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HomeMy WebLinkAboutCDP 15-23; LANIKAI LANE; PRELIMINARY PAVEMENT SECTION DESIGN AND PLAN REVIEW; 2018-09-28Project No. FC-18-08-147 September 28, 2018 Core Capita Investments Mr. Troy Shadian 17780 Fitch, Suite 145 Irvine, California 92614 §M§ GEOTECHNJCAL SOLUTIONS, INC. Consulting Geotechnical Engineers & Geologists 5931 Sea Lion Place, Suite 109 Carlsbad, California 92010 Office: 760-602-7815 smsgeosol.inc@gmail.com ' ... Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad, California (Drawing No. 504-9A) Our firm has been retained to provide field engineering observations and laboratory and compaction testing services during the construction for the proposed main gate improvement project at the above referenced property. We have also received and reviewed the project Grading Plans, prepared by Hofman Planning & Engineering, dated August 23, 2018. The purpose ofthis transmittal was to review the project grading plans from a geotechnical standpoint, and provide preliminary subgrade preparations and pavement section designs, based on our past experience with similar subgrade soils in the vicinity of the project site. A detailed subsoil investigation, soil sampling and laboratory testing is currently not completed for the project with actual soil sampling and testing planned at the time of demolition and construction works. However, we have visited the site and have assumed conservative minimum subgrade R- value and expansion properties for onsite subgrade soils based on surface observations and our past experience in the project areas. Consequently, all geotechnical recommendations provided in the following sections shall be considered preliminary for planning and cost estimating purposes only, subject to verification and revisions based on actual sampling and laboratory testing that will be performed at the beginning of the project construction works. Revised recommendations may be necessary and should be anticipated. Based on our review of the project plans majority of the planned improvements are proposed at Main Gate 1 and will include new pervious Permeable Interlocking Concrete Pavers (PICP), saw cutting and resurfacing of existing asphalt concrete pavings with new HMA (AC), new PCC sidewalks, new pedestaling ramp, new concrete curbs and new metal sliding gate. Improvements at Gate 2 primarily consist of new metal sliding gate. Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad September 28, 2018 Page2 I. ANTICIPATED SUBGRADE SOILS PROPERTIES The project improvement areas may be anticipated to be underlain by natural to disturbed/reworked natural ground surfaces, consisting of orange to tan brown sand to silty sand (SM/SP) deposits common in coastal Carlsbad areas. Engineering properties of the site subgrade soils may also be anticipated to consist of expansion potential in a very low to low range (Expansion Index less than 50) and subgrade R-value greater than 5. Assumed values shall be verbified at the time demolitions and construction based on actual sampling and testing. II. GRADING PLAN REVIEW Based on our review and from a geotechnical viewpoint, the project grading plans propose a feasible design for the planned new site improvements, and are acceptable us. However, this report should be considered as a part of the project grading plans, and all recommendations provided herein considered in the final designs and implemented during the construction phase, where applicable and as appropriate. III. PRELIMINARY RECOMMENDATIONS Fine and minor remedial grading techniques will be necessary in order to achieve final finish design subgrade elevations, and improve existing subgrade soil and base materials conditions beneath the planned new paving improvements. All fine and remedial subgrade soil preparations, and paving operations should be completed in accordance with Chapter 18 (Soils and Foundations) and Appendix "J" (Grading) of the 2016 California Building Code (CBC), City of Carlsbad Ordinances, the Standard Specifications for Public Works Construction (Green Book), and the requirements of the following sections wherever applicable. 1. Pavement Subgrade Preparations: Minor fine and remedial grading and recompaction of upper subgrade soils, and base layer where it is exposed, will be required underneath the proposed new paving improvements in order to construct a stable structural section under the proposed new HMA (AC), PICP and PCC paving surfaces. Specific recommendations should be given in the field by the project geotechnical engineer at the time of sub grade and base preparations. However, subgrade preparations consisting of in-place ripping and recompaction (R&R) to a minimum depth of 12 inches should be anticipated. Subgrade soils (and base materials, where exposed) within the project limits should be reworked in-place, moisture conditioned to slightly (2%) above the optimum moisture levels and compacted to a minimum 95 percent (based on ASTM D 1557) compaction levels, tested and approved by the project geotechnical consultant. Subgrade soils under curb and gutters, should also be compacted to minimum 95 percent compaction levels, while subgrade under sidewalks should be compacted to a minimum of 90 percent compaction levels, unless otherwise specified. Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad September 28, 2018 Page3 2. Preliminary HMA (AC) Structural Section Design: The following pavement structural section design is based on a conservatively assumed sub grade R-value of 5 and design traffic index (Tl) of 5. A minimum section of 4 inches HMA (AC) over 6 inches of Class 2 crushed aggregate base (AB) or the minimum section required by the City of Carlsbad, whichever is more, will be required when a lesser pavement section is indicated by design calculations, as presented in the table below (an equivalent full depth AC is also provided): Design R-value 5 I I BMA (AC) over AB 4" AC over 7.5" AB Desil?Il Traffic Index ffl=S) I Equivalent Full Depth BMA (AC) 7.25" AC HMA (AC) = Hot Mix Asphalt Concrete. AB = Aggregate Base. Pavement design calculations are attached with this report as an Asphalt Pavement Structural Section Design Calculation Sheet. Maximum lift for asphalt concrete shall not exceed 3 inches, unless otherwise approved. HMA (AC) layers greater than 3 inches thick should consist of a binder/base course (¾-inch aggregate) and a finish top course (½-inch aggregate) topcoat, spread, placed and compacted as required by the City of Carlsbad ordinances, and in accordance with the applicable local codes and Caltrans standards. Class 2 aggregate or recycled base (AB) may be used and shall meet or exceed the requirements set forth in the current California Standard Specification (Caltrans Section 26- 1.02A). Base materials should be compacted to a minimum 95 percent of the corresponding maximum dry density (ASTM D 1557). Subgrade soils beneath the asphalt paving surfaces should also be compacted to a minimum 95 percent of the corresponding maximum dry density within the upper 12 inches. Base materials and subgrade soils should be tested for proper moisture and minimum 95 percent compaction levels and approved by the project geotechnical consultant prior to the placement of the base or asphalt layers. 3. Asphalt Overlay and Resurfacing: Cold milling, grinding and overlay of existing pavements in the transition areas are proposed as shown on the project improvement plans. Form this purpose, existing asphalt pavements should be neatly saw cut, where shown on the project plans, and a minimum 2 feet wide strip along the edge of existing asphalt grinded to a minimum depth of 2 inches for an overly placed as part of new asphalt paving to providing a smooth transition. Upon completion of grinding, exposed surfaces receiving overlay should be examined for pavement evaluation and the need for application of pavement fabric to disallow reflective cracking. Pavement fabric (Pertomat or approved equal), if and where necessary, should be properly placed over the exposed pavement cracks prior to resurfacing in accordance with the manufacturer's recommendations and project specifications. Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad September 28, 2018 Page4 I Surfaces of grinded asphalt should be prepared to the satisfaction of the project geotechnical engineer and city inspector prior to the placement of the tack coat and/or pavement fabric. All materials, and construction procedures should comply with the City of Carlsbad Ordinances and Standard Specifications For Public Works Construction (Green Book). 4. Permeable Interlocking Concrete Pavers (PICP): Permeable Interlocking Concrete Pavers (PICP) are incorporated into the new improvements apparently as a part of the project storm water BMPs. The project site is underlain by sandy soil (SM/SP) which typical have modest to good infiltration characteristics. Based on our past experience with similar soils, underlying soil profile may be characterized as Hydrologic Soil Group B/C (based on San Diego Hydrology Manual classification). However, the PICP structural section designs should provide adequate storage capacity consistent with the project stonnwater requirements, and nearby structures and improvements properly protected from excessive saturation and softening of bearing and sub grade soils. For this purpose, deepened curb or concrete edge restraints extending a minimum 12 inches below the finish subgrade levels (below bottom of No 57 rock base) along the edges of impacted structures and site improvements should be considered. Considering sandy characteristics of the onsite site soils, the proposed PICP section of31/a- inch, PICP over a minimum of 2 inches of ASTM No. 8 bedding course/choke stone over a minimum 8 inches of ASTM No. 57 stone base course underlain with a Mirafi 140N soil separation fabric over a minimum of 12 inches of 95 percent compacted subgrade (per ASTM D1557), as show on the project plans, are considered acceptable at this time subject to verification and confirmation at the time of sub grade preparations. Bedding course/choke stone and base course stone should also be well compacted, consolidated and interlocked (avoid crushing the underdrain pipes) with heavy construction equipments. ASTM No. 8, No. 9 or No. 89 should be used for joint materials depending on the joint size and per manufacturer recommendations. Gradation requirements for ASTM No. 57, No. 8, No. 89 and No. 9 are as follows: Sieve II Percent Passing I Size l I I No.57 No.8 No.89 No.9 l ½" 100 1" 95 to 100 ½" 25 to 60 100 100 3/s" 85 to 100 90 to 100 100 No.4 0 to 10 10 to 30 20 to 55 85 to 100 Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad September 28, 2018 Page5 I Sieve II Percent Passing I Size I I I No.57 No.8 No.89 No.9 No.8 0 to 5 0 to 10 5 to 30 10 to 40 No. 16 0 to 5 0 to 10 0 to 10 No. 50 0 to 5 0 to 5 5. Concrete Curb and Gutters, and PCC Sidewalks Subgrade preparations and base section per structural section design will also be required for all curbs and gutters (including cross gutters). Provide a minimum of 6 inches of Cal trans Class 2 base (AB) materials under all curb and gutters, unless otherwise noted or approved. Base layer under curb and gutters should be compacted to a minimum of95 percent, while subgrade soils under curb and gutters and sidewalks should be compacted to a minimum of 90 percent compaction levels, unless otherwise specified. Base layer will not be required under sidewalks in case of very low expansive soils. Concrete sidewalks should be a minimum of 4 inches thick reinforced with 6x6/10x10 welded wire mesh carefully placed mid-height in the slab, unless otherwise noted or approved. Reinforcements lying on subgrade soils will be ineffective and shortly corrode due to lack of adequate concrete cover. Reinforcing bars should be correctly placed extending through the construction joints tying the slab panels. In construction practices where the reinforcements are discontinued or cut at the construction joints, slab panels should be tied together with minimum 18 inches long #3 dowels at 18 inches on centers placed mid-height in the slab (9 inches on either side of the joint). Also, provide "tool joint" or "softcut" contraction/control joints spaced 10 feet on centers maximum. The larger dimension of any panel shall not exceed 125% of the smaller dimension. Tool or cut as soon as slab will support weight, and can be operated without disturbing the final finish which is normally within 2 hours after final finish at each control joint location or 150 psi to 800 psi. Tool or softcuts should be a minimum of 1-inch but should not exceed 1 ¼-inch deep maximum. In case of softcut joints, anti-ravel skid plates should be used and replaced with each blade to avoid spalling and raveling. A void wheeled equipment across cuts for at least 24 hours. Joints shall intersect free-edges at a 90° angle and shall extend straight for a minimum of 1 ½ feet from the edge. The minimum angle between any two intersecting joints shall be 80°. Align joints ofadjacentpanels. Also, align joints in attached curbs with joints in slab panels. Provide adequate curing using approved methods (curing compound maximum coverage rate = 200 sq. ft./gal.). Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad IV. ENGINEERING OBSERVATIONS AND TESTING September 28, 2018 Page6 All subgrade preparations, base materials placement and compaction, as well as HMA, PICP and PCC pavement constructions should be continuously observed and tested by the project geotechnical consultant and presented in daily field and final pavement compaction reports. Testing procedures will also aid the project contractor to achieve the specified soils moisture contents and compaction levels. The nature of finish subgrade soils and final pavement designs shall also be confirmed by performing appropriate sampling and laboratory testing and presented in the final subgrade compaction reports. V. LIMITATIONS Preliminary recommendations provided herein are based on assumed design values provided for planning and cost estimating purposes and shall be verified by actual field sampling and testing at the time demolitions and construction. Revised pavement structural sections may be necessary and should be anticipated. The future performance of the PICP pavement BMP facility, as currently planned at the project site, is difficult to predict with certainty due to numerous unpredictable factors, such as amount of seasonal and annual rainfall, actual infiltration rates, irrigation and maintenance of drainage systems. In order to reduce potential impacts on the adjacent building foundations, structures, improvements, or problems associated with the planned BMP facility, the following recommendations are presented: Provide periodic maintenance of the PICP pavement BMP facility, as necessary, and monitor nearby structures and improvements. Should any saturated ground or related conditions occur, the project civil engineer and geotechnical consultants should be immediately notified. Mitigation measures including installations of an underdrainage system consisting of a perforated pipe (minimum 4-inch Sch. 80) placed in a trench (minimum 12 inches wide by 12 inches deep) surrounded with ¾-inch crushed rocks all wrapped in filter fabric (Mira:fi 140N) may become necessary, and cannot be ruled out. -Provide landscaping consisting of drought resistant plants and monitor the amount of irrigation water. Irrigation should be limited to the amount of water necessary to sustain plant life. A landscape architect should be consulted, in this regard. The actual performance and impact of the recently required private PICP pavement BMP facilities can only be evaluated through time. Additional recommendations or future repairs and modifications to the system may be necessary, in the event adverse or consequential conditions manifest themselves. This will require proper disclosure to any owners and all interested/affected parties. However, in no respect do we guarantee or warrant the performance of the private PICP pavement BMP facilities. Preliminary Pavement Section Design And Plan Review, Proposed Lanikai Main Gate Improvement Project, 6550 Ponto Drive, Carlsbad September 28, 2018 Page7 Should any questions arise concerning this report, please do not hesitate to contact this office. Reference to our Project No. GI-18-08-147 will help to expedite our response to your inquiries. We appreciate this opportunity to be of service to you again. §1'1§ Geotechnical Solutions, Inc. Attachment: Asphalt Pavement Structural Section Design Calculation Sheet Distribution: Addressee (2, e-mail) Mr. Brian Regan, Hofman Planning & Engineering (2, e-mail) §1'.I§ GEOTECHNICAL SOLUTIONS. INC, ASPHALT PAVEMENT STRUCTURAL SECTION DESIGN CALCULATION SHEET Proposed Lanikai Main Gate Improvement Project Project No. FC-18-08-147 September 21, 2014 I. HMA (AC) Over Class 2 Aggregate Base Design: Data: SubgradeR = 5; Tl= 5; Minimum Section = 4" HMA over 6" Class 2 base. GEToT = 0.0032 x TI x {100 -R) = 0.0032 x 5 x (100 -5) = 1.52 GFAc (HMA): From Cal Trans 2006 Edition, Table #633. l = 2.54 Gfac =(llic + 12) X GFAc = 4 + 12 X 2.54 = 0.85 GEAB = GETor -GEAc =1.52 -0.85 = 0.67 HAB = (GEAB + GFAB) X 12 = (0.67 + 1.1) X 12 = 7.3 SAY 7.5 inches Use Minimum 4 Inches HMA (AC) Over 7.5 Inches Class 2 Base Over 95% Compacted Sub rade. II. Full Depth HMA (AC) Design: Data: Subgrade R = 5; Tl= 5.0. GFAc (HMA): From Cal Trans 2006 Edition, Table #633.1 = 2.54 GFAB:= 1.1 GEAB = HAe X GFAB = (7.5 + 12) X 1.1 = 0.69 Equvl. GEAc = GEAB = 0.69 Equvl. fuc = ((GEAB = GEAc) + GFAc) X 12 = (0.69 + 2.54) X 12 = 3.25 SAY 3.25 inches TOT Equvl. fuc =(fuc + Equvl. fuc) = 4 + 3.25 = 7.25 inches §M§ Geotecbnical Solutions. Inc.