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Home My WebLink AboutCT 03-02; CARLSBAD RANCH PA 5; GRADING PLAN REVIEW AND SUPPLEMENTAL GEOTECHNICAL RECOMMENDATIONS LETTER VILLAS 50-52, HOTEL 2; 2007-09-11 RECEIV MILE SEP 132007 CITY OF CALSBAI) ENCINEF11NC I3E'A RIM ENT CM&I DIVISION Leighton and and Associates, Inc. A LEIGHTON GROUP COMPANY September 11, 2007 Project No. 040575-005 To: Grand Pacific Resorts, Inc. 5900 Pasteur Court, Ste. 200 Carlsbad, CA 92008 Attention: Mr. Tim Stripe Subject: Grading Plan Review and Supplemental Geotechnical Recommendations Letter, Carlsbad Ranch Planning Area No. 5, Villas 50 through 52, Carlsbad, California References: Excel Engineering, 2007, Grading and Erosion Control Plans for Carlsbad Ranch, Planning Area, Resort site - Villas 50-52, Carlsbad, California, Project No. CT 03- 02, 8 Sheets, Drawing No. 428-9D, dated August 28, 2007 Leighton and Associates, Inc., 2005, Geotechnical Investigation, Proposed 53 Acre Resort Development, Phase 1, Carlsbad Ranch, Planning Area No. 5, Carlsbad, California, Project No. 040575-005, dated April 11, 2005 2006, As-Graded Geotechnical Report of Rough and Fine Grading, Hotel One, Resort and Conference Facilities, Sales Building, and Villas No. 53-56, Lots 10 and 11, and a Portion of Lot 1, Grand Pacific Carlsbad, Carlsbad, California, Project No. 040575-005, dated August 2, 2006 Introduction In accordance with your request and authorization, we have prepared this letter to address the City of Carlsbad grading plan review comments for the proposed expansion of the Grand Pacific Carlsbad Resort Villas 50 through 52 located in Carlsbad, California. In addition, we have performed a review of the referenced grading plans prepared by Excel Engineering dated August 28, 2007 relative to the geotechnical recommendations presented in the project geotechnical reports referenced above (Leighton, 2005 and 2006). Our review was performed to identify potential conflicts with the referenced geotechnical reports. 3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425 858.292.8030 • Fax 858.292.0771 • www.leightongeo.Com 040575-005 Response to City of Carlsbad Grading Plan Review Comment Provide a letter/report by the soils engineer on preparation of area of desilting basin to remove unsuitable materials and prepare for construction. We recommend that any silt, saturated and/or loose and disturbed soils be removed to competent material within the limits of the desilting basin prior to the placement of any fill soils. Additional recommendations concerning the grading and construction of the site of the proposed Villas 50 through 52 are presented below. Grading Plan Review Comments We have performed a geotechnical review of the grading plans for the Grand Pacific Carlsbad Resort Villas 50 through 52 project. The purpose of our geotechnical review was to evaluate if the plans have been prepared in general accordance with the project geotechnical recommendations that have been presented in our reports (Leighton, 2005 and 2006). Based on our geotechnical review of the grading plans and the geotechnical reports, the plans appear to have been prepared to general accordance with the project geotechnical recommendations. However, the following items should be noted: Sheet 1, No. 6 of the Work To Be Done Section: The project as-graded geotechnical report dated August 2, 2006 (Leighton, 2006) should also be referenced. Addendum Geotechnical Recommendations The building pad for the proposed Villas 50 through 52 was sheet-graded during the rough grading operations at the site. The following addendum geotechnical recommendations should be followed during the grading and construction of Villas 50 through 52 and the associated improvements; Since the completion of the rough grading operations was longer than 6 months ago, we recommend that the upper 12 inches of the Villas 51 and 52 building pads be scarified, moisture conditioned at least 2 percent over the optimum moisture content, and recompacted to a minimum 90 percent relative compaction (based on ASTM Test Method D1557) prior to the placement of additional fill or structural improvements. To mitigate the transition from formation to fill conditions, we recommend that the Villas 50 building pad be overexcavated 5 feet and recompacted. The lateral extent of overexcavation should extend 10 feet outside the building perimeter. We recommend that any silt, saturated and/or loose and disturbed soils be removed to competent material within the limits of the desilting basin prior to the placement of any fill soils. -2- Leighton il gak Le~`CEG. 161 Director of Geology Distribution: (2) Addressee (1) City of Carlsbad, Attention: Mr. Patrick Vaughn (1) JPM Design Management, Attention: Mr. John Mattox (1) Hazard Construction, Attention: Mr. Bob Chateau (1) Excel Engineering, Attention: Mr. Kurt Wilkins (1) MTGL, Attention: Mr. Eduardo Dizon 040575-005 Based on the grading plans, the existing outlet pipe for the desilting basin will be partially removed and a cleanout structure constructed to the southwest of Villa 50. All of the existing fill (as well as the pipe) should be removed and replaced with 90-percent compacted fill. We recommend a minimum horizontal setback distance from the face of slopes for all structural footings and settlement-sensitive improvements. This distance is measured from the outside edge of the footing, horizontally to the slope face (or to the face of a retaining wall) and should be a minimum of H/2, where H is the slope height (or retaining wall) in feet, to a maximum of 15 feet along 2:1 slopes. For steeper slopes, case-by-case recommendations should be provided. Please note that the soils within the structural setback area possess poor lateral stability, and improvements (such as retaining walls, sidewalks, fences, pavements, etc.) constructed within this setback area may be subject to lateral movement and/or differential settlement. A representative of Leighton should observe and perform field density testing during the building pad reprocessing and desilting basin removal and recompaction operations. A Leighton representative should also document the foundation excavations of the Villas and any other grading or construction operations within or adjacent to the proposed buildings. A final as- graded report should be prepared documenting the grading operations and providing additional geotechnical recommendations if warranted. If you have any questions regarding this letter, please do not hesitate to be of service. We appreciate Us opportunity to be of service. Respectfully submitted, LEIGHTON AND ASSOCIATES, INC. -3- Leighton RECEIVED 4: HMAR 2 77 Leighton and Associates, Inc. .. L ENGI'OF CARSBAD kIENT A LEIGHTON GROUP COMPANY 6W DIVI-SION March 19, 2007 Project No. 040575-005 To: Grand Pacific Resorts, Inc. 5900 Pasteur Court, Ste. 200 Carlsbad, CA 92008 Attention: Mr. Bruce Zelenka Subject: Grading Plan Review and Supplemental Geotechnical Recommendations Letter, Carlsbad Ranch Planning Area No. 5, Phase 1, Hotel 2, Carlsbad, California References: . Excel Engineering, 2007, Grading Plans for Carlsbad Ranch Area No. 5, Resort Site, Hotel 2-Phase 1, Carlsbad, California, Project No. CT 03-02, 9 Sheets, Drawing No.. 428-9B, dated March 9, 2007 Leighton and I Associates, Inc., 2005, Geotechnical Investigation, Proposed 53 Acre Resort Development, Phase 1, Carlsbad Ranch, Planning Area No. 5, Carlsbad, California, Project No. 040575-005, dated April 1, 2005 2006, Geotechnical Recommendations for Subgrade and Base, Proposed Interlocking Payers, Carlsbad Ranch Resort, Planning Area 5, Carlsbad, California, Project No. 040575-005, dated April 5, 2006 2007, As-graded Geotechnical Report of Rough and Fine Grading, Hotel #2 and a Portion of the Lot 15 Parking Area, Grand Pacific Carlsbad, Carlsbad, California, Project No. 040575-005, dated March 8, 2007 In accordance with your request and authorization, we have performed a geotechnical review of the referenced grading plans for the proposed expansion of the CarIsbad Ranch Hotel in Carlsbad, California. Our review was performed to identify potential conflicts with the referenced geotechnical reports. Based on our review, we are of the opinion that the plans were prepared in general conformance with the referenced soils reports. 3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425 858.292.8030 • Fax 858.292.0771 • www.leightongeo.com LEIGHTON AND ASSOCIATES, INC. Sean Colorado, GE 2507 Director of Engineering 040575-005 We have been informed that .the owner intends to retain another geotechnical firm to provide a majority of the geotechnical services that are needed for the project. We understand that our services during construction will be limited to the Hotel 2 Building itself. All other improvements are considered to be outside the area of our responsibility. The owner should verify that the soils engineer and engineering geologist of record for the remainder of the site have affected the.proper Transfer of Responsibility per Section 3317.8 of the 2001 California Building Code. The Transfer of Responsibility letter should be signed by both a Geotechnical Engineer and a Certified Engineering Geologist. Because of the amount of ground water observed during grading, it is imperative, that the new geotechnical consultant ensure that all subdrainage system throughout the site are properly connected to protected outlets. We shall not be responsible for adverse performance of improvements that may be affected by work for which we have not provided observation and testing through completion of construction. If you have any questions regarding our letter, please do not hesitate to be of service. We appreciate this opportunity to be of service. Respectfully submitted, Distribution: (2) Addressee (1) City of Carlsbad, Attention: Mr. Patrick Vaughn (1) JPM Design Management, Attention: Mr. John Mattox (1) Hazard Construction, Attention: Mr. Bob Chateau (1) Excel Engineering, Attention: Mr. Kurt Wilkins (1) MTGL, Attention: Mr. Eduardo Dizon Leighton IPA