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Home My WebLink AboutTR 31920 REC CENTER GEOTECHNICAL REPORT UPDATE ll l k-r SoilWorks Earth Sciences Group 350 Fischer Avenue Costa Mesa, CA 92626 T: 714-668-5600 www.soilworksinc.com McMillin Land Development May 29, 2013 P.O. Box 85104 Project No. 118-003-01 San Diego, CA 92106 Attention: Mr. Don Mitchell Senior Vice President Subject: Geotechnical Report Update Parcel 19 — Recreation Center Tract 31920 Summerly Development City of Lake Elsinore, California References: See attached List of Selected References Dear Mr. Mitchell: Pursuant to your request, SoilWorks, Inc. has prepared this geotechnical report update for the proposed recreation center on Parcel 19 of the Summerly development site. This report update is based on review of the referenced documents prepared by Neblett & Associates, Inc., recent field reconnaissance, and our knowledge and experience with the geologic / geotechnical aspects of the Summerly development. The Precise Grade Plan prepared by Wilson Mikami Corporation was used as a basis in developing the recommendations presented herein. PROJECT BACKGROUND Rough grading for Parcel 19 was performed as part of the mass grading for the Phase 2 Summerly Development in 2005-2006 under the observation and testing of former Neblett & Associates, Inc. (NA) and reported in Reference Nos. 2 and 3. Parcels 19 and SW McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 2 of 24 Summerly Development City of Lake Elsinore, California adjacent Parcel 18 were rough graded as a "superpad". The location of Parcel 19 within the Summerly Development site is shown on attached Figure 1 — Composite Tract Map. Mass grading for this parcel included the removal of near surface weathered, disturbed or otherwise unsuitable materials and placement of approximately 18 to 25 feet (maximum) of engineered compacted fill beneath this parcel to achieve rough grade elevations. This pad was graded with surface drainage generally trending towards Diamond Drive. Preliminary foundation recommendations were provided by NA in Reference No. 3 for residential construction. Recommendations specific to the park site (Parcel 19) and adjacent school site (Parcel 18) were not included, pending formulation of project concepts and details. PROJECT DESCRIPTION The planned development will include swimming pool complex (large and small pool, spa and associated decking) and restroom facilities on the northerly portion of this parcel, recreation building and lawn turf areas on the westerly and central portion of this parcel, and paved asphalt paved access drives and parking areas on the easterly and southerly portions of this parcel. CURRENT SITE CONDITIONS To date, this parcel remains undeveloped, and the parcel surface supports a minor regrowth of weeds / grasses (see Photo 1) and exhibits weathering and erosion. Moderate to severe erosion gullying was observed along the slope adjacent to Diamond Drive on the westerly (see Photo 2), and temporary rip rap has been placed within some of these gullies (see Photo 3) to limit further erosion. A cavity resulting from apparent soil piping was exposed approximately 2-3 feet below the top of slope within one of these erosion gullies (see Photo 4). A rodent burrow was noted approximately 10 feet back of slope and approximately 20 feet away from this observed cavity and appears to be the source of this soil piping. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical ReportUpdate Project No. 11 1 Parcel • — Recreation C- - • 1 '_•- 3 of Surnmerly Development City o - Elsinore, California s, 411 Photo 2 — Erosion Gullying Aong Diamond Drive r • �-:.. � tv ,};,-•sir- �f..ff°�� 1 fir. 1y^�yr� i t•' +~' C Lr'L l f . !� r SoHWorks EarthSciences • • McMillin • Development May 2• Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 4 of 24 Summerly Development City of - Elsinore, California Photo 3 — Rip-Rap Infilled Erosion Gully along Diamond Drive Photo 4 — Soil Piping Cavity Erosion Gully Along Diamond Drive SoilWorks Earth '.1 ,.. 1��.�•�3� � Ste, - riJ•�•.h.cL�tyr•. ! is .�� - � - - _ - ��,`._ •_,� oyfo, .. ++ .t p:1. �•, ^�..�- •�! �`d ' ,' � Ott ,- � • � - v ,� :. ''MAC r. 3�+ _ �.� � .--ter. �-� % ti }..� •��' - Sciences McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 5 of 24 Summerly Development City of Lake Elsinore, California In order to remediate the soil subgrade surface of the subject parcel to previously approved rough grade conditions acceptable for re-certification purposes, it will be necessary to recondition the existing pad surface and repair / reconstruct perimeter slopes bordering this parcel as recommended below. RECOMMENDATIONS Remedial Grading Presented below are general recommendations for use in pad reconditioning and slope repair / reconstruction for the subject site for pad re-certification purposes and provide acceptable support for the planned recreation center development. Pad Reconditioning • Prior to pad reconditioning as recommended below, existing surface vegetation and miscellaneous debris, if present, should be stripped and disposed off off-site. Existing rodent burrow location(s) / soil piping zones / cavities should be identified and flagged in the field and chased out and removed prior to pad reconditioning operations. • Pad reconditioning should, as a minimum, consist of scarification of the exposed pad surface to a minimum depth of about 8 inches, scarified soils moisture- conditioned to approximately 1 to 2 percentage points wet of optimum moisture conditions, and recompacted to at least 90 percent relative compaction (ASTM D:1557). Depending on the soil conditions observed at the time of pad reconditioning, it may be desirable to pre-wet the exposed subgrade soils in advance of scarification and recompaction efforts. • Any disturbed/weathered soils, if found to extend below the recommended scarification depths, should be removed full depth, and the underlying competent subgrade soils scarified and recompacted as recommended above prior to the replacement of acceptable materials and engineered compacted fill. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 6 of 24 Summerly Development City of Lake Elsinore, California • Additional fills, if required to achieve finish grades, should consist of material similar to the on-site soils, and be placed and compacted as recommended in the following "General" section. Slope Repairs / Reconstruction • Loose and disturbed material generated from the slope washout should be completely removed exposing the underlying competent compacted fill. The removal of this material would best be accomplished with an excavator or backhoe. • Temporary back-cut slopes during removal of loose/disturbed material should be made no steeper than 1:1 (horizontal to vertical). Final temporary back cut slopes will be dependent upon the soil conditions encountered, construction procedures and schedule. Temporary back-cuts should not to be left open for extended periods of time. The grading should be coordinated to complete removals in a timely manner and place compacted fill as quickly as possible subsequent to the approval of the removal bottom and keyway. • New fill placements should be keyed at the base of slope, as appropriate, and benched into the excavation sides as fill placement progresses. The location of benches and any keyways will be directed in the field by our office based on the slope repair configurations and conditions exposed. • Approved fill materials should be placed in thin horizontal lifts as recommended in the following General Section. • The fill slope face should be over-built and trimmed back to finish slope gradient or constructed to finish slope gradient and compacted by track-walking. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 7 of 24 Summerly Development City of Lake Elsinore, California General • The acceptability of scarification and recompaction of the exposed surface should be substantiated by the Project Geotechnical Engineer or his representative at the time of pad reconditioning, and prior to placing additional fills, if required to achieve finish pad grade elevations. • If it is determined during grading that site soils require over-excavation to greater depths for obtaining proper support for new fill placement and structures, this additional work should be performed in accordance with the recommendations of the Project Geotechnical Engineer or his representative. • Approved excavation bottoms should be moisture-conditioned, as necessary, to approximately 1 to 2 percentage points wet of optimum moisture content, scarified to a minimum depth of 6 inches and compacted to minimum 90 percent of the laboratory maximum dry density (ASTM: D 1557). • Approved fill materials should be placed in lifts not exceeding 6 to 8-inches in loose thickness, moisture-conditioned to approximately 1 to 2 percentage points wet of optimum moisture content and compacted to minimum 90 percent relative compaction, based on the laboratory maximum dry density (ASTM: D 1557). All grading should be performed under the observation and testing of the Project Geotechnical Engineer or his representative. • Immediately prior to construction, the subject lots should be re-evaluated by a representative of our office for acceptability. Foundation Design Criteria Presented below are preliminary recommendations for the design and construction of conventional footings and post-tensioned slab foundations which may be considered for planned recreation facility structures. Soi!Works Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 8 of 24 Summerly Development City of Lake Elsinore, California Conventional Foundations The planned recreation facility structures may be supported on conventional continuous and spread footings bearing on compacted engineered fill. For potential low soil expansion, continuous and spread footings may be designed based on the following criteria: Allowable Bearing Pressure (1) = 1,500 psf Minimum Footing Depth (2) = 18 inches Minimum Footing Width = Per 2010 CBC Passive Soil Pressure (3) = 250 psf/ft., subject to a maximum of 2,000 psf Friction Coefficient = 0.35 (ultimate) Minimum Footing Reinforcement = For continuous footings, min. two No. 4 bars, one at top and one at bottom. (1) The above value may be increased 250 lbs./sq.ft. for each additional foot exceeding the minimum embedment depth, subject to a maximum of 2,500 psf. Allowable bearing pressures may be increased by one-third for short term loading due to wind or seismic forces. (2) Footing depth is below lowest adjacent soil grade. (3) Passive soil pressure value is for level soil conditions adjacent to footings. Post-Tensioned Slab / Footings As an alternate to conventional foundations, post-tensioned slab foundation systems may be preferable to conventional foundations / slabs and offer the following advantages: ® Post-tensioned slabs can provide additional foundation and slab rigidity and help in mitigating potential effects due to differential soil movement resulting from settlement and soil expansion. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 9 of 24 Summerly Development City of Lake Elsinore, California • Some residential developers have recently opted for post-tensioned slab/footing design on some sites without consideration of existing on-site soil conditions, stating that construction of post-tension slabs are less labor intensive. • Some developers prefer post-tensioned slabs due to the higher degree of quality control (e.g. concrete inspector required, etc.). Also, cracking development as a result of concrete shrinkage tends to stay closed longer. The Owner and Project Civil/Structural Engineer should evaluate the suitability of such a foundation system for the project site conditions and needs. Post-tensioned slab footings may be designed in accordance with either the California Spannability method or PTI procedures. Presented below are preliminary geotechnical criteria for post-tensioned slab/footings based on the "Design of Post-Tensioned Slabs- On-Ground (Third Edition with 2008 Supplement) by the Post-Tensioning Slab Institute and conservatively based on low soil expansion: Thornthwaite Moisture Index -20 Constant Suction (pF) 3.9 Center Lift Condition Edge Moisture Variation Distance, em 9.0 feet Differential Swell, ym 0.24 inches Edge Lift Condition Edge Moisture Variation Distance, em 5.3 feet Differential Swell, ym 0.61 inches Minimum Depth of Footings 12 inches (perimeter) Slab Thickness Per Structural Engineer Sub-grade Pre-saturation Presoak or maintain a soil moisture condition of approx. 1-3 percentage points above the optimum moisture content to a depth of 12 inches SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 10 of 24 Summerly Development City of Lake Elsinore, California Note: The above design parameters are based on climatic conditions only, and are applicable for sites with proper site drainage, landscaping and irrigation, and adequately maintained as addressed hereinafter. General Foundation Remarks a) Foundation details such as concrete strength, reinforcements, etc. should be established by the Project Structural Engineer, considering the low soil expansion potential and loading and service conditions. The reinforcements provided should be considered as minimum requirements. b) Isolated column footings should be tied together by grade beams in at least two (2) orthogonal directions. c) Foundation excavations should be observed and approved by the Project Geotechnical Engineer prior to the placement of reinforcement or concrete. Forming of footing excavations may be required. Excavations should be free of slough and debris and thoroughly moisture conditioned prior to placing concrete. d) Excavated materials from footings and utility trenches should not be placed in slab-on-grade areas unless properly compacted and tested under the observation and testing by the geotechnical engineer. e) Footing depths should not be allowed to be affected adversely, such as through erosion, softening, digging, landscaping, etc. f) Where foundations encroach closer than five (5) feet horizontally from the flow line of drainage swales, the footing should be deepened sufficiently to maintain the required embedment depth below the adjacent flow line. g) Exposed footing excavations and slab subgrade soils should be pre-soaked and/or maintained at a soil moisture condition of 1-3 percentage points wet of optimum moisture content to a depth of at least 12 inches. SoHWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 11 of 24 Summerly Development City of Lake Elsinore, California Structure Movement Some structure movement should be expected both during and following construction, even when supported on engineered compacted fill, due to various factors including, but not limited to: • Sequence of foundation and slab loading during construction; • Variation in structural loads along foundation elements; • Variation in underlying soil types with different compressibility indices and subsurface soil profile, and associated primary and long-term secondary consolidation settlements; • Moisture changes due to climatic and non-climatic influences following construction, and associated shrink/swell of expansive soils; It should also be recognized that given residential construction tolerances, concrete floor slabs will not be cast perfectly level, and it has been our experience that floors slab elevations across a residence may vary by as much as an inch or more. For design purposes and considering the above factors, static settlements for continuous and spread footings designed in accordance with the above recommendations and for structural loading typical for the residential-type construction (column and wall loads not exceeding 30 kips and 3 kips/lineal foot, respectively) are not anticipated to exceed 1-inch total. In addition, differential movement between similarly loaded adjacent column footings and for continuous footings and slabs over a distance of 30 feet are not expected to exceed 3/4 inch. The potential differential movement for slabs specified above does not include potential deformations as a result of subgrade responses to seasonal and other moisture variation and expansive soils phenomena, which may exceed the above specified values. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 12 of 24 Summerly Development City of Lake Elsinore, California Seismic Design Considerations The site, as is all of southern California, is within a zone of seismic activity. Strong ground motion from an earthquake generated along active faults should therefore be anticipated at this site. The proposed development should be designed and constructed to the prevailing seismic design standards. Seismic design should be based on current and applicable CBC requirements, as appropriate. The 2010 CBC (ASCE 7-05) Seismic Design Parameters are presented in Appendix A. Slab on Grade For design purposes, concrete floor slabs should be designed to resist potential expansive soil pressures and structural and/or construction loading considerations. The slab design and construction details should be established by the Project Design Engineer. From a geotechnical standpoint, the minimum criteria for slab-on grade are shown below: a) Concrete Floor Slabs for Conventional Foundation Construction Concrete floor slabs should be 4 inches thick (minimum) and should be reinforced with No. 3 bars at 18 inches on center, each way at mid height. No. 3 bars at 18 inches on center should be provided connecting floor slabs to footings. In order to minimize migration of moisture up the concrete slab from soil sub- grade and damage to floor coverings, a moisture barrier/water vapor retarder system should be placed beneath floor slabs as recommended hereinafter. d) Exterior Flatwork Sidewalks and walkways should be 4 inches thick (minimum). Hardscape areas within two feet of the descending slopes should include a thickened edge deepened to provide a minimum five (5) feet horizontal setback between the bottom outside face of the thickened edge and slope face. SoitWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 13 of 24 Summerly Development City of Lake Elsinore, California c) Slab Sub-grade Pre-saturation Prior to concrete placement, the prepared soil sub-grade should be moisture conditioned to and maintained at about 1 to 3 percentage points wet of optimum moisture contents to a depth of 12 inches and exhibit at least 90 percent relative compaction as determined by ASTM: D1557. d) General Flatwork Remarks • Interior floor slabs and exterior concrete flatwork should be properly designed for the construction and service loading conditions, and potential differential movements. The structural details, such as slab thickness, concrete strength, reinforcing criteria, joint spacing, etc. should be established by the Project Civil / Structural Engineer. The recommended minimum reinforcements for concrete slabs provided above are intended for preliminary design only. More restrictive criteria as dictated by structural design or regulatory requirements shall govern. • All reinforcement must be appropriately spaced and supported/maintained during the pouring/finishing work such that it remains in proper condition. • Unless specifically allowed for and approved as such by the project Civil Engineer, no water is to be added to the concrete mix after the truck leaves the plant. It should be cautioned that addition of water to the concrete mix will change the water-cement ratio of the plant design mix and can lead to undesirable shrinkage cracking, curling, etc. of concrete slabs during curing. • All concrete to be properly finished per American Concrete Institution / Portland Cement association standards and moist cured (for preferably at least 7 days). If moist curing is not feasible, an appropriate curing compound / sealant should be applied in accordance with the timing and methodology specified by the curing compound manufacturer. SoiiWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 14 of 24 Summerly Development City of Lake Elsinore, California • Truck tickets to include mix design, time leaving plant, time of site arrival, and time onsite / location of pour to be documented and copies sent to the project engineer. • All poured concrete should be protected from loading and traffic for at least 7- days without written approval of the project engineer. Moisture /Water Vapor Retarder for Concrete Slab-on-Grade In order to reduce the potential for moisture/water vapor migration up through the slab and possibly affecting floor covering, a moisture/vapor retarder is recommended under concrete floor slab-on-grade. As a minimum, this moisture/water vapor retarder should consist of high strength polyethylene membrane meeting or exceeding the ASTM: E-1745-97 Class C material requirements for water vapor permeance, tensile strength and puncture resistance, be properly lapped and sealed, and placed mid-height within a 4-inch coarse sand layer. Based on our review of available literature, it appears that the guidelines by the American Concrete Institute (ACI [April 2001]) to reduce the potential moisture/water vapor intrusion in concrete slab-on-grade would be more effective to help reduce potential moisture/water vapor migration up through concrete slab-on-grade and should be considered. The recommendations provided below are based on the guidelines of the American Concrete Institute (ACI Committee Report 302.1 R-96): • The moisture/water vapor retarder should consist of high strength polyethylene membrane and should meet or exceed the ASTM: E-1745-97 Class C material requirements for water vapor permeance, tensile strength and puncture resistance. The vapor retarder should consist of "Moistop Plus" (Fortifiber Building Products Systems) or "Vapor Block" VB 15 (Americover, Inc.), or approved equal. The vapor retarder should be underlain by a capillary break comprised of minimum 4 inches thick pea gravel layer. The gravel layer should be placed and compacted on approved soil sub-grade. SoHWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 15 of 24 Summerly Development City of Lake Elsinore, California • The installation of the moisture/water vapor retarder system requires specialized knowledge and experience and should be accomplished with the technical assistance and supervision of retarder system manufacturer and/or supplier. The membrane should be placed on approved gravel layer and properly lapped and sealed. Membranes intersecting utility pipes, sewer lines, ducts or drains must be properly wrapped around the penetrations and sealed. All punctures and rips in the membrane should be repaired prior to placement of concrete, following manufacturer's recommendations. • The vapor retarder should be installed in general accordance with the procedures outlined in ASTM: E-1643, and in conformance with the installation procedures recommended by the manufacturer. • To minimize slab curling, a low shrinkage / low slump concrete (concrete mix with a 4,500 psi compressive strength and water cement ratio of 0.45) should be used for the slab construction, as determined by the Project Structural Engineer. The mix design should be verified by the project Civil / Structural Engineer, and placement of concrete should be observed and certified by the Concrete Deputy Inspector. • In addition, floor coverings (e.g., wood, tile, etc.) and other built-in features should be carefully selected with vapor transmission in mind, and include proper preparation and installation in accordance with the manufacturer's recommendations. It should be recognized that, even with site surface and sub-drainage measures, there is potential for saturation of ground beneath concrete floor slabs due to water infiltration from irrigation, rain, and run-off or flow through the soil subgrade. The upward migration of moisture in vapor phase from soil subgrade through the slab-on-grade is inevitable under normal living conditions as they exist within a closed environment (e.g., structure). It is imperative that the Contractor properly install the recommended site drainage measures, utility trench backfill, and the moisture/water vapor retarder system SoHWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 16 of 24 Summerly Development City of Lake Elsinore, California in accordance with the project design requirements and specifications to mitigate potential moisture / water vapor transmission into the structures. It should be emphasized that proper control of irrigation and landscape water adjacent to the structure and maintaining proper site drainage is very important to minimize problems caused by moisture and water vapor intrusion. Soil Expansion Based on laboratory test results presented in Reference No. 3, the fill soils underlying the subject tract consist predominantly of silty sands exhibiting very low soil expansion characteristics. Considerations for this potential soil expansion should be incorporated in the design and construction, as appropriate. Soil Corrosivity and Concrete The results of soluble soil sulfate tests presented in Reference Nos. 2 and 3 and Table 4.3.1 of ACI 318 Building Code (Table 4.2.1 of ACI-318-08), sulfate exposure to concrete is considered negligible (not applicable), and there are no special requirements for concrete in contact with soils. However, it has been our experience that post-construction factors such as the use of fertilizers in lawn / landscape areas, near surface soil wetting and drying cycles, etc. can increase the soluble sulfate contents and these conditions predispose them to being highly corrosive to both concrete and buried metals. Higher strength concrete with lower water / cement ratio will improve overall slab performance, durability, water and corrosivity resistance. As recommended in the "MoistureMater Vapor Retarder for Concrete Slab-on-Grade", a low shrinkage / low slump concrete (concrete mix with a 4,500 psi compressive strength and water cement ratio of 0.45) should be used for the slabs when constructed directly on the moisture water vapor retarder system. Use of admixtures in the concrete mix can enhance the workability of the concrete, reducing bleeding, facilitate finishing, and reduce potential for slab cracking during curing. For this reason, it may be prudent to use a concrete mix designed specifically for concrete floor slab application. Soi!Works Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 17 of 24 Summerly Development City of Lake Elsinore, California As a minimum, and subject to the approval of the project Civil / Structural Engineer, concrete with minimum 2,500 psi strength and maximum water.-cement ratio of 0.5 may be used for exterior hardscape construction. Laboratory tests to evaluate the potential soil corrosivity to metallic installations were not performed. In the absence of such testing, the soils along with any transient waters flowing through them should be considered to be highly corrosive to metals in contact with them. Attention to minimizing galvanic / chemical corrosivity (i.e., protective coatings, dielectric couplings, eliminating mixing metal types in contact or in near vicinity to each other) where in contact with soil and soil moisture can minimize these effects. An experienced corrosion consultant should be retained and their recommendations incorporated into the design if special / critical corrosive issues exist or further corrosion potential study is warranted. Swimming Pool Pool / Spa Design (1) Pool and spa walls should be adequately designed considering the lateral earth pressure and anticipated loading conditions during the life of the structure. For the on-site soil conditions and conservatively considering potential for hydrostatic pressures, a minimum lateral earth pressure of 90 pcf (equivalent fluid pressure) is recommended for the design of pool walls. The surcharge effects due to adjacent construction should be included in pool/spa wall design, as appropriate. (2) The pool, spa and other pool elements should be adequately designed considering low soil expansion potential and should be adequately reinforced. As a minimum, a square bond beam (minimum 12" x 12") with minimum of four No. 5 bars, two at top and two at bottom is recommended for the pool. (3) A hydrostatic relief valve should be incorporated into the specifications and placed in the bottom of pool. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 18 of 24 Summerly Development City of Lake Elsinore, California (4) Pool and spa excavations should be cleaned of all loose/sloughed materials and be neatly trimmed prior to the placement of steel and concrete. The exposed soils should be moistened periodically to maintain existing moisture conditions. Pool Deck Presented below are recommendations for the planned pool decks and patio slabs for the subject project. These recommendations consider low expansion potential, well prepared and moisture conditioned subgrade, and proper / appropriate reinforcement placement and control, and, proper/ appropriate finishing and curing. Thickness: 4" (minimum) Concrete: 2,500 psi strength with maximum water/cement ratio of 0.5. Reinforcing No 3 bars at 18 inches on center, each way, placed midheight of slab. Deck Underlainment: 4-inch layer of crushed miscellaneous base compacted to 95 percent relative compaction. Deck Edges: Deck edges adjacent to pool coping or landscape should be deepened with one foot minimum thickened edge, reinforced with two No. 4 bars, top and bottom. Joint Sealant: The interface between the pool deck and coping should include appropriate foam backing (Deck-o-Foam or equivalent) and topped with an approved water-tight sealant, installed in accordance with manufacturer's recommendations. Retaining Walls Ancillary retaining walls may be designed based on the following criteria: • Retaining wall footings supported on approved engineered compacted fill may be designed based on a maximum allowable soil pressure of 1,500 psf. The recommended minimum footing depth is 2 feet below lowest adjacent soil grade. • Retaining wall footings should be adequately designed to resist the lateral soil pressures and the anticipated construction and service load conditions. The earth pressure acting on retaining walls depends primarily on the allowable wall movement, type of backfill materials, backfill slopes, wall inclination, surcharges, SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 19 of 24 Summerly Development City of Lake Elsinore, California and any hydrostatic pressure. The following minimum lateral earth pressures are recommended for vertical cantilevered retaining walls with no hydrostatic pressure and no surcharge loading: Lateral Earth Pressure Wall Condition Backfill Slope (Equivalent Fluid Pressure) Active Case Level 40 pcf (Cantilever Walls) 2H : 1V 65 pcf The above values are applicable for walls backfilled with non-expansive, free- draining granular backfill (sands) placed between the wall and a 45 degree imaginary plane projecting upwards and outwards from the heel of the wall footing. • The surcharge effect of anticipated adjacent loads located on the wall backfill (e.g., traffic, footings) should be included in wall design. For cantilever walls, an additional lateral pressure equal to 33 percent of the maximum surcharge load located within a distance equal to the wall height should be used in design. • The wall design should include waterproofing (where appropriate) and weep holes or backdrains for relieving hydrostatic pressure. The backdrain should consist of perforated Schedule 40 PVC pipe, minimum 4-inch diameter, embedded in minimum 3 cubic feet / foot of gravel, and enveloped in Mirafi 140 geo-fabric or approved equal. The drain pipe should be installed as a minimum gradient of 1 percent and should discharge unto a suitable outlet. • No backfill should be placed against concrete until minimum design strengths are attained, as determined by concrete compression tests. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 20 of 24 Summerly Development City of Lake Elsinore, California Retaining wall backfill should be mechanically compacted to 90 percent (minimum) relative compaction (ASTM: D1557). No ponding, jetting or flooding should be permitted. Foundation Setbacks Structure and retaining wall foundations located adjacent to slopes should be setback laterally from the slope face in accordance with the 2010 CBC and the requirements of the City of Lake Elsinore. For minor masonry screen walls, a minimum horizontal setback of 5 feet from the outer edge of footings to the slope face may be considered. Utility Trench Backfill a) The on-site soils consist mostly of silty sandy soils and are generally considered unsuitable for use as bedding material. Bedding and shading material should consist of sandy material exhibiting a Sand Equivalent (S.E.) value of 30 or greater, be free of objectionable inclusions and fines to prohibit free flow and hydro-consolidation, and should comply with the requirements of the controlling governing jurisdiction. Adherence to these requirements is important in order to prevent bridging of soils along the sides of the utility lines, infill potential voids around the base of pipe, and provide more uniform relative compaction of materials surround the line. b) The site soils are considered suitable for trench backfill, provided they are properly processed / moisture conditioned and free of organic material and rocks over 4 inches in maximum dimension. c) To reduce potential water migration into building sub-grade through the granular bedding / shading layer and trench backfill, utility trenches crossing beneath building perimeter edges should be backfilled with the onsite finer grained materials or sand-cement slurry for minimum 3 feet length at their entry points. Utility line backfill placed below or within a SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 21 of 24 Summerly Development City of Lake Elsinore, California zone defined by a theoretical plane downwards and outwards at a 1:1 (horizontal to vertical) projection from the outside edge of footings should be compacted to a minimum 95 percent relative compaction or slurry backfilled (minimum 2 sack cement - sand mix). d) Backfill of all exterior and interior trenches should be placed in thin lifts not exceeding 4 inches and mechanically compacted to achieve a relative compaction of not less than 90% based on ASTM: D1557. Care should be taken not to damage utility lines. e) Trenches greater than 4 feet in depth should be shored or sloped back as required by the local regulatory agency, the State of California Division of Industrial Safety Construction Safety Orders, and Federal OSHA requirements. The soil and temporary excavation conditions should be evaluated on a case-by-case basis by the project geotechnical engineer / engineering geologist, using the actual conditions exposed for developing recommendations regarding such excavations. Site Drainage Of all the post-construction maintenance items — attention to site drainage is the most important as water is the cause of most problems. The Developer, Landscape Architect, and H.O.A should be aware of the potential problems that may develop when drainage is altered through construction of retaining walls, paved walkways, and patios. Conditions which will lead to ground saturation must be avoided. a) All roof and surface drainage should be directed away from structures and their appurtenances and slopes to approved drainage facilities. Ponding of water should be avoided. Per the 2010 CBC, a minimum gradient of 5 percent away from structures should be maintained for graded soil areas to a distance of 10 feet or to approved drainage swales. SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 22 of 24 Summerly Development City of Lake Elsinore, California b) The recommended drainage patterns should be established at the time of fine grading and maintained throughout the life of the structure or, if altered, should be replaced with properly designed area drain system. c) Irrigation activities at the site should be monitored and controlled to prevent over watering. Planter and lawn areas adjacent to structures should be avoided. If utilized, these should include measures to contain irrigation water and prevent moisture migration into the walls and under foundations and slabs-on-grade. d) The selection of plant palettes should be based on that which is suitable for the area and be drought tolerant. e) It is imperative that all new construction maintain positive drainage to suitable discharge facilities. Adequate area drainage systems should be installed in planter areas and within flatwork areas, as required. Landscape, Irrigation, and Maintenance General guidelines for landscape, irrigation and maintenance are shown below: (1) Landscape planting should consist of appropriate drought resistant vegetation as recommended by the Landscape Architect. Landscaping of slopes should be completed as soon as possible and properly maintained. (2) It is imperative that proper irrigation practices be implemented and installed irrigation systems be maintained. Leaks should be repaired immediately. Sprinklers should be adjusted to provide maximum coverage with a minimum of water usage and overlap. Over-watering with consequent excessive runoff and ground saturation must be avoided. (3) If automatic sprinkler systems are installed, their use should be adjusted to account for natural rainfall conditions. SoHWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Page 23 of 24 Summerly Development City of Lake Elsinore, California (4) All interceptor ditches, drainage terraces, down-drains, and any other drainage devices that have been installed must be maintained and cleaned. (5) If rodent activity is present, the property owner should undertake a program for the elimination of burrowing animals. This should be an ongoing program in order to promote slope stability. (6) Water should be directed away from constructed or natural slopes faces. This may require the construction of berms or ditches along the top of slopes, if such devices are not in place. Plan Review, Observations and Testing During the design and precise grading phases, the final Precise Grading and Foundation Plans, including the design details of planned structures (e.g., location, configuration, design loads, etc.) should be provided to the Project Geotechnical Engineer to verify the applicability of the recommendations provided above and to develop additional and/or revised recommendations, as appropriate. Precise grading, including foundation and on-site construction should be performed under the observation, documentation, and testing by the Project Geologist and Geotechnical Engineer. To document actual conditions encountered, work performed, and any in-field modifications / adjustments, an As-Graded report should be prepared upon the completion of work. CLOSURE Our review and preparation of this report are based on our experience, available documents and our knowledge of the site, and were obtained in accordance with currently accepted professional engineering principles and practice in the field of geologic and geotechnical engineering, and reflect our best professional judgment. We make no other warranty, either express or implied. This report is subject to supplementation and revision as new information becomes available and the designs SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19— Recreation Center, Tract 31920 Page 24 of 24 Summerly Development City of Lake Elsinore, California are refined. This report is also subject to the review of the City of Lake Elsinore and any comments /responses become a part hereto and to the project specifications. The recommendations provided by this firm are made on the assumption that we will be retained to perform the geotechnical onsite observation, testing and support associated with the proposed work. If another geotechnical firm is used, these and any other applicable recommendations developed by this firm are considered void. SoilWorks is not responsible for any implementation of recommendations or grading / construction that it did not have an adequate opportunity to observe, test, comment on, and document. Similarly, should unanticipated conditions be encountered or alterations to the current design be made, this office should be given the opportunity and retainage to evaluate and provide revisions / updates as warranted. We appreciate the opportunity of being of service to you on this project. Should you have any questions or need additional information, please contact the undersigned. Sincerely, SoilWorks, Inc. Q�oFESSio' S�010 Ess/o Q1 E x � . STi�c `�yc GE 2265 n n By: L � By: AkA -XP ar3,r20 4 Da iel J. on a, E. Steven E. Strickler, sT M,\�P��r RGE 2726, Re �9 ?A��9\\4 RGE 2265, Reg. expir \F� \ OF CAL1F0`�` Attachments: List of Selected References Figure 1 - Composite Tract Map 2010 CBC Seismic Design Criteria Distribution: Addressee (3) SollWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Summerly Development City of Lake Elsinore, California LIST OF SELECTED REFERENCES 1. Neblett & Associates, inc., Preliminary Geotechnical Investigation and 40-Scale Grading Plan Review, Tentative Tract 31920, Stage 2 of Summerly Development, City of Lake Elsinore, County of Riverside, California, dated February 7, 2006, Project No. 420-001-05. 2. Neblett & Associates, Inc., Interim Rough Grade Compaction Report, Parcels 18 & 19, Stage 2, Summerly Development site, Tract 31920, Lake Elsinore, California, dated august 30, 2007, Project no. 420-001-07. 3. Neblett & Associates, Inc., Rough Grade Compaction Report, Stage 2 of the Summerly Development Project, Tract 31920, Lake Elsinore, California, dated November 30, 2007, Project No. 420-001-07. 4. Summerly — McMillin DDA, Tract Map Composite Exhibit, Sheet 1 of 1, Project No. 10001.13, undated. 5. Wison Mikami Corporation, Precise Grading Plan for Summerly Recreation Center, Lot 19 of Tract 31920-1, City of lake Elsinore, State of California, Sheets 1 through 15 of 15 SoilWorks Earth Sciences Group McMillin Land Development May 29, 2013 Geotechnical Report Update Project No. 118-003-01 Parcel 19 — Recreation Center, Tract 31920 Summerly Development City of Lake Elsinore, California 2010 CBC SEISMIC DESIGN CRITERIA SoilWorks Earth Sciences Group a'vUSGS Design Maps Summary Report User-Specified Input Building Code Reference Document ASCE 7-05 Standard (which makes use of 2002 USGS hazard data) Site Coordinates 33.6460N, 117.304°W Site Soil Classification Site Class D -"Stiff Soil' Occupancy Category Occupancy Category I r, Sun City a Simpson Rd Lazy Creek %a) Canyon Recreational Lake Center Menifee I711 Lake Summerhill F Lake ElsinorePark r snore � n b r; Lakeland Village Cry �'�n'tda a,Q oa i 41 Wildomar , United Stales (l7 Y1ty .. 9- it�-Ac. Califo Park Oaks F Mexico USGS-Provided Output Ss = 1.722 g SMs = 1.722 g SoS = 1.148 g Sl = 0.620 g Smi = 0.929 g SDI = 0.620 g MCE Response Spectrum Design Response Spectrum 1.99 1.9D 1.Z0 1.63 1.09 1.44 0.96 0.72 0.9D 0.6Q 0.73 0.49 0.94 0.H6 0,85 0.$4 0.19 0.13 0.00 0.00 0.00 0.20 0.40 Q.GQ 0.00 1.00 1.20 1.40 1.60 1.90 2.00 0.00 0.20 0.40 0.60 0.90 1.00 1.20 1.40 LGQ 1.90 2.00 Period.T(sec) Period.T(sec) Although this information is a product of the U.S.Geological Survey,we provide no warranty,expressed or implied,as to the accuracy of the data contained therein.This tool is not a substitute for technical subject-matter knowledge. �$�s Design Maps Detailed Report ASCE 7-05 Standard (33.6460N, 117.304°W) Section 11.4.1 — Mapped Acceleration Parameters Maps in the 2005 ASCE-7 Standard are provided for Site Class B. Adjustments for other Site Classes are made, as needed, in Section 11.4.3. From Figure 22-1 Ell S„ = 1.722 g From Figure 22-212I S1 = 0.620 g Section 11.4.2 — Site Class SITE SOIL PROFILE Soil shear wave Standard penetration Soil undrained shear CLASS NAME velocity, vs, (ft/s) resistance, N strength, s., (psf) A Hard rock vs > 5,000 N/A N/A B Rock 2,500 < vs <_ 5,000 N/A N/A C Very dense soil 1,200 < vs <_ 2,500 N > 50 >2,000 psf and soft rock D Stiff soil profile 600 <_ vs < 1,200 15 <_ N <_ 50 1,000 to 2,000 psf E Stiff soil profile vs < 600 N < 15 <1,000 psf E — Any profile with more than 10 ft of soil having the characteristics: 1. Plasticity index PI > 20, 2. Moisture content w >_ 40%, and 3. Undrained shear strength s < 500 psf u F — Any profile containing soils having one or more of the following characteristics: 1. Soils vulnerable to potential failure or collapse under seismic loading such as liquefiable soils, quick and highly sensitive clays, collapsible weakly cemented soils. 2. Peats and/or highly organic clays (H > 10 feet of peat and/or highly organic clay where H = thickness of soil) 3. Very high plasticity clays (H > 25 feet with plasticity index PI > 75) 4. Very thick soft/medium stiff clays (H > 120 feet) For SI: 1ft/s = 0.3048 m/s 1lb/ft2 = 0.0479 kN/mz Section 11.4.3 - Site Coefficients and Adjusted Maximum Considered Earthquake (MCE) Spectral ................. Response Acceleration Parameters Table 11.4-1: Site Coefficient F a Site Class Mapped MCE Spectral Response Acceleration Parameter at Short Period SS <_ 0.25 SS = 0.50 SS = 0.75 SS = 1.00 SS >! 1.25 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.2 1.2 1.1 1.0 1.0 D 1.6 1.4 1.2 1.1 1.0 E 2.5 1.7 1.2 0.9 0.9 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of SS For Site Class = D and SS = 1.722 g, Fa = 1.000 Table 11.4-2: Site Coefficient F Site Class Mapped MCE Spectral Response Acceleration Parameter at 1-s Period S <_ 0.10 S = 0.20 S = 0.30 S = 0.40 S >_ 0.50 A 0.8 0.8 0.8 0.8 0.8 B 1.0 1.0 1.0 1.0 1.0 C 1.7 1.6 1.5 1.4 1.3 D 2.4 2.0 1.8 1.6 1.5 E 3.5 3.2 2.8 2.4 2.4 F See Section 11.4.7 of ASCE 7 Note: Use straight-line interpolation for intermediate values of S1 For Site Class = D and S, = 0.620 g, F� = 1.500 Equation (11.4-1): SMs = F SS = 1.000 x 1.722 g = 1.722 g Equation (11.4-2): SM1 = F v S 1 = 1.500 x 0.620 g = 0.929 g Section 11.4.4 — Design Spectral Acceleration Parameters Equation (11.4-3): S DS = 2/ S MS = % x 1.722 g = 1.148 g Equation (11.4-4): S DI = z/ M1 S = Z/ x 0.929 g = 0.620 g Section 11.4.5 — Design Response Spectrum From Figure 22-15[31 T = 8 seconds L Figure 11.4-1: Design Response Spectrum T<TQ (0.4+0.6TITq SDI=1.148 - -- TD5T5Tg.Sa=So, T$<T5TL:S,,=S,i/T 1 o T>TL:S.=SQ,TL"V UU � U ' 1 I 0 1 1 1 a 1 1 I I I 1 ( a I 1 I I I , I 1 1 I I TO=0.108 TS=0.540 1.000 Period,T(sec) Section 11.4.6 — Maximum Considered Earthquake (MCE) Response Spectrum The MCE Response Spectrum is determined by multiplying the design response spectrum by 1.5. SH, 1.722 - � I t � 1 1 � I I 1 1 C 1 I 4 t 1 1 I 1 t � 1 1 � 1 1 � I 1 � 1 1 1 1 N SH1=0.929 - -;-----------r---------- C 1 1 1 0 1 1 h C I I I 6. I I I I I 1 1 I 1 f I I U I I a 1 I 1 a I 1 I W 1 I 1 1 I 1 1 1 1 1 1 t 1 1 ( I 1 Tq=0.108 T5=0.539 1.000 Period.T(sec) Section 11.6 — Seismic Design Category Table 11.6-1 Seismic Design Category Based on Short Period Response Acceleration Parameter VALUE OF S OCCUPANCY CATEGORY oS I or II III IV SoS < 0.167g A A A 0.167g 5 SoS < 0.33g B B C 0.33g 5 SoS < 0.50g C C D 0.50g <_ SpS D D D For Occupancy Category = I and SpS = 1.148 g, Seismic Design Category = D Table 11.6-2 Seismic Design Category Based on 1-S Period Response Acceleration Parameter VALUE OF S OCCUPANCY CATEGORY DI I or II III IV Spl < 0.067g A A A 0.067g <_ SDI < 0.133g B B C 0.133g <_ Spl < 0.20g C C D 0.20g 5 Spl D D D For Occupancy Category = I and SDI = 0.620 g, Seismic Design Category = D Note: When Sl is greater than or equal to 0.75g, the Seismic Design Category is E for buildings in Occupancy Categories I, II, and III, and F for those in Occupancy Category IV, irrespective of the above. Seismic Design Category "the more severe design category in accordance with Table 11.6-1 or 11.6-2" = D Note: See Section 11.6 for alternative approaches to calculating Seismic Design Category. References 1. Figure 22-1: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/ASCE7-2005-Figure22-01.pdf 2. Figure 22-2: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/ASCE7-2005-Figure22-02.pdf 3. Figure 22-15: http://earthquake.usgs.gov/hazards/designmaps/downloads/pdfs/ASCE7-2005-Figure22-15.pdf