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HomeMy WebLinkAboutCUP 02-23; LARWIN PARK; GEOTECHNICAL INVESTIGATION; 1991-05-09GEOTECHNICAL INVESTIGATION PROPOSED LARWIN PARK DEVELOPMENT CARLSBAD, CALIFORNIA Prepared for VAN. DYKE & ASSOCIATES Project No. 1317-SIO1 May 9, 1991 RECEIVED CITY OF CARLSBAD PLANNING DEPT. 4. GROUP DELTA CONSULTANTS, INC. GROUP DELTA CONSULTANTS, INC. Walter F. Crampton Engineers and Geologists Barry A. Bevier 4455 Murphy Canyon Road, Suite 100 Phillip C. Birkhahn San Diego, CA 92123 Braven R. Smillie Tel (619) 573-1777 Fax (619)-573-0069 Project No. 1317-5101. May 9,',1991 Ms. Liii O'Connor VAN DYKE & ASSOCIATES 2741 Fourth Avenue San Diego, California 92103 GEOTECHNICAL INVESTIGATION PROPOSED LARWIN PARK DEVELOPMENT CARLSBAD, CALIFORNIA Dear Ms. O'Connor: accompanying report of our geotechnical investigation for the subject project. The investigation was performed in accordance with our contract dated March 28, 1991. This report presents the results of our investigative work, as well as our conclusions and recommendations pertaining to the geotechnical aspects of the site. We have appended the, text from our first phase report on geologic hazards on the site, dated February 20, 1991. Logs of the test borings and trenches, along with mapped geologic information originally presented in the appended report, have been included in this report. We trust this information meets your needs. If you have any questions or if we can be of further service, please give us a call. GROUP DELTA CONSULTANTS, IN. Very truly yours, yjj Braven R. Smillie R.G. 402, C.E.G. 207 BRS/WFC/jc Attachments (14) Addressee Wal mpto: R.C.E. 23792, R.G.E. 245 is VAN DYKE & ASSOCIATES May 9, 1991 Project No. 1317-SI01 TABLE OF CONTENTS SECTION PAGE NO. 1 PROJECT DESCRIPTION 1 2 FIELD INVESTIGATION AND LABORATORY TESTING . . . . . . 2 3 SITE CONDITIONS, GEOLOGIC AND GEOTECHNIAL 'CONSIDERATIONS . . .. . . . . . . . . . . . . . . . . . 3 4 DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS ......3 4.1 General . . . . . . . . ............. 3 4.2 Excavation Characteristics of Soils in Proposed Cut Areas . . . . . . . . •. . . . ....... 4 4.3 Earthwork Recommendations .. . . . . . . . . . . .• 4 4.3.1 Specifications and Testing . . . . . . 4 4.3.2 Preparation of Areas to Receive Engineered Fills . . . . . . . ........• • 4 4.3.4 Expansive Soils. . . . . . . . . . . , 8 4.3.5 Stability of Fill Slopes and Cut/Fill Slopes • • • • • .............8 4.3.6 Stability of Cut Slopes . . . . .. . . 9 4.3.7 Temporary Construction Slopes . . . 10 4.3.8 Surface Drainage . . . . . . .• . . • 11 4.4 Foundations.., 11 4.4.1 Footing -Design. . . . ...... . 11 4.4.2 Lateral Resistance . . . . . . . . 12 4.4.3 SlabS-On-Grade 13 4.5 'Settlements ........ .... • .o o 13 4.6 Tennis and Basketball Courts . . . . . . . 14 4.7 Pavements and Walkways . ..o ... ...... 15 5 LIMITATIONS . . . . • . . . . . . . . • . . • . . . . 16 REFERENCES FIGURE 1 - SITE PLAN AND GEOLOGIC MAP APPENDIX A - SUMMARY OF GEOTECHNICAL CONSIDERATIONS REPORT DATED FEBRUARY 20, 1991 APPENDIX B - LOGS OF EXCAVATIONS APPENDIX C - SPECIFICATIONS FOR ENGINEERED FILL APPENDIX D — PORTLAND CEMENT ASSOCIATION (PCA) INFORMATION SHEET IS199T, "REINFORCED CONCRETE TENNIS COURTS" GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES Project No. 1317-SIO1 may 9, 1991 Page 1 GEOTECHNICAL INVESTIGATION PROPOSED LARWIN PARK DEVELOPMENT CARLSBAD, CALIFORNIA 1 PROJECT DESCRIPTION The Larwin Park site is an irregularly-shaped, undeveloped, hillside parcel, approximately 30 acres in area, on the north, side of Elm 'Avenue, and 1/2 mile east of El Camino Real in the City of Carlsbad, California. . . Plans at the 30 percent submittal stage inclu e 135,-00*0 bic yards of grading to prepare the site for softbal multi-purpose athletic fields, tennis and basketball courts, restroom and shade - k' ZL W.LJ way/maintenance vehicle access paths designed to connect the major activity areas. Reinforced concrete block walls, approximately 4 . feet in height, are planned in the basketball court and play lot areas, and an approximately 300-foot-long, 30- to 40-foot-high concrete cribwall (or an alternative gravity-type wall) is planned along a portion of the northwesterly property boundary in order to. maximize the usable area on this steep hillside site. Because of geologic and economic constraints, the final location of the cribwall has not yet been chosen. The proposed location of the cribwall is therefore not shown on the Site Plan and Geologic Map (Figure 1). Ancillary park improvements will include subsurface drains, storm drains and associated structures, and irrigation a equipment. Figure 1, the Site Plan and Geologic Map, shows the approximate locations of.these improvements, as obtained from the Option No. 6 Plan prepared by Van Dyke & Associates. In reviewing. Sheet 4 of the 30 Percent Submittal Larwin Park Grading Plan prepared 'by P & D Technologies, proposed grading associated with the development of play fields, located just easterly of the SDG&E power line easement, shows proposed fills encroaching into the easterly margin of the easement and, in one location, over an existing 6-inch high-pressure fuel line which parallels the easterly side of the SDG&E easement. We have no as- built information on the depth or material properties of the hig4- 41 DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project No. 1317-SIO1 Page 2 pressure fuel line, and evaluation of the effect of the proposed fill slope was not within the scope of this study. It may be desirable, however, to contact the governing utility to determine any requirements that may be necessary to encroach upon this utility. 2 . FIELD INVESTIGATION AND LABORATORY. TESTING a Group Delta Consultants, Inc., performed a geologic hazards study, reported February 20,. 1991. Two large-diameter bucket auger test borings and seven backhoe test trenches were excavated for this first phase study. Following a review of our first phase geologic hazards report of February 20, 1991, as well as available geologic and geotechnical literature, and historic stereopair aerial photographs of the site and surrounding •area,, a geologist from our firm made a site reconnaissance in order to evaluate the characteristics of surface soils. 44 An additional four soil test borings and five backhoe test trenches were excavated to complement geologic and geotechnical data 4 obtained from test borings and trenches for the investigation reported February 20, 1991. The test boiings for this second phase of the investigation were drilled with a tripod-mounted, hydrauli- cally-operated, Beaver portable power auger with a 4-inch-diameter, continuous-flight auger. The test trenches were excavated using a track-mounted Kubota KH-90 backhoe with a 24-inch-wide bucket. Drive samples were collected from the borings, and bulk disturbed 3 samples were collected from both the borings and the trenches. The samples were delivered to the laboratory for further examination and testing. All excavations were advanced under the direction of, and logged by, a geologist from our firm. A Key to Excavation Logs is presented in Appendix B as Figure B-i. Final logs of the excavations, combined with those from our earlier investigation, are presented as Figures B-2 through B-201 The approximate GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9,1991 Project No. 1317-SIO1 Page 3 locations of the test excavations from both investigations are shown on the Site Plan and Geologic Map, Figure 1. During our field geotechnical investigation, we were required to avoid making test- excavations or driving vehicles within certain biological resource areas, principally the proposed basketball and tennis court areas, and the southwesterly-facing slopes below the proposed athletic fields. Relatively conservative grading specifications, pavement section designs, and structural require- ments are provided in this report for those biological resource areas, with the understanding that, after the proposed grading is completed and the finished-grade soils are exposed, near-surface soil samples can be obtained and tested, and more precise (and likely more economic) design recommendations can be made. 3- SITE CONDITIONS, GEOLOGIC AND GEOTECHNJCAL CONSIDERATIONS The appended report, -"Summary of Geotechnical Considerations, Proposed Larwin Park Development, Carlsbad, California,, Of dated February 20, 1991, describes site conditions, geologic hazards and geotechnical considerations, and makes conclusions and recommenda- tions to mitigate geologic and geotechnical, constraints that may impact the project. The discussion, conclusions, and recommenda- tions in the following section are derived from data obtained from that - appended report, as well as from the current geotechnical investigation. A site-specific foundation study and evaluation of geotechnical design parameters for the proposed cribwall are not a part of this study. - 4 DISCUSSION, CONCLUSIONS AND RECOMMENDATIONS 4.1 General Based on the results of our field investigation, laboratory testing, and geotechnical evaluation, it is our opinion that the subject site is suited for the proposed development from a geotechnical engineering and engineering geologic point of view, GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project NO. 1317S101 Page 4 provided the recommendations presented in this report are imple- mented. The City of Carlsbad should be well aware of the geotech- nical impact of the surf icial landslides and creep soils, and, of the highly expansive clayey soils present over much of the site area. . All grading should be, conducted in accordance with the Grading Ordinance of the City of Carlsbad,' and the Specifications for Engineered Fill included in Appendix C of this report. 4.2 Excavation Characteristics of Soils in Proposed Cut Areas Based on our experience, and on the results of our exploratory work at the site, it is our opinion that the soils on site can generally be excavated -to design depths by medium to heavy effort with conventional heavy-duty grading equipment. The Santiago Formation, which underlies, the entire site within the depths of proposed graaing, contains zones or partially lime-cemented sands. These zones may require heavy ripping effort, and may. result in the generation of some oversize materials, requiring special placement as described in the Specifications for Engineered Fill, Appendix C. 4.3 Earthwork RecOmmendationS 4.3.1 Specifications and Testing All earthwork shall be performed in accordance with the Specifications for Engineered Fill provided in Appendix C. All grading operations should be observed, tested, and documented under the direction of a registered geotechnical engineer or certified engineering geologist, and in accordance with the Grading Ordinance of the City of Carlsbad. 4.3.2 Preparation of Areas to Receive Engineered Fills Vegetation - We recommend that all vegetation and other organic materials be removed from areas to receive fill Topsoils/Residual Soils Except where it has been removed by grading, the hillsides are covered with a relatively thin (generally I- to 2-feet thick) clayey topsoil, in turn I . GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project No. 1317-SIO1 Page 5 underlain by a residual layer of highly expansive1 -silty to fine sandy clay, derived from the underlying formational soils. The surf icial topsoil layer consists of porous, collapsible, clayey silt to silty clay,, and is considered unsuitable in its present condition for the direct support of any engineered fills and/or structures. We recommend that all loose and/or .porous topsoils within the limits of proposed grading be removed, and/or scarified' as required, watered, and compacted prior to placing any addi- tional fill. Recommendations for treatment' of expansive residual soils are made below in Subsection 4.3.4. Fill and Alluvial/Colluvial Soils - Our field investigation indicates relatively compressible fill and alluvi.al/colluvial soils in a relatively flat area, generally below elevation 160 feet, in the area of Boring No. B-6, where a maximum depth of approximately 20 feet of potentially compressible soils likely exist, These materials are also considered to be unsuitable in their present condition for support of any engineered ,f ills and/or structures. We recommend that soft, compressible soils in this area be removed, reprocessedE and/or replaced with properly compacted fill materials. The exact depth and areal extent of unsuit- able materials requiring removal and-recompaction-should be determined in the field by the geotechnical engineer, engi- neering geologist, or their representative, at the time of grading when the soils are exposed. Recommendations regarding the stability of construction cuts, especially in weak soils such as described above, are made below in Subsection 43.6. A relatively extensive amount of fill also exists within a partially filled canyon along the northwest boundary, just northerly of the proposed tennis courts. We have been unable to find-records documenting the quality or depth Of this fill, and are of the. opinion that, if this fill were originally placed without proper compaction and/or benching, this fill would also be unsuitable in its present condition for the GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9,. 1991 Project No. 1317-SIO1 Page 6 direct support Of the engineered fill supporting the northerly portion of the tennis court path Consideration should be given to additional record search to validate the quality of this fill to aid in evaluating it's suitability as a founda- tion soil for support of the proposed engineered fill. Landslide Areas - Figure 1 indicates the approximate lateral extent of landslide areas mapped by our firm on the site. As discussed on PageS 4 and 51 of the appended report, these landslides and soil creep areas are relatively, shallow, generally on the order of 5 to 10 feet in depth. It is our opinion that, if not removed, these relatively shallow "mobil zone" landslides and creep soils would likely not be subject to significant long-term consolidation under the load imposed by the proposed fills. However, because most of the slides have a significant out-of-slope component of movement with respect to the face of the proposed fill slopes, we recommend that, where not removed by normal bench-cutting of the slope, the slides be entirely removed by excavation within proposed fill areas. As is the case with soft and compressible soils, the exact depth and areal extent of landslide soils requiring removal and recompaction should be determined in the field by the geotechnical engineer, the engineering geologist, Or their representative, at the time of grading. when the soils are exposed. As noted in the appended report, shallow landslides and creep soils on Santiago Formation slopes often exhibit subtle (or no) surface expres- sion. It is therefore recommended that, during the grading process, bench cuts be observed by an engineering geologist, so that previously undetected landslides may be identified and removed. 4.3.3 Subdrains We recommend that subdrains be installed in the major drain- ages, as indicated on Figure 1. The subdrains should consist of 6.-inch perforated PVC or ABS pipe. For fill depths of 35 feet or less, we recommend 6-inch SDR-35 perforated pipe. For GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES Project NO. 1317-SI01 May 9, 1991 Page fill depths in excess of 35 feet, we recommend 6-inch SDR-21. pipe. Details of drain construction are provided in the. Specifications for Engineered Fill, Appendix C. All subdrains should be placed at a minimum 2 percent slope. It should be noted that1 often, the low point of the surface topography is not reflected in, the drainage clean-out, and that the actual location and length of the subdrain should be determined in the field. Notes are provided.on the Site Plan and Geologic Map, Figure 1, to indicate, recommended termina- tion points and connections for the subdrain outlets. a It should be observed that, because of the relatively abrupt changes in permeability between sandstone and claystone layers, the Santiago Formation exhibits a pronounced tendency toward the formation of multiple "perched" groundwater levels. During extended periods of abundant rainfall, or in the event of excessive irrigation, groundwater seepages (often resulting in surficial sloughage) can be expected to occur in cut slopes And/or at stratigraphic boundarieS between materials of differing permeability. A small example of this phenomenon can be observed in the cut Slope facing the residential parking garages in the area of the proposed Oribwall (near Slope Log No. SL-1). It should be expected that occurrences such as this, over •the next several years, will require mitigation in Order to prevent . deteriorating slope, surfaces and excessive "nuisance" erosion. . The most effective means to mitigate seepages of this type is likely to be the installa- on of small subdraiñs. The design of these subdrains will, of course, depend entirely upon the geometry of the strati- graphic seepage. As subsurface stratigraphic detail, future rainfall patterns,, and landscape irrigation are currently unknown or undefined, it is not feasible to determine poten- tial seepage areas or plan acoinpiete subdrain system. These subdrains can, and should, be designed and installed as needed over the life of the project1 when.cAndif seepages occur. GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project No. 1317-SI01 . . Page 8 4.3.4 Expansive Soils In our opinion, all soil materials generated on site during the grading operations are suitable for use as fill soils. Hôwever, the.•.clayèy topsoils, and the claystones and clayey siltstone portions of the Santiago Formation, may be expected to be moderately to highly expansive, and thus may not be suitable for use at finish grade.. The remainder of the on- site soils, predominantly silty to clayey sands from the Santiago Formation, range from nonexpansive to moderately expansive, respectively. As indicated by our test excavations, portions of the site are underlain by siltstones and claystones, with a moderate to high expansion potential. The undesirable effects of these expansive materials can be minimized by selective grading. If used as fill, these materials should not be. placed within 1 foot of pavements, or within 3 feet of the bottoms of footings. If exposed in cut, areas, the expansive materials should be overexcavated. to the same depths (1 foot. below pavements and 3 feet below footings), and the overexcavated area brought to finish grade elevations with nonexpansive or lOw, expansive granular material. We estimate that on the order of 25 to 35 percent of the on-site soils above elevation 200 feet could be classified, as nonexpansive, or low to moderately expansive granular materials. We recommend that the site be graded selectively so that these less expansive soils may be used in the upper 3 feet in areas where struc- tures are planned. 4.3.5 Stability of Fill Slopes and Cut/Fill Slopes Preliminary plans provided to us indicate that fill and cut/fill, slopes are proposed, which may extend up to approxi- mately 60 feet in height. We recommend that all fill and cut/fill slopes be constructed at slope ratios of 2:1 (hori- zontal to vertical) Or flatter. Slopes constructed of on-site. soils and/or imported granular soils are considered stable against deep-seated failures when constructed at slope GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project No. 1317-SI01 Page 9 inclinations no steeper than the recommended. 2:1. In addi- tion, we recommend that all fill slopes, or fill portions of cut/fill slopes., be keyed into existing formational, materials and benôhed in accordance with the grading specifications provided in Appendix c?. The importance of proper compaction of all fill materials out to the slope face cannot be overemphasized. Slopes should be either overfilled and cut back to a compacted finish surface, or the outer surface of the fill slopes should be backrôlled utilizing a sheepsfoot roller (at intervals not exceeding 4 feet in vertical height during placement), or grid rolled with standard grid rolling equipment. Permanent slope ma ants should be initiated immediately after the completion of slope construction in order to minimize future surficial sloughing. Slope, mainte- nance should include proper care of erosion, and drainage control devices, rodent control, and immediate planting with deep-rooted, . light-weight, drought-resistant vegetation. Experience has shown that slope performance. is largely dependent upon proper slope maintenance (planting, maintaining a uniform moisture content, clearing of drainage devices, etc.). Slopes which are properly planted and conscientiously maintained are not expected to exhibit significant ravelling or sloughing. 4.3.6 Stability of Cut Slopes We recommend that all cut slopes be constructed at slope ratios of 2:1 (horizontal to vertical) Or flatter1. On-site cut, slopes can generally be expected to expose competent formational materials, and: are considered resistant to deep- seated or surf icial slope instability. However, .as with fill slopes,' surficial ravelling and sloughing can still occur, especially when slopes are not adequately maintained and cared for. GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES Project No. 1317-SIO1 May 9, 1991 Page 10 We recommend that all cut slopes be inspected by an engineer- ing geologist during grading so that, should evidence of unstable conditions be observed, mitigating measures can be taken immediately. 4.3.7 Temporary Construction Slopes In areas, where existing slopes will require backcuts .f or the construction of retaining structures, or removal of old' fill or alluvium, we recommend that all construction slopes have a maximum inclination of 1:1 (horizontal to vertical), or flatter. In thiè regard, it appears that the most critical temporary construction slope on site will be along the property line in the area of Test Boring No. B-6, where excavation for removal of compressible soils and for the proposed cribwall (if it is built in this location) will result in a temporary cut slope op the order of 20 feet in height. In our opinion, such a slope will be grossly stable (although minor ravelling may occur from a sandy zone near the mid-point of the slope) for temporary construction. We have assumed that the term of the temporary construction slope would not exceed three (3) months, and would not extend into the rainy season.. Current OSHA regulations on excavation require that, for a temporary cut slope exceeding 20 feet in height, the slope must be shored according to shoring plans designed by a licensed civil engineer, and'approved by OSHA. Because the construction slope in' this area would likely be on the order of 20 feet or less, shoring will likely not be necessary; however, we recommend that excavation of the construction slope be continually observed by an engineering geologist in order to assess stability. Once construction has begun with the construction slope, work should progress at a reasonable rate so that the time that the slope is exposed to the elements is minimized. Backfill placed in front of the construction slope will require that the backcut (construction slope) be benched And keyed in accordance with the grading specifications provided in Appendix C. GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project No.. 1317-SIO1 Page 11 4.3.8 Surface Drainage We recommend that measures be taken to properly finish grade the site after structures and other improvements are completed so that positive drainage away from the structures exists Even when proper drainage measures have been taken, experience has shown that a shall groundwater or surface water condition may develop in areas where no such water condition existed prior to site development. This is particularly true when substantial increase in surface water infiltration results from landscape irrigation. We recommend that surface drainage be designed to have a minimum 2 percent slope away from buildings, and that all drainage waters are collected and directed to discharge structures via properly designed surface swales, ditches, or subsurface conduits. 4.4 Foundations and Slabs Two requirements must be fulfilled by any foundation soil' material. First, it should be safe against shear failure of the foundation soils which, would result in lateral movement of soil under the load. Second, foundation settlement or heave should be within acceptable limits for the structure. We understand that the proposed restroom structure(s) and the proposed shade structure will likely be constructed of reinforced concrete block. It is our opinion that such structures can be supported on conventional, isolated, or continuous footings. 4.4.1 Footing Design We recommend that the footing for the light- to medium-weight a restroom structure(s) and the proposed . shade structure be founded in properly compacted nonexpansive (El less than 50) fill soils or formational materials. We recommend an allow- able soil bearing pressure of 1,500 psf (dead load plus live load) for foundations placed in properly compacted fill soils and formational materials. Bearing pressures may be increased by one-third for loads that include wind or seismic forces. All footings should have a minimum width of 12 inches, be GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES Project NO. 1317-SIO1. May §,, 1991 Page 12 founded a minimum of 12 inches below lowest adjacent rough grade, and be reinforced with at least one No. 4 rebar, top. and bottom (2 bars total). In cases where footings would extend into forinational materi- als that would have a potentially expansive stratum underlying the proposed footing, We recommend that this stratum be overexcavated entirely, or a minimum of 3 feet below the bottoms of footings (whichever is less), and recompacted with , nonexpansive materials, in accordance with the grading specifications provided in Appendix C. The intent is to insure that the footing is not supported on: potentially . expansive material. In lieu, of recompaction, footings may be poured the full depth of the overexcavation. We recommend that all footings be set back a minimum horizon- tal distance of 10 feet from the top of any slopes. 4.4.2 Lateral Resistance To provide lateral, resistance for design lateral loads of footings and shear keys poured neat against vertical excava- tionS, we recommend using an equivalent fluid pressure of 300 pounds per cubic foot for properly compacted granular fill. This value assumes a horizontal surface for the soil mass extending at, least 10 feet from, the face of the footing,. or three times the height of the surface generating the passive pressure, whichever is greater. The upper 12 inches of soil in areas not protected by floor slabS or pavements should not be included in design for passive resistance to. lateral loads. If friction is to be used to resist lateral loads, we recom- mend a. coefficient of. friction of 0.35 between soil. and concrete. If it is desired to combine friction and passive resistance in design, we recommend using a friction coeff i- cient of; 0.25. GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES Project NO. 1317-SIO1 may 9, 1991 Page 13 4.4.3 Slabs-On-Grade. We understand that concrete slab-on-grade floors are planned for the restroom structure(s) and proposed shade structure. For slabs placed on soils of very low or low expansion potential (El less than 56), concrete slabs cast-on-grade Should have a 4-inch nominal slab thickness, and should be reinforced with 6 x. 6, 6/6 welded-wire mesh. The mesh should be placed at the mid-point of the slab, and care should .be. taken to maintain the mesh at mid-point by use of "chairs" or similar methods during the placement of concrete. 4.5 Settlements Settlements due to bui loads and construction procedures are expected to be on the order of 1/4 to 1/2 inch, or less. Differen- tial settlements are usually on the order of one-half this value. Compacted fills typically increase in moisture and settle Sometime during their lifetime. This occurs even when subsurface and surface drains are provided. These settlements may be on the order of 0.2 to 0,6 percent of the depth of the, fill. The lower range is often typical of more granular (Sandy) soils, and the upper value is more typical of cohesive (clayey) soils. Uniform settlements and linearly increasing Settlements often have no adverse affect on structures, and may not even be noticeable. However, when fill thicknesses change rapidly, as is the case beneath the proposed tennis and basketball courts, the additional fill settlements may result in cracking of •the concrete slabs at,. and near, the transitional area where fill depths change rapidly.. Poor drainage resulting in localized soil saturation may result in differential settlements across a structure equal to total combined initial plus long-term settlements. Potential differential settlements can be grossly estimated by comparing differential fill thicknesses below structures, or from the slope of the contact between fill, and the relatively incom- pressible. underlyIng formational material. GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES May 9, 1991 Project NO. 1317-5101 Page 14 As previously indicated, concern has been expressed about the suitability of the existing canyon fill northerly of the proposed tennis courts that will ultimately provide support for the proposed fill slope necessary to develop the tennis court pad in this area. Although we have no records to substantiate the quality 'of this fill, if left in place, the fill could contribute to additional differential, settlements to the tennis court pad, if it was not originally constructed as a properly designed engineered fill. Localized soil saturation is potentially damaging to structures founded in properly compacted fill soils, and should be. avoided. All graded pad surfaces, should be sloped to readily drain away from slopes, and into controlled surface drainage, facilities. The integrity of the drainage should be maintained to prevent soil saturation and its detrimental affects. . . 4.6 Tennis and Basketball Courts It should be expected, because. of the relatively steep natural slopes beneath the tennis and basketball courts,' at least. some differential settlement across the court surfaces can be expected. We recommend that tennis and basketball courts utilize 5-inch-thick reinforced-concrete slabs in strict compliance with the Portland Cement Association (PCA) information sheet. IS199T entitled "Reinforced Concrete Tennis Courts." A copy has been included. as Appendix D. After subgrade soils are exposed, we recommend that the entire subgrade be proof-rolled to test for any soft spots with a minimum 4,000-pound wheel load. Any observed soft spots should, be over- excavated 'a minimum depth of 18 inches, moisturized as necessary, and compacted to a minimum of 90 percent of the laboratory maximum, as determined by ASTM Test Designation D 1557-78. This is approximately equivalent to 95 percent of ASTM Test Designation D 698 (Page 10, Specification 2.c of the attached PCA Standard). No additional density testing shall be required. GROUP DELTA CONSULTANTS, INC. a VAN DIKE & ASSOCIATES . May 9, 1991 Project No.. 1317-SIO1 . . Page 15 2' We recommend that, after the project area has been graded, the . subsoils be kept moist, by watering, until the base material, and concrete are placed. . 4.7 Pavements and Walkways We have performed . analyses to evaluate pavement design i . procedures outlined by . the State of California, Departmenl Transportation (ALTRANS), and the Asphalt Institute. ' preliminary design p, we have assumed, a Traffic Index of 8.0 for the design of flexible pavements for on-site street ' parking areas. This.assumes periodic use by relatively heavy cian Diego Gas & Electric power line maintenance vehicles and by trash trucks. Based upon material characteristics and R-value tests performed on two samples, we have used a design R-value of 20 in our design. We recommend . that, once the. sub grade has been prepared, pavement design be confirmed by performing additional R-value testing prior to placement of pavement. Based upon our design assumptions, we recommend a design section of 3½ inches of asphalt concrete overlying 9 inches of Class II aggregate base. We recommend that the upper 12. inches of subgrade be compacted to 95 percent of the maximum density, as determined by ASTM Test Method D 1557-78. We recommend that Class II aggregate base be compacted to 95 percent of the maximum density, as determined by the, above ASTM standard. Asphalt concrete should .be provided and placed in accordance with Section 39 of the . "Standard Specifications," of the State of California, Department of Transportation (CALTRANS).' We recommend that mix designs for asphalt concrete be prepared by an engineering company 'specializing in this type of work, and that the paving operatIons, be inspected by a qualified testing laboratory. a We recommend that Surface drainage be provided, to prevent ponding water, and to reduce infiltration into the .subgrade materials. We recommend that paved areas have a minimum gradient of 1 percent. It should be noted that pavements designed using CALTRANS proce- dures have a design life of approximately 20 years under norma]. I GROUP DELTA CONSULTANTS, INC VAN DYKE & ASSOCIATES May 9, 1991 Project No. 1317-SIO1 Page 16. design conditions. The• recommended design does not take into. consideration frequent loading by heavy truck or equipment traffic. If heavily-loaded trucks or equipment are allowed to traffic the pavements during or after construction, localized areas of distress and/or a shorter pavement life must be anticipated. The pavement design also assumes that normal maintenance, such as periodic seal coating, should be performed to reduce infiltration of water and to maintain asphalt pavement surfaces. For walkway/maintenance vehicle acceSS paths, we are of the opinion that either Portland Cement Concrete (PCC) or asphalt concrete (AC) surfaces may be used. We would suggest that PCC, if used as the pavement section, be 5-inches thick,. unreinforced, and provided with control joints at a spacing equal to the path width. Asphalt concrete, if used, should be 4-inches thick if placed directly on compacted subgrade soils. An acceptable alternate AC section would be 2 inches of AC on .4 inches of Class II aggregate base. 5 LIMITATIONS We have observed only a small portion of the pertinent soil and subsurface conditions at the proposed project site. The recommen- dations made herein are based on the assumption that soil con- ditions do not deviate appreciably from those found during our field investigation. If the plans for site development are changed, or if variations or undesirable geotechnical conditions are encountered during construction, the Geotechnical Engineer should be consulted for further recommendations. It should be understood that California, including the City of Carlsbad, is an area of high seismic risk. It is generally considered economically unfeasible to build totally earthquake- resistant structures; therefore, it is possible that a large or, nearby earthquake could cause damage at the site. Professional judgements presented herein are based partly on our evaluation of the technical information gathered, partly on our understandirg of the proposed construction, and partly on, Our GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES. May 9, 1991 Project No. 1317-5101 . . . Page 11 general experience in the geotechnical field. Our engineering work and judgements rendered meet current professional standards. We do not guarantee the performance of the pro)ect in any. respect. This firm does not practice or consult, in the field of safety engineering. We do not direct the contractor's operations, and we cannot be responslble for the safety: of other than our own personnel on the site; therefore, the. safety of others is the responsibility of. the contractor. The contractor should notify the owner if he considers any of the recommended actions presented herein to be unsafe. GROUP DELTA CONSULTANTS, INC I a ' . VAN DYKE & ASSOCIATES Project No. 1317-9I01. May 9, 1991 REFERENCES 1i Occupational Safety and Health Adinistra.tion (OSHA) October 31, 1989., Part II, Department of Labor, 29 CFR Part 1926, Occupational. Safety and Health Standards - Excavations; Final Rule Schumm, Stanley A., and Mosley, M.P., eds., 1973, Slope Morphology,. Benchmark Papers in Geology: Dowden, Hutchinson and ROSS, Inc., Stroudsberg, PA. Schuster, Robert L., and Krizek, R. J., eds., 1978, Landslides Analysis . and Control, Transportation Research Board mmrñ rv1 4-r4m4a-1 C,4-mc 4r1 - -- Council, Special Report 176, National Academy. of Sciences. United. States Department. of Agriculture, 1953, Stereographic Black and. White Vertical Aerial Photographs, Scale 3 incheS approximately eq -ale 1 mile., Photo Nos. X1-8M-102 through 104. Weber, F. Harold, 1963, Mines and Mineral Resources of San Diego County, County Report 3, California Division of Mines and Geology. Weber, F. Harold, 1982, Recent Slope Failures, Ancient Landslides., and Related Geology of the North-Central Coastal Area, San Diego County, California, California Division of Mines and Geology, Open-File Report 82-12LA, 77 pages, 1 map sheet, scale 124,00O - GROUP DELTA CONSULTANTS, INC. k. MUir: Curing. The concrete immediately after finishing shall be kept continuously moist by covering with polyethylene film or waterproof cunng paper, or by spnnkhng or ponding for a geriod of at least 5 days if the temperature is above 70 F or for at least 7 days in cooler weather A cunng compound may be used pro vided that it is the type that will not interfere with adhesOn of the paint Used for the playing lines or any color coating on the surface. 6. Surface Coloring Applicdt4ft Coloring of surface areas shall be as indi- cated on the drawings The application of color shall be performed by skilled mechanics in a workmanlike manner in accordance with the manufacturer's stand- ard printed instructionS1 Coloring Method, Surface coloring shall be achieved by the use of [insert one of the following methods] I One-Course Integral Concrete Coloring Unilorm ly mix into the concrete a natural Or synthetic iron oxide color pigment that does not exceed 10% of the portland cement by weight, the dry cement and color pigment shall be. thoroughly blended before Water IS added to the mix.. 2 Monolithic Colored Concrete Topping The sur, face of the base slab.shall be struck off and bullfloated so that the surface is reasonably true and at a level not quired final grade. Beforc the colored topping coUrSe is placed, any bleed water shall be allowed to evapo rate from the surface of the base slab At the time the topping is placed, the concrete in the base slab shall be hard enough so that footprints of the workmen are barely perceptible The previous paragraph on integral coloring also applies. 3. Dry-Shake Method. The dry-shake method con- sists of applying a factoryprepared dry color material over the concrete surface after preliminary floating, edging, and grooving, Two applications of the dry shake shall be made, the first Using aboUt two-thirds of the total amount specified by the manufacturer. The surface shall be floated after each application to make sure the color is uniformly worked into the concrete 4 Colored Coatings and Stains Surfaces shall be thoroughly delnCd of foreign mattel. The color finish material shall be [insert name of preferred material] as manufactured by [insert name and address of manu- facturer] and shall be guaranteed for one year from date of finihed application against checldng, fading, chalking, discoloration, or other adverse effects of weather. The materini shall be delivered to the site in its original unopened containers clearly labeled with trade name and name of manufacturer and shall be applied according to the recommendations of the man- ufacturer. Z Playing Lines Base lines shall be painted not more than 4 in. wide, cen- ter lines shall be 2 in wide, and other service or playing lines not more than 2 in wide, accurately located in ac- cordance with the rules of the United States Tenms Asso- ciation. Use of traffic (oil and alkyd) paints is prohibited The painting shall b done by skilled mechanics in a workmanlike manner in accordance with the manufac- turer's standard printed instructions. This publication is intended for the use Of professional personnel competent to evaluate the significance and limitations of its con- tents and who will accept responsibility for the application of the material it contasne m The Portland Cement Association disclaims any and all respOnsibilty for application Of the stated principles or for the accuracy of the sources other than work performed or informa- tion developed by the Associatiofl CautiOfl; Avoid prolOflged contact between unhardened (wet) ce- ment. or concrete mixtures and skin irfaces. To prevent such con- tact it is advisable to wear protective clothing. Skin areas that have been exposed to wet cement or concrete, either directly or through saturated clothing, should be thoroughly washed with water. 3 • PORTLAND CEMENT I1I I ASSOCIATION I An oganiulion of cement manufactuem to impeses and eztefld the um of Portland cement and concrete thiough tcienli& reitaich, engineseing held nvrli. and IWIet deeelopment. 5420 Old Orchard Road, Skokie, Illinois 60076 Printed in U.S.A. 1S199.01T Was APPENDIX A SU}ARY OF GEOTEcIUICAL CONSIDERATIONS PROPOSED LARWIN PARK DEVELOPMENT ABLAD, CALIFORNIA DATED FEBRUARY 20 1991 I a GROUP DELTA CONSULTANTS, INC. APPENDIX A SUMMARY OF GEOTECHNICAL CONSIDERATIONS PROPOSED LARWIN. PARK DEVELOPMENT CARLSBAD, CALIFORNIA DATED FEBRUARY 20, 1991 S al GROUP DELTA CONSULTANT'S, INC. SUMMARY OF GEOTECHNICAL CONSIDERATIONS PROPOSED LARWIN PARK DEVELOPMENT CARLSBAD, CALIFORNIA Prepared for VAN DYKE & ASSOCIATES Project No. 1317-GE61 February 20, 1991 GROUP DELTA CONSULTANTS, INC. GROUP DELTA CONSULTANTS, INC. Walter F. Crampton Engineers and Geologists Barry A. Bevier 4455 Murphy Canyon Road, Suite 100 4 Phillip C Birkhahn San Diego, CA 92123 Braven A. Smillie Tel (619) 573-1777 Fax (619) 573-0069 Project No. 1317-GE01 February 20, 1991 Ms. Liii,. O'Connor VAN DYKE & ASSOCIATES 2741 Fourth Avenue San Diego, California 92103 a SUMMARY OF GEOTECHNICAL CONSIDERATIONS PROPOSED LARWIN PARK DEVELOPMENT CARLSBAD, CALIFORNIA Dear Ms. O'Connor: I In accordance with your request, we have made a firbt—?llcthe evaltiatioi' of geologic cdnditionsat the subject isite. The primary purpose of our investigation is to provide S a preliminary understanding of the geotechnical and geologic conditions at the site as they relate to the pre-design phase of the proposed park site facilities. Specific recommendations may be, presented following finalization of site design, in a subsequent geotechniôal investigation. 1 FIELD INVESTIGATION On Nàvémber 26 through 29, 1990, a geologist from our firm $ performed a preliminary geologic reconnaissance, and inspected and downhole logged two large-diameter test borings and seven.backhoe test trenches. The approximate locations of our borings and test Z trenches are shown on the accompanying geologic map. We intend to perform further subsurface exploration when the approximate location and layout of improvements for the proposed park are known. 1••• VAN DYKE & ASSOCIATES February 20, 1991 Project No. 1317-GE01 TABLE OF CONTENTS SECTION PAGE NO. 1 FIELD INVESTIGATION . . . . . . . .. . . . . . . . . 1 2 SITE CONDITIONS AND GEOLOGY . . . . . . . . . . . . . . 2 2.1 Site Description . . . .. s..•s. . . . . . ..... 2 2.2 Geologic Setting . . .. . . . . . . ........2 2.3 Subsurface Conditions . . . . S • • . . . . . 3 3 GEOTECHNICAL CONSIDERATIONS . . . . . . .. . . . . . . 3 3.1 Faulting and Seismicity. . . . . . . . . •. . . . . . 3 3 .2 Landslides . . . . . . . . . . . . . . . . . . .. . 4 3 .3 Site Drainage . .. ........ ........ 5 3.4 5 4 CONCLUSIONS AND RECOMMENDATIONS •. . . . . . . . . . . . 5 5 LIMITATIONS . . . . . . . . .. . . . . . . . . . . . . 7 REFERENCES FIGUR.1 - SITE PLAN AND GEOLOGIC MAP APPENDIX A - LOGS OF EXCAVATIONS GROUP DELTA CONSULTANTS, INC. 41- a VAN DYKE & ASSOCIATES Project No. 1317-GE01 February 20,, 1991 Page 2 2 SITE CONDITIONS AND GEOLOGY 2.1 Site Description The proposed Larwin Park is situated on the upper slopes of a northerly-draining tributary to the Buena Vista Lagoon drainage system, approximately 2 'Miles from the shoreline in Carlsbad, California. The irregularly-shaped site is bounded on the south by Elm Avenue, and on the east and west by residential developments. The site is comprised of relatively flat areas along the easterly and extreme southerly portions. From these flat areas, relatively steep hillsides slope down to the north and west to a northwesterly-trending drainage. Relief from upper slopes to the, canypn bottom is on the order of 100 feet. An approximately 150- northwest-southeast across the site, and contains electrical transmission towers and the Santa Fe fuel pipeline. We understand .that structures for the proposed park site will be located primarily on the 100-foot-high northerly' facing slope. below Elm Avenue. These structures include a combined restroom and\ storage facility, and a cribwall Or other gravity-type retaining structure. The proposed retaining structure is on the order of 350-feet long, and up to 35-feet high. A second restroom facility may be located on relatively flat ground at the eastern edge of thJ site. Specific investigation and evaluation of subsurface conditions underlying these structures will be required prior to construction. This work can be performed, during a subsequent phase of the project, following the final location of improvements 2.2 Geoloaic Settin The site is located near the eroded edge of a remnant Quaternary- aged wave-cut marine abrasion terrace, formed along the southern California coastline during a higher interglacial sea stand. The. site is underlain, by sands and clays, characteristic of the Tertiary-aged Santiago Formation. GROUP DELTA CONSULTANTS. INC. VAN DIKE & ASSOCIATES February 20, 1991. P]oject No, 1317-GE01 Page 3 2.3 Subsurface Conditions Minor amounts of artificial fills were encountered on site, as shown on the accompanying geologic map. These consist predominantly of small fill pads at the southern portion of the site adjacent Elm Street, and fill areas extending front the condominium complex at the southwesterly portion of the 'site. An additional fill area, is located in the northeastern portion.of the site. These existing fill soils are estimated to be on theordér of 10 to 15 feet in thickness. The flatter areas at the base of the slopes contain a varying thickness of loose alluvial/colluvial soils. These, are estimated as being in excess of 2 feet. in depth, and likely range up to 8to The hillsides are mantled with a relatively thin (generally 1- to 3-feet thick) layer of topsoil. These topsoils are predominantly sandy clays with low permeability. Very minor amounts of Quaternary-aged terrace deposits exist at the higher elevations at the northeast portion of the site. These minor remnants, left from grading of the adjacent site, are not included on the geologic map. The site is underlain at shallow depths by gray, olive, or brown 41 sands, 'clays, and sandy or silty clays typical of the Tertiary-aged Santiago Formation. These formational materials are similar to those found throughout the Carlsbad and Oceanside' areas. I - - 3 GEOTECHNICAL CONSIDERATIONS 3.1 Faulting and Seismicity No faults or evidence of faulting was observed on the site during our investigation. Our review of aerial photographs and other pertinent geologic literature did not reveal any faults mapped on or adjacent to the site. GROUP DELTA CONSULTANTS, INC. VAN DYKE & ASSOCIATES . February 20, 199.1 Project No. 1317-GEO1 . Page 4 a. Site seismicity will be, addressed in our final geotechnica]. report. Seismicity is not, however, anticipated to present a significant constraint to site development. 3.2 Landslides Although our investigation is not complete, explorations performed to date have not revealed the existence of any massive, or deep- seated landslides in the slopes below. Elm Avenue, and we do not anticipate that any deep-seated soil movement will be encountered. However, our field reconnaissance, aerial photo interpretation, and . inspection of test explorations have revealed the existence of numerous' surf icial landslides and creep soil zones in this area. Landslide areas revealed by our site reconnaissance, geologic --------- --• Geologic Nap, Given the clayey nature of the on-site soils, it is considered likely that the majority of the site is affected by Soil creep, and possibly by additional surf icial landslides which were not apparent at this level of investigation. I Our investigative work to date indicates that, although areally extensive, these landslides and creep areas are shallow, generally S 20 feet or less in depth, and probably averaging less than 10 feet in depth. Although shallow, these areas must be mitigated wherever , development is proposed. Landslide and creep zones in areas of proposed development will require additional subsurface investigation to more fully define their depth and extent. This additional investigation can be most effectively performed following preparation of final site design. a The soil movement observed on the site is likely due to, two factorS. The first type of movement is soil creep, where a near-.. saturated soil mass moves imperceptibly downhill. This downhill -movement is a product of existing site conditions, such as steep slopes, near-saturated (and therefore heavy) surf icial Soils, and low-strength. (usually clayey) subsurface materials. High moisture conditions also contribute to. movement by "lubricating" existing shear zones within the 'clayey soils. GROUP. DELTA CONSULTANTS, INC. P VAN DYKE & ASSOCIATES February 20,1991 Project No. 1317-GE01 Page. 5 The second type of movement is propagated along pre-existing Shear surf aces which generally appear parallel, to bedding..attitudes. These attitudes seem to change orientation significantly over relatively small distances, apparently due to local, changes in depositional conditions. S Given the known abundance of pre-existing shear surfaces throughout the site area, it can be expected that there, is a high potential ' for surf icial landsliding (see. Figure 1,, Site Plan and Geologic Map). Additional landslides may exist that were not evident during our field reconnaissance or investigation. 3.3 Site Drainage clayey and, characteristically, relatively impermeable. . Any hardscapS site improvements, such as asphalt roads and. parking areas, tennis and basketball courts, etc., will be impervious •to irrigation and rain water. As-site improvements will likely. require irrigation, it is anticipated that runoff from the site will increase significantly. Expansive Soils Expansion or swell testing of on-site materials was not within the scope of our investigation. However, our experience with similar clayey soils in the area indicates that these materials are likely to be highly expansive, and may adversely affect proposed improvements. 4 CONCLUSIONS AND RECOMMENDATIONS The following comments are, of necessity, relatively general in nature. More specific information will be presented following final site design and subsequent additional investigation. 1. Surf icial soils are not adequate for support of any proposed fill soils or site improvements in their existing condition. GROUP DELTA CONSULTANTS, INC. a VAN DYKE & ASSOCIATES February 20, 1991 Project NO. 1317-GE01 Page 6 These surficial materials, which include existing fill soils, topsoils and alluvial/colluvial soils, will likely require removal and recompaction. Alternatively, if necessary, • structures may be designed to accommodate anticipated soil movements. 2. Existing landslide and creep. zone areas should be mitigated : prior to placement of fill Soils and construction of site improvements. This is especially important, since additional ? water from site, irrigation will likely increase the potential to increase slide/creep activity. These zones can be treated *" by removal and recompaction of the mobile areas, construction of a fill buttress, or by design of relatively flexible improvements which can accommodate movement. 3. Due to the abundance of known landslides and the pervasive nature of shear subsurfaceS, subsurface soil conditions in foundation areas are extremely important. These conditions - are of particular concern for the .proposed structures; the . restrooms and the planned gravity-type retaining wall. It is our understanding that you intend to remove and recompact landslides known to exist within proposed building areas. S However, as noted in Section 3.2, above, landslides may exist in areas where they are not evident and are not mapped. It is therefore recommended that additional exploratory investigation, consisting of drill borings and/or backhoe trenches, be performed once the locations of these structures have been finalized. 4. In the event that adverse conditions are observed in footing. or fill-key excavations, mitigation recommendations will be made as needed. a 5. Due to the relatively impermeable nature of the on-site soils, the proposed construction of impervious Site improvements, and anticipated application of irrigation water, runoff from the site will likely increase significantly. Subdrains will likely be required adjacent existing downslope improvements in order to minimize unwanted' drainage to off-site property. GROUP DELTA CONSULTANTS, INC. I VAN DYEE &: ASSOCIATES Project No. 1317-GE01 February 20, 1991 Page 7 other required drainage structures and improvements can best be evaluated following finalized site design plans. 6, On-site soils are likely to be highly expansive.. Mitigation. of expansive soils may include selective grading to place nonexpansive soils in structural areas, or the use. of more robust foundation design for proposed improvements. 5 LIMITATIONS The conclusions provided in this preliminary report are based on 3 the assumption that the soil and rock conditions do not deviate appreciably from those observed by our observations and excavations The conclusions presented in this preliminary report were prepared in general accordance with accepted professional principles and practices in the fields of geotechnical engineering and engineering geology. This warranty is ifl, lieu of all other warranties, either express or implied. We appreciate the opportunity to work with you on this project, and trust this information meets your needs. If you have any questions or require additional information, please give us a call. for GROUP DELTA COSULTANTSI INC. Verytr ly 0 rS Welfo d E. arnftr R.G. 4339, 9.E/a, 1.505 WEG/BRS/jc Attachments GROUP DELTA CONSULTANTS, INC. Braven R. Smillie LG. 402, C.E.G • 207 4T VAN DYKE & ASSOCIATES February 20, 1991 Project NO. 1317-GE01 REFERENCES Schunun, Stanley A., and Mosley, M.P., eds., 1973, Slope Morphology , Benchmark Papers in Geology: Dowden, Hutchinson and Ross, Inc., Stroudsberg, PA. Schuster, Robert L., and.Krizek, R.J., eds., 1978, Landslides - Analysis and Control, Transportation Research Board Commission on Sociotechnical Systems, National Research Council, Special Report 176, National Academy of Sciences. United States Department of Agriculture, 1953, Stereographic Black and White Vertical Aerial Photographs, Scale 3 inches approximately equals 1 mile, Photo Nos. AXN-8M-102 Weber, F.. Harold, 1963, Mines and Mineral Resources of San Diego County,, County Report 3, California Division of Mines and Geology. Weber, F. Harold, 15920 Recent Slope Failures, Ancient Landslides, and Related Geology of, the North-Central Coastal Area,: San Diego County, California, California Division of Mines' and Geology, Open-File Report 82-12LA, 77 pages, 1 map sheet, scale 1:24,000. GROUP DELTA CONSULTANTS, INC. NOTE FIGURE 1 and APPENDIX A OF "SUMMARY OF GEOTECHNICAL CONSIDERATIONS PROPOSED LARWIN PARK DEVELOPMENT CARLSBAD, CALIFORNIA" dated FEBRUARY 20, 1991 HAVE BEEN INCORPORATED INTO. "GEOTECHNICAL INVESTIGATION PROPOSED LARWIN PARK DEVELOPMENT çARLBAD, CALIFORNIA" dated MAY 9, 1991 ii GROUP DELTA CONSULTANTS, INC. APPENDIX B LOGS OF EXCAVATIONS GROUP DELTA CONSULTANTS, INC. Ic E Y TO E X C A V A T I 0 N L 0 0 S LOGGED BY: DATE EXCAVATED: ELEVATION EXCAVATION NUMBER: EQUIPMENT: - - DIMENSIONS: RA!lER WI.: DROP: o DESCRIPTION L 090, - 14 Medium dense, moist, brown SILTY PINE SAND (SM) - - Unified SaLt ClassificatIon ' - t Water Table Measured On Date Indicated 5- - Number of Blows Reqnired to - AdvanOe Sampler One FOot Sample Type C Cgli'forniC Drive with Rings PB Plastic Bag SK Bulk Sack Sample S Standard Penetration Drive Sample Location Depth, Below Surface Elevation Indicates Samples Tested for Other Properties: NOTES ON FIELD INVESTIGATION Test Boring Nos. B-i and B-2 were advanced using a truck-mounted Earthdril]. 45L with a 30-in6h bucket. Test Boring Nos. B-3 through B76 Were advanced using a tripod-mounted, hydraulically-operated, Biaver portable power auger with a 4-inch-diameter, continuous-flight auger. Test trenches were excavated using a track-mounted Kubota X590..backhOe with a 24-inOh-wide bucket. The Slope Log, SL-1, was prepSred by a geologist from our firm, from his inspection of the exposed cut slope, without need of excavation equipment. ThC Standard Penetration Test (SPT) and California Sampler were used to obtain drive samples The SPT and California Samplers were driven into the soil at the bottom of the borings with a 140-pound hammer falling 30 inches. When the samplers were withdrawn from the boring, the samples were removed, visually classified, sealed in plastic containers, and taken to the laboratory for detailed inspection. The Standard Penetration Test (SPT) is. an 18-inch-long, 2-inch O.D., 1-3/8-inch I.D. drive sampler. The California Sampler Is an 18-inch-long, 2%-inch 1.0., 3-inch O.D., thick-Walled Sampler? The sampler is 1.6.lined with eighteeN 2-3/8-inch U. brass rings. Relatively undisturbed, intact soil samples are retained in the brass rings - Free groundwater Was encountered it Test Baring No. B-i, as shown on the log. ClassifiCatiOns are based upon the Unified Soil Classification System and include color, moisture and consistency. Field descriptions have been modified to reflect results of laboratory analyseS, where deemed apprOpriate. Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJXCT NO.: 1317S101 L A R W I N P A R IC FIGURE NO.: B - 1 GROUP DELTA CONSULTANTS, INC. Engineers and 'Geologists LOOM Bye GS - DATE DRILLED: 11-27-90 BORING ELEVATION: 213+ feet BORING NO.: DRILL RIG Earthdrill. 45L BORING DIAMETER: 30 inches HAMMER WI.: N/A DROP: N/A D B S C R I P T I 0 N :MEw , Loose, dark gray-brown-CLAYEY MEDIUM TO FINE SAND (SC) TOPSOIL Dense, dry, light gray SILTY SAND (SM) - - SANTIAdO FORMATION 5— - - Hard, damp, light olive-gray MEDIUM TO FINE SANDY CLAY (CL) 10 - - Hard, damp, olive-gray SILTY CLAY (CL) 15 - - - - Dense, damp to moist, gray SILTY SAND (SM) - Hua4,_duui,_y_SILTY_CLAY_ tun) _(highly _frnct.ured)20 - - - Hard, damp,.o].ive-gray SILTY CLAY (CL) remolded clay seam (N70W/2E) at 20 feet - (average 1.0-inch thick) 25— - - - Dense to very dense, damp, light tan SILTY TO CLAYEY MEDIUM TO FINE SAND (SM-SC) - remolded Clay seam (average 0.5" thick) at 25 feet - (bedding parallel) 30— - - Hard, damp, olive-tan SANDY CLAY (CL) 35 - becoming mottled brown/orange Dense, very moist, gray SILTY MEDIUM TO FINE SAND (SM) - - V Hard, wet, olive-gray SILTY CLAY (CL) (fractured) 40 - - with pieces of charcoal - (abundant seepage at 40 -fast from localized perched water) 45 - Joint p3.áe - N10E/45W 50 - LOG CONTINUED ON FIGURE A - 2 b Descriptions on this boring log apply Only at the specific boring location and at the time thi boring descriptions on this log are not warranted to be representative of subsurface conditions at other Locations was made. The or times. PROJECT NO.:1317-SIO1 LARWIN PARK. IFIGUREN0.: 32a GROLf DELTA QNULTANTS, INC. BORING LOG LOGGED BY: GS DATE DRILLED: 1127-SO BORING ELEVATION: 213± feet J BORING NO.: B - 1 DRILL RIG: Earthdrili 41% BORING DIAMETER: 30 inches HAMM WT. N/A DROP: N/A _J d DESCRIPTION FA CONTINUATION 07 FIGURE A - Za - SANTIAGO FORMATION - Hard, wet, olive-gray SILTY CLAY (CL) 55 - Dense to very dense, wet, gray SILTY MEDIUM TO FINE SAND (SM) - Dense to very dense, wet, olive-gray CLAYEY MEDIUM TO FINE SAND (SC) 60 - 65— - - Hard, wet, olive-gray FINE SANDY CLAY (CL) with discontinuous remolded clay seams • generally parallel. - to bedding (average 0.5-inch thick) 70 - - Dellis to very dense, wet., gray SILTY MEDIUM TO FINE SAND (SM) 75 - Hard, wet, olive-gray SILTY TO FINE SANDY CLAY (CL). - Dense to very dense, wet, gray SILTY SAND (SM) 80 - 85 - - - - - - BOTTOM OF BORING at 85 feet 90 - 95 - 100 - Descriptions on this boring log apply only at the specific boring location and at the time the boring was wade. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJFZT NO.: 13175101 L A R W I N P A R IC FIGURE NO.: B 2 b I GROUP DELTA cQNUANTS, INC. tngineers and ueo am NORIIG LOG LOGGED B!: GS DATE DRILLED: 11-27 -90 BORING ELEVATION: 222± feet BORING NO.: 3- 2 .DRfl.L RIG: EarthdriU. 45L BORING DIAMETER: 30 inches HAMMER WI.: N/A DROP: N/A DESCRIPTION H iq - Loose, dry, dark gray-brown SANDY CLAY (CL) TOPSOIL - Hard, damp tan SANDY CLAY (CL) - SANTIAGO FORMATION 5- 10— - Dense, damp, gray-brown SILTY SAND (SM - Hard, damp, tan FINE SANDY CLAY (CL) 15 - Dense, damp, tan SILTY MEDIUM TO FINE SAND (&l) - 20 - Dense, damp, mottled gray-brown SILTY SAND (UM) Dense,, damp, tan-gray SILTY SAND () = 25 -- Hard, damp, olive-tan FINE SANDY CLAY (CL) 3,0 - - BOTTOM OF BORING at 32 feet - No free groundwater encountered at time of excavation 35 - 40 - 45 - 50 Descriptions on this boring log apply only at the specific boring location and at the time the boring was made. The descriptions on this Log are not warranted to be representative of subsurface conditions at other locations or time. FROJT NO.: 1317-5101 . ' LARWIN P A R IC FIGURE NO.: B - 3 GROLf DELTA NU¼LT SANTSP INC. V 0 ( BORING LOG LOGGED BY MEG DATE DRILLED 040291 BORING ELEVATION 176 feet BORING NO B- 3. DRILL RIG: Beaver - Pacific BORING-DIAMETER: 4 inchei RAllIER WT: 140 lbs. DROP: 30 in. 43 DESCRIPTIO OR H - - - - - Very stiff, damp to moist, gray-brown SILTY TO FINE SAND( CLAY (CL) - - TOPSOIL 2 5 14 - - - Dense, damp, olive-gray to tan CLAYEY FINE SAND (SC) SANTIAGO FORMATION 5--- Very dense, damp, light olive-gray SILTY FINE SAND (SM/ML) - - 3 S 45 4 S - 50 - Very dense, damp, light olive-gray SILTY FINE SAND (SM) 10 - 50 5 S Very dense, damp, light olive-gray SILT! TO CLAYEY FINE SAND (SM/SC) - 'Vary dense, clamp, light olive-grey SILTY MEDIUM TO FINE SAND (SM) - 15 - 50 -I--__l - - 20— - - 50 - BOTTOM OF BORING at 21 feet - No free groundwater encountered at time of excavation 25 - 30 - 35 - 40 - 45 - 50 Descriptions on this boring log apply only at the specific boring location and at the time the boring was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJBOT NO.: . 1317-SIO1 L A R W I N P A R K J FIGURE NO.: B - 4 ROLLP DELTA cNU1jANTS, INC. BORING LOG LOGGED BY: NEC DATE DRILLED: 0401-91 BORINGELEVATION- 166 feet BORING NO.: B- 4 DRILL RIG Beaver - Pacific BORING DIAMETERi 4 inches IIAZ*DR NT 140 lbs DROP 30 in DESCRIPTION H 44 - - - 5— : - 10 - - - 21 50 .. 50 50 34 Moist to wet, olive-brown SANDY CLAY (CL/CE) FILL - - 1 C 50 SANTIAGO Very dense, damp, olive-gray SILTY FINE SAND (SM/MI.) FORMATION - - ..! .L. :i :S Very dense • damp, very light gray SILTY FINE SAND (SM) - Very dense, damp, olive-gray FINE SANDY SILT (ML), with trace of clay 4 S -: Fva- ydense, damp, olive-gray SILTY FINE SAND (SK/ML) - S - 15 BOTTOM OF BORING at 13½ feet No free groundwater encountered at time of excavation 20 - 25 - 30 - 35 - 40 - 45 - 50 Descriptions descriptions on this on this boring log apply only at the specific boring location and at the time the boring was mace. The log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO. : 1317S101 L A R W I N PARIC FIG= NO.: B-5 BORI!G LOG LOGGED By:.WEG DATE DRILLED 04-01-91 BORING EEXVATIONi 164 feet BORING NO B- 5 DRILL RIG Beaver - Pacific BORING DIAMETER 4 inches RAllIER WI 140 lbs DROP 30 in. * I I h DESCRIPTION - - 9 Stiff, wet, dark olive-gray SILTY CLAY (CH) TOPSOIL 1 - C Stiff, moist, mottled gray and tan SILTY CLAY (CH) SANTIAGO FORMATION - 21 Hard, damp, light brown CLAYEY TO FINE SANDY SILT (ML) - 10 - 42 - 3 - S - BOTTOM OF BORING at 113% feet - No free groundwater encountered at time of excavation 15 - 20 - 25 30 - 35 - 40 - 45 - 50 Descriptions dascripticneon on this this boring log apply only at the specific boring location ad at the time, the boring was made. The log are not warranted to be'representative of. subsurface conditions at other locations or times. PROJFCT NO.: 1317-SIO1 L A R W I N P A R K , FIGURE NO.: B 6 GROUP DELTA CONSULTANTS, INC. tnguneers and ueologists BORING LOG LOGGED BY: WE. DATE DRILLED. 04-01-91 BORING EL;WIPNi 164 feet BORING NO.: B - 6 DRILL RIG Beaver - Pacific BORING DIAMETER 4 Inches RNIIER NT 140 The DROP 30 In 14 DESCRIPTION - - 10 - - 15 - 13 9 8 Damp, light OlivebroWn CLAYEY PINE SAND (SC) FILL —i- - -i-- 2 - S 5357 Damp to moist, brown SILTY FINE SAND (SM) - 4 -. S Medium stiff, damp, dark Olive-brown SILTY CLAY (CE) LLUVIUM - 5 - S 20 - 25 - 30— - .6 - S 18 50 ' Stiff, damp, dark olive-brown SILTY TO FINE SANDY CLAY (CL/CE) •. - Hard, damp, olive gray-brown 'I*E SANDY CLAY (CL) . SANTIAGO FORMATION - - - - - 8 S - - 35- 40 - 45 - 50 . BOTT1 OF BORING at Si feet No free groundwater encountered at time of excavation Descriptions on this boring log apply only at. the specific boring locatiOn and at the time the boring escriptions g this Lo are not warranted to be representative of subsurface conditions at other locations was made. Th. or tinea. PROJSCT NO.; 1317-001 L A RW I. N P AR K 1 FIGURE NO.: B - 7 GROUP DELTA CQNULAFTs, INC nguneers and iieo ogis TRENCH LOG LOOM BY: GS DAlE EXCAVATED: 11-27-90 SURFACE ELEVATION: 195+ feet J TRENCH NO.: T- 1 EQUIPMENT: Kubota 91 Mini Trackhoe DIMENSIONS: 24" x 15' DESCRIPTION to - Median dense, dry, brown CLAYEY SAND (SC) TOPSOIL 1- Dense, dry, light gray SILTY SAND (SM) - 2 - SANTIAGO FORMATION 3- 4- Hard, damp, olive-gray FINE SANDY CLAY (CL). - 5— Dense to very dense, damp, light gray SILTY MEDIUM TO FINE SAND (SM) - 7 - BOTTOM OF TRENCH at 61 8" • No free groundwatir encountered at time Of excavation - NOTE: Log representative of vertical section at, approximate mid-point of trench 8- 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. .PROJECT NO.: 1317-2101 LARWIN PARK FIGURE NO.: B-8 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists IT TRENCH LOG LOGGED BY: GS DE CCAVATED 11-27-90 SURFACE ELEVATION: 166± feet TRENCH NO: T- 2 EQUIPMENT- Kubota 91 Mini Trackhoe DIMENSIONS: 24" x 11' DESCRIPTION '-4 43 60 0 BOTTOM oFCANYON ___ Stiff, moist, dark gray SANDY CLAY (CL) TOPSOIL/cOLLUVIUM 2— Very stiff to hard, moist,, olive-gray FINE SANDY CLAY (CL) - SANTIAGO FORMATION 4—, 5 ------- - BOTTOM OF TRENCH at 5' - No free groundwater encountered at time of excavation NOTE: Log representative of vertical section at - approximate mid-point of trench 7- 8- 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions locations at other or time. PROJECT NO.: 1317-SI01 L A R N I N P A R K FIGURE NO.: B - 9 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists TRENCU LOG LOGGED BY GS DATE EXCAVATED 11-27-90 SURFACE ELEVATION 168± feet TRENCH NO T - 3 EQUIPMENT: KUbota 91 Mifli .Trackhoi DIMENSIONS: 24" X 18 I DESCRIPTION - Stiff, damp, gray SANDY CLAY (CL) TOPSOIL LANDSLIDE 2- 3— . Stiff, damp, mottled tan/light broWn SILTY CLAY (CL) - . Stiff, damp, mottled brown/olive/gray SILTY CLAY CCL-CH), -, with càliche nodules,. and rounded clay frauents 5— remoLded clay seam with multiple shear surfaces 6— Hard, damp, olive-gray SILTY CLAY (CL) • with calióhe in joints - . .. SANTIAGO FORMATION 7_ BOTTCII OF TRENCH at 7.: - No free groundwater encoamtered at time of excavation NOTE: Log representative of vertical section at 8 approximate mid-point of trench 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times PROJECT NO.: 1317-SIO1 L ARW I N PAR K FIGURE NO.:. B - 1 0 ' GROUP DELTA CONSULTANTS, INC Engineers and Geologists tal TRENCH LOG LOGGED BY: GS. DATE ENCAVATED: 1127-90 SURFACE ELEVATION: 190± feet J TRENCH NO.: T- 4 EQUIPMENT: Kubota 91 MiniTrackhoe DIMENSIONS: 24" x 85' DESCRIPTION o A 114 28 - Stiff, damp, gray. SANDY CLAY (CL) TOPSOIL 1 - . LANDSLIDE 2— Loose to medium dense, damp, mottled tan/olive-gray CLAYEY - SAND (SC), with gray and tan c].aystone fragments 3- - - - 5tizz to Dare, damp, oLive-gray biLlY CLAY - highly fractured/sheared 5- 6- 7- - multiple shears- approximately l' thick remolded clay seam 8 - Hard, damp, olive gray SILTY CLAY (CL) - - - SANTIAGO FORMATION - BOTTOM OF TRENCH at 8'4" 9 - No free groundwater encountered at time of excavatioi NOTE: Log representative of vertical section at - approximate mid-point of trench 10 - Descriptions on this log apply only at the specific excavation Location and at the time the excavation was madej The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times PROJECT NO.: 1317-SIO1 L A R W I N P A R K FIGURE NO.: B - 1 1 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists TRENCH LOG LOGGED BY GS DATE EXCAVATED 11-27-90 SURFACE ELEVATION 236± feet TRENCH NO T - 5 EQUIPMENT: Kubota 91 Mini Trackhoe DDSIONS 24" x 18' 'DESCEIPTIOR 14 co - Stiff, damp, dark gray SANDY CLAY (CL) LANDSLIDE 1- 2- - becomes moist and soft with depth - Firm, moist, olive-gray SILTY CLAY (CL) - Stiff, moist, olive-gray SILTY CLAY (CL) fractured with remolded seams -I 1-inch-thick remolded clay seam at 5 feet of depth 5— - Hard, damp, olive-gray SILTY CLAY (CL) SANTIAGO FORMATION 6----- r . ••, BOTTOM OF TRENCH at 6 - lofree groundwater encountered at time of excavation NOTE: Log representative of vertical section at - approximate mid-point of trench 8- 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made The descriptions on this log are not warranted to be, representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SIO1 F L A R W IN P A R K j FIGURE NO.: B - 1 2 :I GROUP DELTA CONSULTANTS, INC. Engineers and Geologists TRENCH LOG LOGGED BY: 95 DATE EXCAVATED: 1127-90 SURFACE ELEVATION: 195± felt TRENCH NO.: T -.6 EQUIPMENT: Kubota 91 Mini Trackhoe DIMENSIONS: 24" x 11' DENCRIPYXON 43 94 W go - Very stiff, dry to damp, gray SANDY CLAY (CL) • TOPSOIL 1— Very stiff to hard, damp, olive-gray SILTY CLAY (CL) with 2 - subangular fragments of claystone throughout • LANDSLIDE 3- 4- 5- 6- 7- 8- - -t172-inch-thick remolded clay seam 9 - - - - Hard, damp, olive-gray SILTY CLAY (CH) SANTIAGO FORMATION - - - BOTTCtI OF TRENCH at 9' No free groundwater encountered at time of excavation NOTE: Log representative of vertical section at 10 - approximate mid-point of trench Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SI01 T L A R W I N P A R K 1 FIGURE NO.: B - 1 3 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists TRENCH LOG LOGGED BYi OR DATE CCVATED 112890 SURFAON ELEVATION 215± feet TRENCH NO T - 7 EQUIPMENT: Kubota 91 Mini Trackhoe DIMENSIONS: 24" x 8' ] DESCRIPTION I.1 Very stiff, dry to damp, gray SANDY CLAY (CL) - TOPSOIL 1- - Very stiff to hard, damp, olive-gray SILTY CLAY (CL-ON) SANTIAGO FORMATION BOTTl OF TRENCH at 4%' - No free groundwater encountered at time of excavation NOTEr LOg representative of vertical section at - approximate mid-point of trench 6— - 7- 8- 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation—was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PRO3T NO.: 1317-5I01 LARWIN P A R IC FIGURE NO.: B - 1 4 g GROUP DELTA CONSULTANTS, INC. Engineers.md Geologists TRENCH LOG LOGGED BY WEG DATE EXCAVATED 04-02-91 SURFACE ELEVATION 208 feet TRENCH NO EQUIPMENT: Kubota KR-SO DIMENSIONS: 24-inch bucket 43 b 64, DESCRIP.TIOI 53 IN - 1 5K Soft to very stiff, moist to wet, dark brown SILTY CLAY (CS) 1------ LANDSLIDE DEBRIS -2 PB 2—-- Soft, moist to wet, mottled gray-brown and red-brown SILTY TO FINE 3 - 3 PB SANDY CLAY (CS) Hard, damp to moist, gray-brown CLAYEY SILT (ME) 4- 4 PB 5 - - - 5 5K - highly fractured and disturbed 6 PB - - ch-thick shear seam - 7 SK EDefiwd,amp, light olive-tan FINE SANDY SILT (ML.) 8 PB SANTIAGO FORMATION 7 - - - - - BOTTOM OF TRENCH at 7 feet - No free groundwater encountered at time of excavation NOTE: Log representative of vertical section at 8 - approximate mid-point of trench 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SIO1 LARWIN P A R K FIGURE NO.: B - 1 5 GROUP DELTA CONSULTANTS, INC. 2 - . Engineers and Geologists TRENCH LOG LOGGED BY: MEG DAXE ENCAVATED: 04-02-91 SURFACE.ELEVATIONi 212 feet TRENCH NO.: T- 9 EQUIPMENT: Kubota ICH-90 DIMENSIONS: 24-inch bucket D H S C K I P T I 0 1 . .. In 03 W H so Soft to very stiff, moist, mottled dark brown and brown SILTY CLAY (CH) -1 SK TOPSOIL 1--- Fractured, very dense, dry, tan FINE SANDY SILT (ML) 2 -. SANTIAGO FORMATION 2 PB 3 --- - - - - B OTT Ct1 OF TRENCH at 3 feet - No free groundwater encountered at time of excavation 151R t.ng repraftantAMNra nf vrMrs1 ertion at - - 4 - approximate mid-point of trench 5- 6- 7- 8- 9- 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SI01 LARWIN P A R IC FIGURE NO.: B - 1 6 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists J TRENCH LOG LOGGED BY WEG DATE ENCAVATED 04-02-91 SURFACE ELEVATION 216 feet TRENCH NO T - 10 EQUIEMENT: ICubota ICR-GO DIMENSIONS 24-incb bucket - DESCRIPTION Soft to very stiff, moist, dark brown PINE SANDY CLAY (CS) - 1 SIC 1--- TOPSOIL 2 ------ - Hard to very stiff, moist, tan CLAYEY SILT (ML) - 2 SIC SANTIAGO FORMATION RV 3--- - Hard, damp to dry, tan CLAYEY SILT (ML) 4— BOTTOM OF TRENCH at 4 feet. 5 - No free groundwater encountered at time of excavation NOTE: Log representative of vertical section at - approximate mid-point of trench 6- 7- 6- 9- 10 - Descriptions on this log apply only at the specific excavation Location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SIO1 f LARWIN P A R K FIGURE NO.: B - 1 7 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists a I I a TRENCH LOG LOGGED BY WEG DATE CCAVATED 040291 SURFACE ELEVATION 240 feet TRENCH NO T - 1 1 EQUIPMENT: Kubota I-90 DIMENSIONS 24-inch bucket D K S C R I F 7 I 0 1 44 0. a • Soft to very stiff, moist, dark brown SILTY CLAY (CH) - 1 PB TOPSOIL 2--- Dense, damp, light brown FINE SANDY SILT (ML) 2 PB 3--- SANTIAGO FORMATION - Very dense, damp, very light gray SILTY FINE -3 PB RV 5 ---- - - - -. BOTTOM OF TRENCH at 5 feet - No free groundwater encountered at time of excavation NOTE: Log representative of vertical section at 6 - approximate mid-point of trench- 7 8 9 10 - Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not Warranted to bO representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SIO1 L A R W I N P A R IC J FIGURE NO.: B - 1 8 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists TRENCH LOG LOGGED BY: MEG. DATE EXCAVATED: 04-02-91 SURFACE ELEVATION: 240 feet, TRENCH NO.: T - 12 EQUI4ENT: Kubota KS-SO DIMENSIONS: 24-inch bucket • O z I IF DESCRIPTION El >4 El - 1 SK Hoist to Wet, mottled tan CLAYEY SAND (SC) 1----- FILL 2— Soft to firm, moist, dark brown SANDY CLAY (CL) TOPSOIL 3- - - - - Dense to very dense, moist, very iignt gray iLI1 iwii1t TO FINE SAND (SM) • SANTIAGO. FORM&TION - 2 5K 5--- 6----- - 3 SK 7----- 8 - - Hard, damp, light olive-gray CLAYEY SILT (NH) - -4 SK sotra't OF TRENCH at 9 feet - No free groundwater encountered at time of excavation NOTE: Log representative of vertical section at 10 - approximate mid-point of trench Descriptions on this log apply only at the specific excavation location and at the time the excavation was made. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SI01 L A R W I N P A R K FIGURE NO.: B - 1 9 GROUP.DELTA CONSULTANTS, INC. Engineers and Geologists LOG OF SLOPE LOGGED BY: WEG DATE: 04-02-91 ELEVATION: N/A LOG NO.: S - 1 EQUIRIENT: N/A - - DIMENSIONS: N/A HAMMER WT.: N/A DROP: N/A 1 h DESCRIPTION H r = - 10 . 15 - - Dense to very dense, damp, olive-gray SILTY FINE SAND (SM) SANTIAGO FORMATION Hard, damp, olive-gray CLAYEY SILT (ML/ME) - Hard, damp, olive-brown SILTY CLAY (CL/CU) becomes CL/SC - Dense, damp, light olive-gray SILTY PINE SAND (SM) becomes cleaner with depth - - Hard,. damp, light brown CLAYEY SILT (ML) - - 20 - = 25 - - 30 = - - Very stiff to hard, damp to moist, Light brown-gray SILTY CLAY (CL) - - Hard, damp, light olive-gray SILTY TO FINE SANDY CLAY (CL) - - Very dense, damp, light olive-gray to tan CLAYEY FINE SAND (SC to SC/CL) covered by sloughed soil below 27 feet TOE OF SLOPE 10 L... PB1 —I - - - - No groundwater seepage at time of inspection Descriptions on this log apply only at the specific location and at the time the logwas prepared. The descriptions on this log are not warranted to be representative of subsurface conditions at other locations or times. PROJECT NO.: 1317-SIO1 L A R W I N / P A R IC FIGURE NO.: B - 2 0 GROUP DELTA CONSULTANTS, INC. Engineers and Geologists APPENDIX C. SPECIFICATIONS FOR ENGINEERED FILL GROUP DELTA CONSULTANTS, INC. APPENDIX C SPECIFICATIONS. FOR ENGINEERED FILL These specifications present the usual and, minimum requirements for grading operations performed under observation and testing of Group Delta 'consultants, Inc. No deviation' from these Specifications will, be allowed, except where specifically superseded in the. preliminary geology and soils report, or in other .. written communication signed by the Geotechnical Engineer or Engineering Geologist. I. GENERAL The Geotechnical Engineer and Engineering Geologist are the Owner's or Builder's representative on the project. For fhp puvpps of these specifications., observation and testing by the Geotechnical Engineer includes' that observation and testing performed by any person or persons employed by, and responsible to, the licensed Geotechnical Engineer signing the soils report. All clearing, site preparation, or earthwork performed on the project shall be conducted by the Contractor under the observation of the Geotechnical Engineer. It is the Contractor's responsibility .to prepare the ground Surface to receive the fills to the satisfaction of the Geotechnical Engineer and to place, spread, IfljXE water, and compact the fill in accordance with the specifications of the Geotechnical Engineer. The Contractor shall, also remove all material considered unsatisfactory by the Geotechnical Engineer. It is also the Contractor's responsibility to have suitable and sufficient compaction equipment on the job site to handle the amount of fill being placed. If necessary1 excavation equipment will be shut down to permit completion of compaction. Sufficient watering apparatus will also be provided by the ContractOr, with due consideration for the fill material, rate of placement, and time of year. 1 GROUP DELTA CONSULTANTS, INC. E. A final report will be issued by the Geotechnical Engineer and Engineering Geologist attesting to the Contractor's conformance with these specifications. II. SITE PREPARATION U A. All vegetation and deleterious material such as rubbish and any construction debris from previous structures shall be disposed of off site. This removal must be - concluded prior to placing fill. The Geotechnical Engineer shall locate all houses, sheds, sewage disposal systems, large trees or structures on the site or on the grading plan to the best of his knowledge prior to preparing the ground surface. Soil, alluvium or rock materials determined by the Geotechnical Engineer as being unsuitable. for placement in compacted fills shall be removed and wasted from the site. Any material incorporated as a part of a compacted fill must be approved by the Geotechnical Engineer. D. After the ground surface to receive fill has been cleared, it shall be scarified, disced or bladed by the Contractor until it is uniform and free from ruts, hollows, hummocks or other uneven features which may prevent uniform compaction. The scarified ground surface shall then be brought to ' optimum moisture, mixed as required, and compacted as specified. If the scarified zone is greater than twelve inches in depth, the excess shall be removed and placed in lifts restricted to six inches. Prior to placing fill, the ground surface to receive fill shall be inspected, tested and: approved by the Geotechnical Engineer. E. Any abandoned buildings, foundations,, or underground structures such as cesspools, cisterns, mine shafts, tunnels, septic tanks, wells, pipe lines, or others not located prior to grading are to be removed or treated in a manner prescribed by the Geotechnical Engineer. 2 GROUP DELTA CONSULTANTS, INC. . III. COMPACTED FILLS A. Any material imported or excavated on the property may be utilized in the fill, provided each material has been determined to be suitable by the Geotechnical Engineer. Roots, tree branches, and other matter missed during clearing shall be removed from the fill as directed by __ the Geotechnical Engineer. B. Rock fragments less than six inches in diameter may be utilized in the fill provided: They are not placed in concentrated pockets. There is a; sufficient percentage of fine-grained material to surround the rocks. The distribution of the rocks is observed by the C. Rocks greater than.12 inches in diameter shall be taken off site. D. Material that is spongy, subject to decay, or otherwise considered unsuitable shall not be used in the compacted fill. E. Representative samples of materials to be utilized as compacted fill shall be analyzed in the laboratory by the Geotechnical. Engineer to determine their physical properties. If any material other than that previously tested is encountered during grading, the appropriate analysis of this material shall be conducted by the Geotechnical Engineer as soon as possible. F. Material used in the compacting process shall be evenly spread, watered or dried, processed and compacted in thin lifts not to exceed six inches in thickness to obtain a uniformly dense layer. The fill shall be placed and compacted on a horizontal plane, unless otherwise approved by the Geotechnical Engineer. G. If the moisture content or relative compaction varies from that required by the Geotechnical Engineer, the GROUP DELTA CONSULTANTS, INC. Contractor shall rework, the fill until: it is approved by the Geotechnical Engineer. H. Each layer shall be compacted to 90 percent (90%) of the. maximum density. in compliance with the testing method specified by the controlling governmental agency. (In general, ASTM D 1557=78 will be used.) IV. GRADING CONTROL A. Inspection of the fill placement Shall be provided by the Geotechnical Engineer during the., .pgesS• of grading. B.. In general, density tests should be made at intervals not exceeding two feet of.fill height for every 500. cubIc yards of fill placed. This criteria will vary depending 2 on the soil conditions and the size of the jobi in any event, an adequate ninnber of field density tests shall be. .......made...to.. wrify that... the . qtii being achieved. C Density tests should also be made on the surface material to receive fill as required by the Geotechnical Engineer. All cleanOut, processed ground to receive fill, key.. excavations, SubdrainS and rock dIsposal, must be inspected and approved by the. Géotechnical Engineer (and often by the governing authorities) prior to placing any fill. It shall be. the Contractor's responsibility to notify the Geotechnical Engineer and governing authorities when such areas are ready for inspectIon. V. CONSTRUCTION CONSIDERATIONS Subdrains shall be constructed as shown on the attached Figure c-i. Erosion control, measures,, when neCessary, shall be. provided by the Contractor during grading prior to the completion and construction of permanent drainage controls. Upon completion of grading and termination of observations by the Géotechnlcal Engineer, no further 4 GROUP DELTA CONSULTANTS, INC. filling or excavating, including that necessary for footings, foundations, large tree wells, retaining walls, or other features shall be performed without the approval of the Geotechnical Engineer or Engineering Geologist. D. Care shall be taken by the Contractor during final grading to preserve any bering, drainage terraces, interceptor swales, -or other devices of a permanent nature on or adjacent to the property. VI. ON-PAD. UTILITY TRENCH BACKFILL RECOMMENDATIONS A:. SHALLOW TRENCHES: (Maximum Trench Depth of 2 Feet). Use soils approved by the Geotechnical Engineer. The soils should be compacted to 90 percent of the inaximum dry density, as determined by ASTM Test Method D 1557=78, and* tested by the Geotechnical Engineer. Compaction by flooding or jetting will be. permitted only when, in the materials have a Sand Equivalent of at least 30 and the foundation materials will not soften or be damaged by the applied water. B. DEEP TRENCHES: . (Depth of Trench Greater than 2 Feet). The Soils should be compacted to 90 percent Of the maximum density, as determined by ASTM Test Method D 1557=78, and tested, by the Geotechnical Engineer. The backfill placement method should consist of mechanically compacting the backfill Soils •throughout the trench depth. If trench depth extends 5 feet, placement/ compaction, methOd should be reviewed by the Geotechnjcal Engineer. ContractOr should exercise1 and is responsible for, necessary and requIred safety precautions in all trench- ing Operations. a . C. TRENCHES UNDER VEHICLE' PAVEMENTS: A minimum of 3 feet of fill should be placed over conduit, apply criteria B, above. D. TRENCHES NEAR FOOTINGS.: Approved backfill soils must be mechanically compacted to 90 percent of the maximum density, as determined, by ASTM Test Method D 1557=78, and 5' GROUP DELTA CONSULTANTS, INC. LL3 tested by the Geotechflical Engineer. The general backf ill technique will be in accordance with the applicable criteria stated in A, above. E. REPORTING: If the Geotechnical Engineer will be providing a written opinion as to adequacy of soil compaction .and trench backfill, the entire operation should be performed under the Geotechnical Engineer's observation and testing. VII. GENERAL GUIDELINES FOR OVERSIZE ROCK DISPOSAL The following Oversize Rock Disposal Standard is to be used in all projects in which rocks larger than 12 Inches are to be incorporated into the engineering fill (see at Figure C-2). Placement of rock shall be in conformance with the City of Carlsbad Grading Ordinance, unless a variance has been obtained from the City in writing. All fills and preparation of subgrade must be approved by the Project Geotechnical Engineer. All fills must, be compacted to a minirnum 90 percent (90%) of the laboratory maximum density, as determined by ASTM D 1557-78, ZONE A: Shall be 10 feet minimum, measured vertically from finished grade, and 15 feet, measured horizontally, from the face. of the slope. In public right-of-wyS and easements, Zone A shall extend 1 foot below the deepest utility. Zone A shall consist of compacted soil only, with no rock fragments over 12 inches in maximum dimension, with at least 40 percent (40%) of the soil weight passing the 1/4-inch. sieve. ZONE B: Rocks over 12 inches, and less than 4 feet, in dimension, may either be individually placed or windrowed. For individual placement, rocks must be placed in excavations made in compacted And approved fill. The excavations shall be of a dimension such that sufficient space exists around the rock to allow flooding of free-draining granular material. Free-draining granular material shall be defined as on-site or imported Sandy soils, finer than a No. 4 sieve with, a Sand equivalent greater than 30. After placement and flooding of the granular material, Zone A material shall be placed around the rock and compacted. GROUP DELTA CONSULTANTS, INC. '1 .01 \i 10 —NATURAL GROUND ' '•A r —COLLUWUM and ALLUVIUM 4, REMOVAL: % a--- - NOTE FINAL 20' Cf BEDROCK / I I PIPE AT OUTLET SHALL BE NON-PERFORATED TYPICAL BENCHING ) fNL/NE TOWARD DRAIN SEE DETAIL BELOW ALTER MATERIAL TO MEET FOLLOWING SPECIFICATION OR APPROVED EQUAL: SiCvC SIZE P(RCVTAf PASINC 100 i/l a 90 ix 40-100 NO. 4 2540 N0 so NO. 5.0 0-7 NO. P.06 o-3 NOT(S ij iiNIMuu 601A. PERFORATED PIPE (PER. FORA TIONS 00 **A 2) ALL PIPE SICJLD BC RvC.(SCHWLE4O) OR APFOV(O S'JSSTITUT(1 WITH 11/N/MUM CRUSH/Ac STRENQTN OF 1000PSI. 3). 'FOR CoNrmcus RUN IN EXCESS Of 500 uSE8 D1A PIPE TYPICAL CANYON SUBDRA!N DETAIL Project No. 131 7-SI0 1 I LARWIN PARK DEVELOPMENT Figure c-i n +2' ROCK I I If 11 ) I I 10' MIN I I 7 ( TRENCH W/ROCK (LOCATED BELOW) I' +30 S.E. SOIL (FLOODED) A rA PI TRENCH PLAN VIEW ,,TRENCH EXCAVATED INTO COMPACTED FILL OR NATURAL GROUND FILL O.A. NATURAL GROUND - FINISH GRADE A/W TRENCH SECTION 3' MIN. ( LIflUTY ZONE A MATERIAL .. ,... •........•....... .•:- ::.:.........:: . :..• . 2 o o o o o o o o PAD SECTION ii ZONE% MAIRIA&ITI1 INDRIWED%VEIZE JCK 0 0 0 0 0 0 0 0 0 0 10'MIN 0 0 0 bIO 0 0 0 0 0. WINDROW (TYPICAL) 5' UN T. ZONE A; compacted soil only. No rock fragments over, 12. inches in maximum dimension. The upper 2 feet of Zone A material shall contain no rocks or other hard materials larger than 6 inches: in maXiifltm dimension.. ZONE B Rocks up to.4 feet in maximum dimension may be placed in this area. No rocks greater than 4 feet in maximum dimension can be used in. fills. OVERSIZE ROCK PLACEMENT Project No 7-SI01 I LARWIN PARK DEVELOPMENT Figure ,tI# - APPENDIX D PORTLAND CEMENT ASSOCIATION (PCA) INFORMATION SHEEP I9199T "REINFORCED CONCRETE TENNIS COURTS" F E GROUP DELTA CONSULTANTS, INC. ASSOCIATION Concrete 3 Concrete tennis courts at Broadmoor Hotel, Colorado Springs, Cob. The fast, uniform-texture surface of a concrete tennis court has, in the opinion of experts, contributed as much as any- thing toward the development of championship tennis play- ers. The true, even surface assures a consistently accurate bounce of the ball, a feature essential to superior play. Reinforced concrete is equally well adapted to both pri- vate and public outdoor courts, as little or no maintenance is required to keep the surface in playing condition. Prop- erly constructed, a portland cement concrete slab will en- dure many years of exposure to the weather under a variety of uses and continue to provide the paving surface neces- sary for good play. SITE SELECTION Traditionally, tennis courts in northern latitudes are ori- ented with the long axis placed in a north-south direction and the net running in an east-west direction. The United States Tennis Association (USTA) suggests that, south of the 42nd latitude, the long axis of the court be oriented .2 degrees counterclockwise of north so that the net runs somewhat from west-southwest to east-northeast. These placements are made to reduce the amount of direct sun- light in the players' eyes during prime playing time. Ground at the site should be reasonably level and urn. formly drained. The direction of surface drainage of the courts should be considered, and an examination of the site by a professional soil engineer may be warranted to- estab-lish its suitability for tennis courts. Other considerations include shelter from prevailing winds and space for future expansion. For championship play, courts should. be set away from trees that may cast shadows, shed leaves, or overhang the playing area. How- ever, for ordinary recreation games, there is no doubt that shade trees provide a welcome relief from a sweltering sun. Unless opaque curtains will be provided for the back- stops, the view beyond the court should be studied. High- ways and other traffic areas are distracting; light-colored buildings may also interfere with the concentrated vision required for tennis. A drinldng fountain and shaded benches or seats help to make a comfortable environment for those waiting to go onto the court or resting after a set. © Portland Cement Association 1976 SUBGRADE The subgrade is the natural ground, graded to the desired profile, on which the court is built,. i.e subgrade should be uniform, hard, and free from organic matter. If it is neces- sary to cut down trees in clearing the site, the roots should also be removed so that subsequent decay will not cause settlement of the court. The site should also be cleared of all sod, humus, and other rich organic matter. There usually is little opportunity to improve the sub- grade except by compaction and drainage. Tennis courts do not require strong support from the subgrade, but it is im- portant that the support be reasonably uniform with no abrupt changes from hard to soft. To construct a reason- ably uniform subgrade, special care must be taken to ensure. that there are, no weak areas, and that there is control of the major causes of nonuniform support: (1) expansive soils, (2) hard spots and soft spots, and (3) backfulling. Expansive soils.. Excessive differential shrinkage and swell- ing of high-volume change soils in a subgrade will create nonuniform support. As a result, the tennis court slab may become distorted and crackàd. For example, compaction of highly expansive soils when they are too dry can lead to detrimental expansion and softening of the subgrade; and if expansive soil subgrades are too wet prior to covering with a slab, subsequent drying and shrinkage of the soil may above standard optimum moistures minimizes subsequent changes in moisture and thereafter the subgrade will retaifl uniform stability. In addition, selective grading, crosshaul' ing and mixing of subgrade soils make it possible to obtain uniform conditions in the upper part of the subgrade Hard spots and soft spots. If the subgrade is not of uniform density throughout, the slab will tend to "ride" on the hard spots and bridge over the soft soil pockets. Special care must be taken to excavate and backfill those localized hard or soft spots with soils that match the surrounding soils. Moisture and density of the replacement soil should be sirn lIar to that of the adjacent soils. At the edges of the area, the replacement soil should be intermixed with soil frèm the adjoining grounds to-form a gradual transition zone. Backfilling. Where there are foundations and utility trenches, backfiuing should be done with soils like those surrounding the trench and compacted or consolidated 64n, layers to the same moisture and density as the sur- rounding material. Every attempt should be made to restore the original uniformity of the subgrade. SUBBASE OR CUSHION The subbase is a layer of material placód between the sub. grade and the tennis court pavement. Because a tennis court slab exerts very little pressure on the subgrade, it is seldom necessary or economical to provide a thick subbase. Minor American Society for Testing and Materials Designation D698. , .- i'_. - -- -- .. -- -r. •. -7-.:-:- : ,.----.. - - -..-. .. -:. -:' - - - -- ..... -: ..-.-- : The subgrade and subbase should be of uniform qualfty changes in subgrade pressures have a minor effect upon the thickness of a concrete slab for given loading conditions. Since uniform support rather than strong support is the most important function of subgrades and subbases for con- crete slabs on grade, it follows that the slab strength is achieved most economically by building strength into the• concrete useit The primary function of a subbase under highway pave. ments is to prevent mud-pumping of fine-grained soils. A function of a subbase under a floor is to serve as a capillary. action barrier. In the case of a tennis court, neither of these functions is important; the subbase merely serves as a level. ing course for fine grading, and as a cushion for obtaining uniform support by equalizing minor surface irregularities. Thus, it is possible to construct a satisfactory tennis court without any Subbase. Where subbases are needed, a thin layer-.4 in. or less—is suggested. SUBSURFACE DRAINAGE The purpose of artificial drainage is to avoid pools of stand- ing water, to reduce uneven frost heave, and to afford fast surface drainage of the courts after a downpour so that play can resume as quickly as possible. If the site does not have good drainage, concrete drain tile should be provided in a trench at the perimeter of the court. The trench is placed at or near the edge of the slab to a depth of several feet, and the bottom sloped about 1 in. every 10 ft to natural drainage or a storm sewer. Concrete drain tile is laid with open joints that are covered with roof- ing felt or other suitable materials to prevent soil or dirt from- entering after backfilling. Coarse gravel or crushed stone, ranging in size from 1 to 1½ in., should be placed over the drain tile to a depth of-at least 12 in. Above that point, a filter-grade sand can be used up to the required grade. If the courts are on the side of a hill, it may be suffi- cient to provide drainage or a cutoff wall on the uphill side only. (Sloping the court surfaces for runoff of rain water is discussed below.) 1• 13 181-011 21'- 0° L 21'- 0" 181 -011 78.-o 11 I 16'- 0" to 21'-O" J!:t o 16'-d' to 21 K) to 12 ft. high fencing (Backstop) : II Post__..._J III'-6" to I2l'-6" Concrete Dimensions for pointed lines are from outside to outside except for center 1ire Fig. 1. Layout of single reinforced concrete tennis court. The larger dimensions shown for the distance to backstops and sidestops are USIA regulation court dimensions for tournament play. 121'- 6' Concrete 121'-O" 39'-O" 396-0 + 2' On 9. LAYOUT The layout of a single tournament court is given in Fig. 1. This shows the regulation playing area of 60x 120 ft inside the fencing. Where space or funds are limited, as for a pri- vate court at a residence, a playing surface 52x1 10 ft may be satisfactory. For a bank of courts, a space of 10 to 12 ft is allowed between courts. A pair of courts is illustrated in Fig. 2. In this case, no fence is provided between courts. If a fence is. desired between courts, 10 or 12 ft should be allowed be. tween the fence and the side playing lines. Outdoor courts made of nonporous materials such as concrete should be built to a pitch of I in. in every 10 ft, with the entire playing area in the same plane. The two halves of the court should not both be pitched to or from the net, because this would, in effect, change the height of the net. Preferably, the entire court should be pitched from side to side. The USIA discourages construction of courts pitched end to end because the lower court will remain wet longer after a rain. In the case of two courts, as in Fig. 2, the pitch of each court can be toward the outer edge; this avoids a valley or drain between the courts. PeGk to In a. -IO ft. high fencing (Backstop) Fig. 2. Layout and spacing for a pair of courts. Other directions of slope for outdoor courts are possible. 3 Warping of the court slabs to achieve a pitch in a valley is not permitted by the USIA. On the other hand, the courts can be pitched at an angle (Fig. 3), and this will pro- duce a pitch in the valley. Sloping a court is merely a matter of convenience to drain any rain water. It has nothing to do with tournament rules as long as the entire court is in a continuous plane; indoor courts are built dead level. Thus, in the case of a bank of three courts, there are other ways to slope the courts than shown in Fig. 3. For example, the center court could be dead level and the two outer courts could be sloped down to the outer edges. Likewise, the courts can be sloped directly to the sides, but drain inlets would be needed in the dead-level valley to hasten drainage there. TYPES OF CONCRETE COURTS Concrete tennis courts 'are constructed in various ways depending on the available funds and the contractor's con- struction preferences or capabilities. The type recommend- ed for most installations is termed continuously reinforced. I2I'-6' Concrete _ 39'-0" , 39'—O'. f 2r_ o 4 _IH I'iycned —IO ft. high fencing (Backstop) F. 3. Layout and spacing for a bank of three outdoor courts. The slopes shown avoid the need for drain inlets between courts (and drain tile beneath the slabs) while maintaining each entire court in a continuously pitched plane. It has reinforcing bars throughout and is joint-free in the playing area. If the concrete is continuously cast over the entire court, no joints are required; if concrete is continu- ously cast over only one-half of the court, an expansion joint should be provided in the slab under the net. If two or more courts are constructed,. expansion joints should be provided -midway between courts. Slab and joint details for this continuously reinforced type of court are shown in Fig. 4d; other typical tennis court details are shown in Fig. 4. These large slabs are strengthened in each direction with reinforcing steel bars having an area equal to ½ of 1% of the concrete cross-section area. This amount of reinforàement will hold shrinkage cracks tightly together and eliminate any differential vertical movements at the cracks. Concrete tennis courts containing this percentage of reinforcement will retain a smooth, playable surface for many years. The specifications at the end of this publication are for this type of court. The second type is the jointed court shown in Fig. S. The court proper within the playing lines constitutes about half of the total paved area. It is reinforced with bars and has no joints, while the remainder of the court, where the bounce of the ball is not critical, has mesh reinforcing and control joints. Thus a savings in materials is effected, and many contractors find this to be an easier and less costly way to build a court. When an integrally colored concrete topping is to be applied, the control joints are placed at the outside edge of the playing lines. Otherwise, joints are pref- erably placed about a foot outside of the service and base stead of using sawn or tooled joints at SeGtions B.B in Fig. 5, these control joints can be formed as in Section A-A, and reinforced with steel mesh alone. If desired, joints at A-A can be sawn or tooled, but a formed joint with a bond- breaker is preferred there. A third type of concrete court is the prestressed court. It is built with prestressing steel strands and is usually more expensive than the other types. The concrete is post-ten- sioned to a compressive stress of about 300 psi, and this counters the tendency to shrinkage cracking. A slab 122x205 ft for a bank of four courts can be constructed in this manner without any joints. The advantage of this large, unjointed slab is that it can be sprayed and used as a natural ice surface for winter skating. An artificial ice surface can be made by installing refrigeration coils in the concrete. Another advantage of this type of court is that the large paved area without joints or cracks is well suited for roller skating. In the three types of concrete courts just described, it is assumed that there will be no other construction joints, be- cause these have a tendency to develop a slight raveling that would interfere with the uniform surface texture needed for a tennis court. If emergency construction operations do require a construction joint, it should be formed with a bulkhead as shown in section A-A of Fig. 5, but bond should be developed at the interface. Fig. 4 (opposite pagej. Details of concrete tennis courts. The rein-forcement shown for the slab is for the continuously reinforced type of court, with no joints except under the net and between ( ) courts. 211 wrought R I Slab thicknessi see Detail 40 e) Cross section $ IL k'" Screw anchor ID and eyeball AL 12" x 12" x 12" Concrete anchor a) Tiedown for center of net I I 1_ackstop line 154" Gage fencing - 3/"Cork I joint material Reinforced concrete slab Subgrade _ a I.. __ 91_9N eye bolt. , •Roinfcrcem 1w 3'-O" mm. Concreté tile drains (To be installed when required by local conditions) 2" Wrought iron pipe 34" Expansion joint 20- via. M. Concrete foundation - 2" C.I. pipe terminates— from surface of court I b) Detail at removable net post p i4ü..ut ..de1 •.l. Where two or more courts adjoin, this detail would also apply. 5 Reinforcing bors, each way is P. o.c. for 5' thick slob @ " c.c. for 4" thick slob ,Elostomeric sealing f compound 7/8 T=i--=- Slab bolsters with said Nonextruding plates 40" O.C. expansion joint or concrete bricks filler material 3-0" O.C. each way. d) Slab and expansion joint detaile I 9'-9" tennis Building paper Concrete foundation c) Detail at fencing (Backstop) 5 I2l'-6 - Expansion _°'(S..Fi 4d)\ of not fine ~Ccnfrat 01 IJIII .111 1-IL I I - - -1 - - 1± TIt2T: see: 'l * text See - /M A F AS nside the playing lines' Outside of the Playing lines' ''5 rebors welded wire fabric 6 12" o.C. for 5" slob 6 x 6 - W4.O a W4.O for 5" slob 15" o.c. for 4" slab 6z6 -W.9 a W2.9 for 4" slob ,." Radius. edged b.fai, / Iimovmg bulkiwod Alternate bum itcoherl 1-6 Reint bars Altentate bars Oct as dowels _ _ C goo t'ar sueponts as Apply for CII or Welded win eluwn in Fig 4d other band breaker fabric Section A-A Min..—.*I— /( Moe. saw cut width Welded wire fabriC /4 Min. ,4' Radius haàd-tooled joint Alternate Sections B-B p Method of lopping welded wire fabric eir.T.-I jk1IV • IL&1LA - Fig. S. LayOut for a jointed type of court with control joints in the slab outside of the court proper, offering some possible economies in construction. Further economy can be achieved by using the smaller court dimensions shown in Fig. 1. SLAB THICKNESS A 5-in.-thick tennis court slab is recommended for outdoor courts in severe climates such as in Wyoming, Iowa, and Ohio. A 4-in.-thick slab is recommended in mild climates, such as Florida and the coastal areas of California and Texas. The choice of concrete thickness in other areas is a matter of judgment. Many factors influence the required thickness of the concrete slab. These include the range of temperature change, moisture variations in the slab, drying and carbona- tion shrinkage of the concrete, expansive soils, any nonuni- formity of the subgrade support, and quality of construc- tion. The more movement and rotation that occurs at the cracks, the greater will be the amount of raveling. A thicker slab will have less of this distress. Moreover, a thicker slab will have more concrete cover over the reinforcing bars and will lessen the chance of spalling due to rusting of the bars. A tennis court slab should have a large area relatively free of blemishes for many years. A certain amount of fine cracking can be expected, but with the steel specified above, the cracks will be tightly held together. Quality of concrete. It is important that the correct quality of concrete be specified and used. The concrete must have durability to withstand the extremes of weather and the in- gredients must be selected so that the concrete can be read- ily placed and finished. For these reasons, the following rec- ommendatioñs are made: Maximum-size aggregate (gravel, crushed stone, etc.) should not exceed 1/3 of the slab thickness: 4-in, slabs can use 3/4 or I-in, top size, but 1 in. is recommend- ed. Slabs of 5-in, thickness can use any of the sizes shown in Table 1, but 1.1/2 in. is preferred. The coarse aggregate in some localities contains appreci- able amounts of chert, a soft stone that splits during freezing or under extreme atmospheric conditions, causing popouts, or small conical upheavals over the stones, at the surface of the slab. While a small amount of this aggregate may otherwise conform with ordinary concrete specifications, the popouts diminish the uniform smoothness of the tennis court surface. A chert.free aggregate can be specified if this situation must be avoided. Chert-free aggregate (or beneficiate4 aggregate) is somewhat costly if used for the full slab thickness, but this expense can be reduced by using it only in a bonded topping slab, and, particularly, only in the court proper Minimum cement content should be no less than the amount given in Table I for the particular maximum- size aggregate used. These cement contents are essen- tial for proper finishing and strength development. ( L Table 1. Guide for Ordering Ready Mixed Concrete for OutdoOr Tennis Courts in Freezing Climates Maximum- Minimum Compressive Air size cement Maximum strength content. aggregate. content. slump, at 28 days, percent by in. lb per Cu yd in. psi volume 3/8 610 4 3,500 7-1/2 ± 1 1/2 590 4 3.500 7-112±1 3/4 540 4 . 3.500 6 ±1 1 520 4 3.500 6 ±1 1-1/2 470 4 3,500 5 ±1 'in areas exposed to a number of freeze-thaw cycles, it is advisable to use a minimum cement content of 560 lb per cubic yard. Maximum slump should not exceed 4 in. This value includes the tolerance. A 4-in, slump will give a good, workable mix. Stiffer mixes are harder to place and finish by hand methods, but can be used to advantage with mechanical placing and futishing equipment. Very Wet, soupy mixes will not make durable con- crete and have, excessive shrinkage cracking. compressive sweflgth at 28 days should be no less than 3,500 psi. In some instances, a cement content higher than that given, in Table 1 may be necessary to obtain 3,500-psi concrete.. good durability in all concrete exposed to freezing and thawing cycles, When this freezing protection is not required, air . content of 2% is useful to reduce bleeding and segregation and improve workability and finishability. Reinforcing steel. Reinforcing bars are used to hold any concrete cracks tightly together so that they do not inter- fere with the bounce of the ball or the footwork of the players. Reinforcing bars must have deformations of certain sizes, as described in the ASTM specifications, in order to bond properly with the concrete. At the time concrete is placed, reinforcement should be free of mud, oil, or other coatings that would adversely affect bonding capacity. On the other hand, a light coat of mill-scale rust is, permitted on the bars. The reinforcing bars should be placed at the center or middepth of the slab and, if they are to function properly, some positive measure must be taken to hold them in that position. They should be tied together with soft iron wire and supported on slab bolsters or concrete bricks as shown in Fig. 4d. The bars should be lapped at least 18 in. in order to transfer the stress from one bar to the other, and the laps should be staggered. In the case of mesh or welded-wire fabric, support acces- sories must be more closely spaced because the wire will easily bend out of shape under the weight of a man. The practice of laying the mesh on the subbase or subgrade and pulling it up after concrete has been placed is not recom- mended because there is no assurance that the mesh will come to rest in the concrete in straight, lengths or at the proper level. On the other hand, the mesh can be placed by "walking it In.' This involves placing concrete just 'a few inches thick, laying the mesh, and then placing the remain- der of the concrete. Since there is an elemetit of risk in- volved in this procedure, foot traffic in the fresh concrete after' laying mesh should be held to an absolute minimum. Transporting and spreading. Fresh concrete can be trans- ported by buggy on wooden runways, by crane and bucket, by conv?yor belt, or by pumping,* Bridge deck payers have also been used and are ideal for achieving a good finish on a tennis court Concrete should not be spread by spud vibra- tors, but by shovels or special rakes. Screeding and consolidation. Of all the slab placing and fin- ishing operations, screeding has the greatest effect on sur- face tolerances. Wet screeds or pipe screeds may be used. The use of jitterbugs (flat or cylindrical grating) to con- solidate the concrete is not necessary or desirable and should be avoided. However, their use is permissible if the slump is I in. or less. The practical way to consolidate the concrete in a 4- or 5-in..-thick tennis court slab is with a vibrating strikeoff. This gives positive control of the screed- ing operation and saves a great deal of labor. This method is recommended when the slump is less than 3 in For higher slumps, hand strikeoff methods are suggested. .To be effective, a vibrating strikeoff should have a large amplitude and a frequency in the range of 3,000 to 6,000 vibrations per minute (50 to 100 hertz). Periodic checkups effective. This subject is treated in ACI Standard 309-72, Recommended Practice for Consolidation of Concrete. FINISHING Immediately following screeding, the concrete is further leveled with a darby or bullfloat to fill in the ridges and surface voids. Following this there is a slight wait for stiff- ening of the concrete until the surface will sustain a foot pressure with only about 1/4-in, indentation, and until all• bleed water or excess moisture hEs left or been removed from the surface. Edging is required at control joints if the jointed courts shown in Fig. 5 are chosen. The edging tool has a 1/8-in. radius, producing an edge that is less vulnerable to chipping. The slab is then floated to (I) embed large aggregate just beneath the surface: (2) remove slight imperfections, humps, and voids, and produce a level or plane surface; and (3) compact the concrete and consolidate mortar at the sur- face in preparation for other finishing operations. The final finish of the concrete is very important to the play of the tennis ball. Too rough a finish will slow the ball and footwork, and cause excessive wear on balls and shoes: too slick a finish gives too little spin and bounce and makes footing less sure. Uniformity of the surface texture is also important. A proper finish can be achieved with a swirl pat- terfl, produced with the flat of a trowel moved in small cir- cular movements. A light broom finish is equally suitable. 'See Concrete Constnsctiôn Practices, ISO 191. Portland Cement Association, 1974. . 7 C. By using the flat of the trowel in nnaU circular movements, a swirl pattern will be produced. A wavy texture male with a fine-hair broom makes a good tennis court finish. Uniformity of texture is important. Coarse textures are produced by wood floats, and medi- um textures by aluminum, magnesium, or canvas resin floats. A finetexturid swirl is obtained with a steel trowel. A broom finish is obtained by pulling damp brooms across tures are obtained by using soft-bristle brooms on floated or steel-troweled surfaces. Best results are obtained by using a broom that is specially made for texturing concrete. To be certain that the finish will satisfy an athletic direc- tor or tennis pro, the surface can be made slightly rougher than necessary and reduced to the desired texture by a light grinding after curing. When hot weather causes a rapid evaporation of water from the slab, any delay in getting the slab protected by curing compounds or other water-retaining materials can result in plastic shrinkage cracking, low surface strength, dusting, and early deterioration. Regardless of the weather it is recommended that troweling be kept to the minimum necessary to obtain the desired finish. Of course, if a color coating is to be applied that is 1/16 in. or more .thick, it will furnish its own texture, and all that is required on the concrete is a light broom or steel- trowel finish. CURING The purpose of curing is to maintain conditions under which concrete hardens by keeping it moist and warm. Moist cur- ing is done in a number of ways: with wet coverings, sprin- kling, or ponding to offset loss of moisture; or by sealing the concrete surface with plastic sheeting or waterproof paper. A curing compound is not recommended on a tennis court because it may inhibit bond between the concrete and the paint for the playing lines or for applied surface color coatings. Supplying additional water is the most effective curing method. Burlap, a commonly used wet covering, should be free of any substance that may be harmful to concrete or cause discoloration. New burlap should be washed before hard enough to withstand surface damage and sprinkled fre- quently to keep the concrete surface continuously moist. Water curing with lawn sprinklers, nozzles, or soaking hoses must be continuous so that there is no chance of alternate wetting and drying during the curing period. Ponding is practical for tennis courts. Sand or earth dikes are used to confine water on the slab. In the case of an outdoor slab that is pitched 1 in. in 10 ft, terraced pond- ing is practical to minimize the depth of water needed. A sufficient depth of water must be maintained to prevent dry spots. Curing methods intended to seal the surface are not quite as effective as methods that supply water, but they are widely used for their convenience. Moisture barriers such as plastic sheeting and waterproof paper are popular. They do not require periodic additions of water, but they must be Laid flat, completely sealed at laps, and anchored adequately along edges. Curing with these materials may cause patchy discoloration, especially if the concrete con- tains calcium chloride and has been finished by hard steel troweling. Discoloration takes place when the plastic or paper becomes wrinkled. It is difficult and time consuming on a large project to smooth out the wrinkles that may form. Accordingly, other means of curing should be used when uniform color of a concrete surface is important. The curing period should be started as soon as it is pos- sible to do so without damaging the surface. It should con- tinue for a period of 5 days in warm weather (70°F or high- er) or 7 days in cooler weather (50°F to 70°F). The tem- perature of the concrete must not be allowed to fall below 50°F during the curing period. C. 8 4 Moist curing of concrete is necessary to assure adequate hydration of the portland cement. In this case plastic sheeting is used to hold the moisture in the concrete.. Ideally, tennis courts should be built well in advance of cold weather. When placed during warm weather, there is plenty of time for concrete to develop strength to resist freezing and thawing. Also it is more practical to cure by ponding and so avoid the patchy discoloration mentioned above. During cold weather the following precautions should be taken: Heated concrete should be ordered so that the tem- perature of the mix does not fall below 507 during plac. ing, finishing, and curing. When there is danger of freezing, particularly when average daily temperatures are below 40°F, concrete should be kept warm during curing. Insulat- ing blankets or 12 to 24 in. of dry straw can be used. Straw should be covered with canvas, waterproof paper, or plastic sheeting to keep it dry and in place. The effectiveness of the protection can be checked by placing a thermometer under the covering. Slab edges and corners are most vulner- able to freezing and should be carefully protected. High-early-strength concrete may also be used to speed up setting time and strength development during cold peri- ods. This can reduce the curing period from 7 to 3 days, but a minimum temperature of 50°F must be maintained in the concrete for the 3 days. High-early-strength concrete is made by using (1) Type III (high-early-strength) cement, (2) an extra 100 lb of Type I cement in each cubic yard of concrete, or (3) up to 2% calcium chloride by weight of cement. Due to problems that may occur with use of chlo- rides, method 1 or 2 is recommended. In hot weather, precautions may be required to prevent rapid loss of surface moisture from the concrete. Hot weather can cause finishing difficulties and cracks (known as plastic shrinkage cracks) in the fresh concrete soon after placing. Some helpful measures to prevent these problems are: (I) dampening the subgrade; (2) minimizing finishing time by having sufficient manpower and equipment on hand; (3) erecting sunshades and windbreaks; (4) using tem- porary coverings such as wet burlap or plastic sheeting dur- ing finishing and uncovering only a small area at a time just ahead of the finishers; (5) using light fog sprays or a mono- molecular film to prevent evaporation from the concrete; and (6) starting curing as soon as possible. During very hot. dry weather, consideration should be given to placing and finishing during the cooler, early morning or late evening hours. SAWCUT JOINTS The control joints shown in Fig. 5 can be cut with a power saw. An electric orgasoline-driven power saw fitted with an abrasive or diamond blade is used. Joints made with a power blade are usually cut within 4 to 12 hours after the slab has been placed and finished and particularly before the air temperature drops appreciably. Joints should be cut as soon as the concrete surface is firm enough not to be torn or damaged by the blade. Otherwise very fine random shrinkage, cracks can form in the concrete slab, or cracks may be generated during sawing that run off toward the edge at an angle to the saw cut. DETAILS Net posts must be firmly anchored to resist frost heave and the tension of the net. The concrete slab provides excellent resistance to the constant lateral pull of the net cable. The center tiedown of the net requires firm anchorage as shown in Fig. 4a. an expansion joint material isolating them from the Con- crete slab. This is to avoid the straining and cracking of the concrete that could occur from movements caused by tem- perature changes, drying shrinkage, and frost heave. To make ball retrieval easy, fencing is run down to the surface of the concrete. ARTIFICIAL LIGHTING Nighttime lighting of outdoor courts will provide a recrea- tional outlet and will greatly increase the total volume of play. Comprehensive recommendations and instructions for lighting tennis courts are given by the Illuminating Engi- neering Society, New York City, in its publication, Tennis Court Lighting. 9 Artificial lighting lengthens the day and gives more players a chance to get on the enurts. T h e W a v e l a n d T e n n i s C o u r t s i n L i n c o l n P a r k , C h i c a g o , shown here, are the jointed type. They were constructed in a manner similar to that shown in Fig. 5, and used a monolithically colored concrete topping bonded to a base slab. Guide Specifications for Construction of ReinforcedConcrete Tennis Courts These specifications* are intended to accompany drawings that show plan and sections of the court(s) with all neces- sary dimensions,, levels, slopes, special details, and layouts of dra in age, if any. The specifications may be copied without obtaining per- mission. 1. General Requirements The work shall be done in a thorough, workmanlike man- ner. Any reference to a specification or standard of the American Society for Testing and Materials (ASTM) or the United States Tennis Association (USIA) refers to the edition that was effective six months prior to the contract date. 2 Site Inspection and Subgrade, Subbase Preparation a. Clearing and Grubbing. Trees and other large vegeta- tion including their root systems to a depth of not less than 12 in. shall be removed from the site and the soil treated with a sterilant that will effectively inhibit future growth of flora. 'Specifications are for the continuously reinforced courts rec- ommnded and described on page 4. The Portland Cement Associ- ation wishes to acknowledge the counsel of the U.S. Tennis Court and Track Builders Association in the development of these specifi- cations. Excm'ation and Filling. The site shall be excavated I and/or filled so as to provide the finished grades shown on drawings for the tennis court areas. Exca- vated areas occurring directly under and adjacent to tennis court areas shall be compacted to the same den- sity required for the fill material specified herein. Fill Material. Fill material where required shall be as approved by the owner or his representative and shall be placed in layers not exceeding 6 in. each in thick- ness and compacted to 95% standard density at opti- mum moisture in accordance with ASTM D698, Test for Moisture-Density Relations of Soils Using 5.5-lb Rammer and 12-in. Drop, (except that high-volume change soils shall be compacted at 1% to 3% above optimum). Subgrade. The subgrade shall be shaped to a line and grade as shown on the drawings. Surface of the sub- grade shall be not more than 3/4 in. above or below the subgrade elevation shown on the drawings. Subbase or Cushion. Subbase material under paved areas shall consist of clean sand, gravel, or crushed stone as indicated on the drawings and be free from clay, lumps, rocks, or other deleterious material. Thickness shall be as indicated on the drawings and shall be compacted to 95% standard density at opti- tions. mum moisture in accordance with ASTM D698 to minimize displacement during construction opera- ( 10 3. Storm Drainage Provisions Interceptor Drainage System.. A peripheral drainage system shall be installed (if detailed on the drawings) so as to intercept and drain either surface or subsur- face water that would otherwise flow over or under the court(s). Trench Backfills. Any trench backfill areas occurring under or adjacent to tennis court areas shall be com- posed of the same material as the surrounding soil, compacted in 6-in, layers to the same density as the surrounding soil. 4. Slope All excavating, filling, compacting, grading, and leveling work required hereunder shall be performed so that each entire finished outdoor court surface slopes I in. for each 10 ft in a true plane as indicated on the drawings. No warped surfaces will be permitted. 5 Concrete Constniction a. Cement. Cement shall conform to one of the follow- ing: Standard Specifications for Portland Cement, ASTM C150, or Specifications for Blended Hydraulic Cements, ASTM C595, excluding slag cements Types S and SA. of concrete placing shall be free of loose, flaky rust and other coatings or films that could interfere with bonding to the concrete. Forms and Screeds Forms and screeds shall be accu- rately set to the lines and grades indicated on the drawings, firmly supported on the subbase or sub- grade, and securely staked to prevent settlement or movement during placing of concrete. Forms shall re- main in place, until the concrete has taken its final set. Joints. A nonextruding expansion joint filler material 3/4-in. thick shall be installed at the net line (if the two halves of the court are cast separately) and be- tween courts. Bottom edge of the filler material shall extend to or slightly below bottom of slab; top edge shall be held 7/8 in. below surface of the slab by a tack strip of wood with its top flush with the finished slab surface. Edges of joints shall be tooled with an edging tool.. After concrete has cured, tack strips shall be removed and the joints sealed with an elastomeric sealing compound to within 1/8 in. of the surface. Concrete Proportioning and Mixing. The concrete shall have a compressive strength of not less than 3,500 psi at 28 days after casting. The minimum cement content for finishabiity shall be not less than: Minimum cement content, Maximum-size coarse lb per cu yd aggregate, in. LAr Entrainment. Air entrainment, by total volume of 610 3/8 concrete, shall be: 590 1/2 IF 63% to 8% for 3/8- or 1/2-in. max.-size coarse awe- 540 3/4 ( CIA I gate; ..- 5% to 7% for 3/4- or 1-in. max.-size coarse aggregate; 4% to 6% for 1-1/2-in. max.-size coarse aggregate. Aggregate. Aggregate shall conform to Standard Speci- fications for Concrete Aggregates, ASTM C33. For concrete work that is 5 in. thick, the nominal size of the coarse aggregate shall not exceed 1-1/2 in. and for concrete work that is 4 in. thick, the nominal size of the coarse aggregate shall not be greated than 1 in. Thiclaiess of Concrete. The concrete court slab shall have the thickness noted in the contract documents. If no thickness is specified, the concrete court slab shall be5in. thick. Reinforcement. Steel reinforcement bars shall con- form to Standard Specifications for Deformed and Plain Billet-Steel Bars for Concrete Reinforcement, ASTM A615, Grade 60 or 40. For a concrete slab that is 5 in, thick the bars.shall be No. 5 size in both direc- tions at 12 in. on center. For a concrete slab that is 4 in. thick the bars shall be No. 5 size in both directions at 15 in. on center. Bars shall be accurately positioned at middepth terminating 2 in. away from edges and joints, and shall be adequately supported by concrete bricks or by chairs with sand plates provided to pre- vent bar supports from sinking into the subbase. Bars shall be lapped 18 in. and also ,securely tied or other- wise secured so that there is no possibility of displace- ment when concrete is placed. Reinforcement at time 470 1-1/2 In freeze-thaw environments, the minimum cement content shall be not less than 560 lb per cubic yard. The slump shall be not more than 4 in. Ready mixed concrete shall be mixed and delivered in accordance with ASTM C94, Specification for Ready Mixed Con- crete. Placing and Finishing. Concrete shall' be continuously placed over one half of the court or over the full court. Expansion joints shall occur only at the net line and/or midway between courts. No control joints shall be provided, and construction joints shall be installed within the court only under emergency conditions, but shall not be edged. Concrete shall be carefully spread, consolidated, screeded, floated, and finished. After having taken initial set sufficient td sustain foot pressure with only about 1/4-in. indentation and after the water sheen has left the surface, the slab shall be uniformly finished by power floating and troweling. The final finish texture for an exposed concrete sur- face shall be a light broom finish applied parallel to the net line, or a swirl pattern produced by the flat of a steel trowel in small circular movements. Surface Tolerances. The concrete surface shall be fin- ished to a tolerance of 1/8 in. measured as the depar- ture from the testing edge of a 10-ft straightedge held parallel to and in contact with the surface. 11