450 Auto Park Way • Escondido, California 92029-1229 0 Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 4 Daybreak Community Church of Coastal North County April 8, 2009 The following minimum foundation recommendations for medium expansive (Expansion Index less than 91) bearing soils, classified using the "Unified Soil Classification System" or "USCS" as SM, with minimal indicated fill differential depth of should be adhered to, and incorporated into the foundation plans. Foundation plans and details may be submitted to our office for review, to insure conformance with our recommendations; Continuous strip stem wall foundations and turned-down footings should be a minimum of 24-inches deep measured below the lowest adjacent ground surface not including the sand under the slab. Continuous strip foundations should have a minimum width of 12- inches for one story and 15-inches for two story structures. Spread pad footings should be at least 24-inches square and 18-inches deep, for one and two story structures. Exterior continuous foundations or turned-down footings should enclose the entire building perimeter. Continuous interior and exterior stem wall fOundations should be reinforced with a minimum of four #4 reinforcing bars. Place two bars 3-inches below the top of the stem, and the other two bars 3-inches above the bottom of the footing. Turned-down footings should be reinforced with a minimum of two #4 bars top and two #4 bars at the bottom. Reinforcement for spread pad footings should be designed by the project structural engineer. Foundations where the surface of the ground slopes more than 1-unit vertical in 10-units horizontal (10% slope), shall be level or shall be stepped so that both top and bottom of such foundation are level. Individual steps in continuous footings shall not exceed 18- inches in height and the slope of a series of such steps shall not exceed 1-unit vertical to• 2-units horizontal (50%) unless otherwise specified. The steps shall be detailed on the structural drawings. The local effects due to the discontinuity of the steps shall also be considered in the design of foundations as appropriate and applicable. Open or backfllled trenches parallel with a footing shall not be below a plane having a downward slope of 1 unit vertical to 2 units horizontal (50%) from a line 9-inches above the bottom edge of the footing, and not closer than 18-inches from the face of such footing. Where pipes cross under footings, the footings shall be specially designed. Pipe sleeves shall be provided where pipes cross through footings or footing walls and sleeve clearances shall provide for possible footing settlement, but not less than 1-inch all around the pipe. All interior slabs should be a minimum of 5-inches in thickness reinforced with #3 reinforcing bars spaced 18-inches on center each way, placed midheight in the slab. Use VINJE & MIDDLETON ENGINEERING, INC. • 2450 Auto Park Way Escondido, California 92029-1229 • Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 5 Daybreak Community Church of Coastal North County . April 8, 2009 4-inches of clean sand (SE 30 or greater) beneath all slabs. A well performing moisture/vapor retardant (I 0-milor greater) must be placed midheight in the sand. Joints in the moisture/vapor retardant should be overlapped a minimum of 12-inches. The project architect should review the moisture requirements of the proposed flooring system and incorporate an appropriate level of moisture protection as part of the floor covering design. Provide re-entrant (±270° corners) reinforcement for all interior slabs as generally shown on the enclosed "Isolation Joints and Re-Entrant Corner Reinforcement" detail. Re- entrant corners will depend on slab geometry and/or interior column locations. The clayey soil should not be allowed to dry before pouring the concrete. The soil should be 3% to 5% above the optimum moisture content at 18 inches below slab subgrade. This office should be notified 72 hours prior to pouring the footings and slab to inspect the footing trenches and to verify the moisture conditions. Provide "soft-cut" contraction/control joints consisting of sawcuts spaced 10-feet on center maximum each way for all interior slabs. Cut as soon as the slab will support the weight of the saw, and operate without disturbing the final finish, which is normally within 2-hours after final finish at each control joint location, or when the compressive strength reaches 150 to 800 psi. The "soft-cut" must be a minimum of 1-inch in depth and must not exceed 1 'h-inch in depth or the reinforcing may be damaged. Anti-ravel skid plates should be used and replaced with each blade to avoid spafling and raveling. Avoid wheeled equipment across cuts for at least 24-hours. C. Soil Design Parameters The following soil design parameters are based upon the on site soils used during the grading of the building pad: Use a friction angle of 33 degrees. Use a wet density of 118.0 pcf. Use a coefficient of friction of 0.35 for concrete on compacted soils. Use an active pressure of 35 pcf equivalent fluid pressure for cantilever, unrestrained walls with level backfill surface. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Auto Park Way' Escondido, California 92029-1229 • Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 6 Daybreak Community Church of Coastal North County April 8, 2009 Use an active pressure of45 pcf equivalent fluid pressure for cantilever unrestrained walls with a 2:1 (horizontal to vertical) backfill. Use an at rest pressure of 56 pcf equivalent fluid pressure for restrained walls. Use a passive resistance of 384 pcf equivalent fluid pressure for level condition at the toe. Use an allowable foundation pressure of 2,000 psf for minimum 12-inch wide by 24-inch deep footings. Use an allowable lateral bearing pressure of 100 psf per foot for all structures except retaining walls. Notes: Use a minimum safety factor of 1.5 for wall overturning and sliding stability. Because large movements must take place before maximum passive resistance can be developed, a safety factor of 2.0 may be considered if sensitive structures or improvements are planned near or adjacent to the top of the wall. When combining passive and frictional resistance, the passive component should be reduced by one-third. The allowable soil bearing pressure provided herein was determined for footings having a minimum width of 12-inches and a minimum depth of 24-inches below the lowest adjacent ground surface. This value may be increased 20% for each additional foot of depth, and 10% for each additional foot of width to a maximum of 4,500 psf, if needed. The allowable soil bearing pressure provided herein is for dead plus live loads and may be increased by one-third for wind and seismic loading. The lateral bearing earth pressures may be increased by the amount of the designated value for each additional foot of depth to a maximum of 1,500 pounds per square foot. These values are for the tested on site soils only. Additional testing and recommendations will be required for any new or import soils that are not tested and approved. D. Seismic Ground Motion Values For design purposes, site specific seismic ground motion values were determined in accordance with the California Building Code (CBC). The following parameters are VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Auto Park Ways Escondido, California 92029-1229 'Phone (760) 7434214 Update Compaction Report, Proposed 2-Story Building Addition Page 7 Daybreak Community Church of Coastal North County April 8, 2009 consistent with the indicated project seismic environment and our experience with similar earth deposits in the vicinity of the project site, and may be utilized for project design work. Site Class I Ss I si I Fa I Fv I SMs I SM1 I SDs I SD1 B 1.189 0.449 1 1 1.489 0.449 0.793 0.299 According to Chapter 16, Section 1613 of the 2007 California Building Code. I Explanation: Ss: Mapped MCE, 5% damped, spectral response acceleration parameter at short periods. Si: Mapped MCE, 5% damped, spectral response acceleration parameter at a period of!- second. Fa: Site coefficient for mapped spectral response acceleration at short periods. Fv: Site coefficient for mapped spectral response acceleration at i-second period. SMs: The MCE, 5% damped, spectral response acceleration at short periods adjusted for site class effects (SMS = FaSs). SM!: The MCE, 5% damped, spectral response acceleration at a period of! -second adjusted for site class effects (SM! = FvS i). SDs: Design, 5% damped, spectral response acceleration parameter at short periods (SDs = %SMs). SD!: Design, 5% damped, spectral response acceleration parameter at a period of! -second (SD! = %SM!). Liquefaction and seismically induced settlements will not be factors in the development of the proposed structures and improvements. E. Paving and Concrete Improvements Not Within The Public or Private Street Right of Way 1. Exterior Flatwork Adjacent to Buildings: a) Exterior flatwork (walkways, and patios) must be a minimum of 4-inches in thickness reinforced with 6x6/! Ox! 0 welded wire mesh carefully placed 2-inches below the top of the slab. Provide "tool joint" or "soft cut" contraction/control joints spaced 10- feet on center (not to exceed 12-feet maximum) each way within 24-hours of concrete pour. Slab reinforcements should extend through the construction (cold) joints. In construction practices where the reinforcement is cut at the construction joints, slab panels should be tied with minimum 18-inch long #3 dowels (dowel baskets) at 18- VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Auto Park Ways Escondido, California 92029-1229 0 Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 8 Daybreak Community Church of Coastal North County April 8, 2009 inches on center maximum, placed mid-height in the slab (9-inches on either side of the joint). The slabs should also be tied to the adjacent curbs where they occur, with #3 dowels at 18-inches on center. The concrete should be placed over 6-inches subgrade compacted to a minimum of 90% of ASTM 1557. The construction procedures for tool joint or soft cut contraction/control joints are described in Item #A-9 above. Exterior slabs supported on potentially expansive soils may be subject to movements especially in the event as-grade moisture contents are not uniformly maintained during the post construction periods. In order to enhance performance of exterior flatwork supported on expansive soils, it is recommended that a minimum of an 8-inch wide by 12-inch deep "thickened" slab edge, reinforced with a minimum of one #4 reinforcing bar placed near the bottom, be placed along the slab free edges. Exterior slabs placed against the perimeter footings should be doweled to the footing using #3 reinforcing bars spaced 18-inches on center, extending 20-inches into the slab at mid-height, and into the footing to the elevation of the bottom reinforcing bar. The clayey soil should not be allowed to dry before pouring the concrete. The soil should be 3% to 5% above the optimum moisture content within the upper 12-inches of the subgrade prior to placement of the concrete. 2. Concrete driveways and parking areas should consist of 5-inch thick concrete reinforced with #3 reinforcing bars spaced 18-inches on center each way placed 2-inches below the top of the slab. The concrete should be placed over 4-inches Caltrans Class 2 aggregate base compacted to 95% over 6-inches subgrade compacted to a minimum of 90% of ASTM 1557. Provide "tool joint" or "soft cut" contraction/control joints spaced 10-feet on center (not to exceed 12-feet maximum) each way within 24-hours of concrete pour. The construction procedures for tool joint or soft cut contraction/control joints are described in Item #A-9 above. Slab reinforcements should extend through the construction (cold) joints. In construction practices where- the reinforcement is cut at the construction joints, slab panels should be tied with minimum 18-inch long #3 dowels (dowel baskets) at 18-inches on center maximum, placed mid-height in the slab (9-inches on either side of the joint). The slabs should also be tied to the adjacent curbs where they occur, with #3 dowels at 18-inches on center. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Auto Park Ways Escondido, California 92029-1229 • Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 9 Daybreak Community Church of Coastal North County April 8, 2009 Joints shall intersect free-edges at 900 angle and shall extend straight for a minimum of V/2-feet from the edge. The minimum angle between any two intersecting joints shall be 80°. Align joints of adjacent panels. Also, align joints in attached curbs with joints in slab panels. Provide adequate curing using approved methods (curing compound maximum coverage rate = 200 sq. ft./gal.). Asphalt concrete (AC) parking areas should consist of 3-inches AC over 6-inches Caltrans Class 2 aggregate base compacted to a minimum of 95% over 12-inches subgrade compacted to a minimum of 95% of ASTM 1557. Sub and basegrade soils should not be allowed to dry out or become saturated prior to placement of concrete or asphalt. Subgrade and basegradé soils shall be tested for proper moisture and compaction levels just prior to placement of the improvements. Proper drainage must be maintained at all times so that no water from any source is allowed to infiltrate the sub or basegrade soils, or deterioration of the improvements may occur. F. Geotechnical Observation/Documentation This office is to be notified no later than 2 p.m: on the day before any of the following operations begin to schedule appropriate testing and/or observation/documentation: 1. Foundations and Utility Trenches Beneath Building Slabs: If required by the governing agency, this office should be notified to document or test the following prior to foundation concrete pours: Observe the plumbing trenches beneath slabs alter the pipes are laid and prior to bacidilling. Test the plumbing trenches beneath slabs for minimum compaction requirements prior to sand and moisture barrier placement. Observe the bottom of the footing trenches for proper embedment into firm compacted or formational soils, and Observe for proper footing width prior to placement of reinforcing steel. VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Auto Park Way' Escondido, California 92029-1229 0 Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 10 Daybreak Community Church of Coastal North County April 8, 2009 d) Document the footing reinforcement size and placement. Document the slabs for proper thickness, reinforcing placement and size, document the sand thickness and moisture barrier placement and thickness, after the initial footing embedment and width documentation, and prior to concrete pour. 2. Grading - Improvements - Utility Trenches, Etc. a) Fill placed under any conditions 12-inches or more in depth, to include: Building pads. Street improvements, sidewalks, curbs and gutters. Utility trench backfills. Retaining wall backfills. The spreading or placement of soil obtained from any excavation (spoils from footings, underground utilities, swimming pools, etc.). Observation and testing of subgrade and basegrade beneath driveways, patios, sidewalks, etc., prior to placement of pavement or concrete. Moisture testing. Any operation not included herein which requires our testing, observation, or documentation for submittal to the appropriate agencies. G. Setbacks Footings located on or adjacent to the top of slopes should be extended to a sufficient depth to provide a minimum horizontal distance of 7-feet or one-third ofthe slope height, whichever is greater (need not exceed 40-feet maximum) between the bottom edge ofthe footing and face of slope. Reinforcement for deepened footings should be provided by the project structural engineer and detailed on the approved foundation plans. This requirement applies to all improvements and structures including fences, posts, pools, spas, etc. Concrete and AC Improvements should be provided with a thickened edge to satisfy this requirement. H. Slopes 1. All slopes should be landscaped with types of plants and planting that do not require excessive irrigation. Excess watering of slopes should be avoided. Slopes left unplanted VINJE & MIDOLETON ENGINEERING, INC. 0 2450 Auto Park Ways Escondido, California 92029-1229 • Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 11 Daybreak Community Church of Coastal North County April 8, 2009 will be subject to erosion. The irrigation system should be installed in accordance with the governing agencies. Water should not be allowed to flow over the slopes in an uncontrolled manner. Until landscaping is fully established, plastic sheeting should be kept accessible to protect the slopes from periods of prolonged and/or heavy rainfall. Berms should be constructed along the top edges of all fill slopes. In no case should water be allowed to pond or flow over slopes. Brow ditches should be constructed along the top of all cut slopes sufficient to guide runoff away from the building site and adjacent fill slopes prior to the project being completed. I. Drainage The owner/developer is responsible to insure adequate measures are taken to properly finish grade the building pad after the structures and other improvements are in place so that the drainage waters from the improved site and adjacent properties are directed away from proposed structures in accordance with the designed drainage patterns shown on the approved plans. A minimum of 2% gradient should be maintained away from all foundations. Roof gutters and downspouts should be installed on the building, all discharge from downspouts should be led away from the foundations and slab to a suitable location. Installation of area drains in the yards should also be considered. Planter areas adjacent to foundations should be provided with damp/water proofing, using an impermeable liner against the footings, and a subdrainage system within the planter area. It should be noted that shallow groundwater conditions may still develop in areas where no such conditions existed prior to site development. This can be contributed to by substantial increases of surface water infiltration resulting from landscape irrigation which was not present before the development of the site. It is almost impossible to absolutely prevent the possibility of shallow groundwater on the entire site. Therefore, we recommend that shallow groundwater conditions be remedied if and when they develop. The property owner should be made aware that altering drainage patterns, landscaping, the addition of patios, planters, and other improvements, as well as over irrigation and VINJE & MIODLETON ENGINEERING, INC. • 2450 Auto Park Ways Escondido, California 92029-1229 0 Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 12 Daybreak Community Church of Coastal North County April 8, 2009 variations in seasonal rainfall, all affect subsurface moisture conditions, which in turn affect structural performance. V. GENERAL RECOMMENDATIONS The minimum steel reinforcement provided herein is based on soil characteristics only, and is not intended to be in lieu of reinforcement necessary for structural considerations. The concrete reinforcement recommendations provided herein should not be considered to preclude the development of shrinkage related cracks, etc.; rather, these recommendations are intended to minimize this potential. If shrinkage cracks do develop, as is expected from concrete, reinforcements tend to limit the propagation of these features. These recommendations are believed to be reasonable and in keeping with the local standards of construction practice. Special attention should be given to any "re-entrant" corners (±270 degree corners) and curing practices during and after concrete pour in order to further minimize shrinkage cracks. It should be noted that the characteristics of as-compacted fill may change due to post- construction changes from cycles of drying and wetting, water infiltration, applied loads, environmental changes, etc. These changes can cause detrimental changes in the fill characteristics such as in strength behavior, compressibility behavior, volume change behavior, permeability, etc. The property owner(s) should be aware of the development of cracks in all concrete surfaces such as floor slabs and exterior stucco associated with normal concrete shrinkage during the curing process. The features depend chiefly upon the condition of concrete and weather conditions at the tome of construction and do not reflect detrimental ground movement. Hairline stucco cracks will often develop at windows/door corners, and floor surface cracks up to 1/8-inch wide in 20 lineal feet may develop as a result of normal concrete shrinkage (according to the American Concrete Institute). E The amount of shrinkage related cracks that oácur in concrete slab-on-grades, flatwork and driveways depend on many factors, the most important of which is the amount of water in the concrete mix.. The purpose of the slab reinforcement is to keep normal concrete shrinkage cracks closed tightly. The amount of concrete shrinkage can be minimized by reducing the amount of water in the mix. To keep shrinkage to a minimum, the following should be considered: 1. Use the stiffest mix that can be handled and consolidated satisfactorily. VINJE & MIDDLETON ENGINEERING, INC. • 2450 Auto Park Way a Escondido, California 92029-1229 • Phone (760) 743-1214 Update Compaction Report, Proposed 2-Story Building Addition Page 13 Daybreak Community Church of Coastal North County April 8, 2009 Use the largest maximum size of aggregate that is practical, for example concrete made with 3/8-inch maximum size aggregate usually requires about 40-pounds (nearly 5 gallons) more water per cubic yard than concrete with 1-inch aggregate. Cure the concrete as long as practical. The amount of slab reinforcement provided for conventional slab-on-grade construction considers that good quality concrete materials, proportioning, craftsmanship, and control tests where appropriate and applicable are provided. Where present, clayey deposits are subjected to continued swelling and shrinkage upon wetting and drying. Maintaining a uniform moisture during the post construction periods is essential in the future performance of the site structures and improvements. All retaining walls should be provided with a drain along the backside as generally shown on the enclosed "Retaining Wall Drain" detail. Specific drainage provisions behind retaining wall structures must be inspected by this office prior to backflhling the wall. All backfill soils must be compacted to a minimum of 90% of the corresponding maximum dry density, ASTM 1557. The planting of large trees behind any retaining wall will adversely affect their performance and should be avoided. Expansive soils should not be used for backfihling of any retaining structure. All retaining walls should be provided with a 1:1 wedge of granular, compacted backfill measured from the base of the wall footing to the finished surface. All underground utility trenches beneath interior and exterior slabs 12-inches or more in depth shall be compacted by mechanical means to a minimum of 90% of the maximum dry density of the soil, unless otherwise specified. Care should be taken not to crush the utilities or pipes during the compaction of the trench backfill. Trench backfill materials and compaction shall also conform to the requirements of governing agencies and authorities, as applicable. VI. LIMITATIONS Our description of grading operations, as well as observations and testing services herein, have been limited to those grading operations performed periodically from July 25, 2001 through August 13, 2001. The conclusions contained herein have been based upon our obiervations and testing as noted. No representations are made as to the quality or extent of materials not observed and tested. VINJE & MIDDLETON ENGINEERING, INC. 0 2450 Auto Park Way Escondido, California 92029-1229 0 Phone (760) 743-1214 RMV/SMSS/mpr Distribution: Thane, Timeless Architecture (6) Update Compaction Report, Proposed 2-Story Building Addition Page 14 Daybreak Community Church of Coastal North County April 8, 2009 This report is issued with the understanding that the owner or his representative is responsible to ensure that the information and recommendations are provided to the project architect/structural engineer so that they can be incorporated into the plans. Necessary steps shall be taken to ensure that the project general contractor and subcontractors carry out such recommendations during construction. The project soil engineer should be provided the opportunity for a general review of the projects final design plans and specifications in order to ensure that the recommendations provided in this report are properly interpreted and implemented. The project soils engineer should also be provided the opportunity to field verify the foundations prior to placing concrete. If the project soil engineer is not provided the opportunity of making these reviews, he can assume no responsibility for misinterpretation of his recommendations. This report should be considered valid for permit purposes for a period of six months and is subject to review by our firm following that time. IF ANY CHANGES ARE MADE, PAD SIZE, BUILDING LOCATION, ELEVATIONS, ETC., THIS REPORT WILL BECOME INVALID AND FURTHER ENGINEERING AND RECOMMENDATIONS WILL BECOME NECESSARY. If you have any questions or need clarification, please contact this office at your convenience. Reference to our Job #09-159-F will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you. VINJIE & MLDDLETON ENGINEERING, INC. mpr\my filesgrading department projectsO9-159-f daybreak community church bldg addition\update compac lion report for 2-story building addition VINJE & MIDDLETON ENGINF.ERINc., INC. 0 2450 Auto Park Way 0 Escondido, California 92029-1229 • Phone (760) 743-1214