Loading...
14820 Kelty Ct - Soils Report I ,4 4,7 ( 6 ii/ May 9, 2017 John Welch c/o Land Design 351 Thomas St., Ste. A Pomona, CA 91766 Subject: Proposed Retaining Walls 14820 Kelty Ct. Chino Hills, CA 91709 Job No. 17-041 References: Duco Engineering, Inc. (1998, November 9). "Proposed Swimming Pool, Welch Residence, Lot 12, Tract No. 15723, 14820 Kelty Court,Chino Hills,California, Job No.: 98-199".Soils Report. John R. Byerly, Inc. (1995, November 7). "Geotechnical Investigation, Tentative Tract 15723, Van Daele Development Corp.". Soils Report. Mr. Welch: In accordance with your request this firm has reviewed the proposed site plan and applicable documentation as available from the City of Chino Hills, and performed the necessary analysis to provide the retaining wall design and construction recommendations contained herein. These recommendations are premised upon the conclusions and recommendations contained in the tract reports as prepared by John R. Byerly, Inc., as well as prior reporting by this firm. Please consult this documentation, and all preceding references, for further information. Additional reference material included the site plan provided by you, the client. Review and Observation According to the above reference materials, the subject lot is composed of a cut lot capped with 3 feet of certified, compacted fill, with siltstone and sandstone immediately underlying. Adjacent lots vary in elevation, with a 15 to 18 foot high 2:1 ascending slope to the north and west of the lot, and a —9 foot high descending slope to the south and west. Observations made on-site for the preparation of this report revealed consistency with conditions previously denoted in referenced reporting, with the addition of the since completed swimming pool and hardscape, and additional landscaping and vegetation growth. Duco Engineering, Inc. Job No. 17-041 Page 2 The recommendations contained in this report are valid only during the construction of the retaining wall and are not currently considered applicable to any future development. Additional or future construction should be geotechnically evaluated based on site-specific plans. Geotechnical Feasibility Construction of a retaining wall is considered feasible from a geotechnical standpoint based on the implementation and incorporation of the recommendations contained herein into the design and construction. Recommendations contained in this report are based upon the file review, limited testing requested and our observations of the site at the time of sampling. Recommendations assume a maximum wall height retaining 6 feet. Soil Expansivity In accordance with the current CBC, a representative sample of soils in the area of proposed construction was obtained, and testing was conducted to obtain the Expansion Index (E.I.) of the sample. This test corresponds to qualitative scale of soil swelling/shrinking due to changes in moisture. With an Expansion index of 114 obtained through testing, on-site soils are considered highly expansive. Soil Corrosivity Representative onsite soils were tested to evaluate corrosivity to concrete. The results of this test are as follows: Soluble Sulfates Test CA 417 117 ppm As such, the onsite soils are considered severely corrosive to concrete. All concrete in contact or close proximity to soil shall consist of Type II cement with a normal compressive strength and a 0.5 water-cement ratio. Wall Design and Construction Recommendations It is recommended that walls be backfilled with select backfill, granular in nature and having a tested sand equivalency greater than 30 (preferably either clean sand or gravel). Walls backfilled with select material shall be designed to accommodate active earth pressures of 35 pcf for level backfill, and 48 pcf where retaining a 2:1 ascending slope. Should on-site soils be used to Duco Engineering, Inc. Job No. 17-041 Page 3 backfill the proposed walls, their expansive nature dictates that active earth pressures of 100 pcf level, and 130 pcf inclined at 2:1, be used in the design. Backfill material accounted for in the design of the wall must be delineated on the project plans in order to be approved by this firm. Regardless of composition, all backfill shall be compacted to a minimum of 90% of its maximum dry density; wall construction shall conform to the attached retaining wall guidelines. Retaining wall foundations may bear into competent bedrock or certified compacted fill, though a cold joint must be placed in the wall section at each place where there is a transition between bedrock and fill along the footing bottom. These footings shall be embedded a minimum of 18 inches into approved material, and may be designed for an allowable bearing value of 2000 psf, with no increase allowed for depth or width. This value may be increased by 33.3% when undergoing transient loading. Lateral resistance may be taken at 350 psf/ft, up to 1500 psf, with a coefficient of friction of 0.4 where concrete is poured in direct contact with approved subgrade material. Wall reinforcement shall conform with the parameters set in the current CBC, as well as the currently adopted edition of ACI 318, and any additionally pertinent local codes. Footing reinforcement shall conform with WRI design guidelines, using a P.I. (Plasticity Index) of 32. Any soils used for fill or that are disturbed during the demolition of the existing improvements shall be compacted in accordance with the current building code, to a minimum compaction of 90% of the maximum density, as determined by ASTM D1557. This firm shall provide inspection and approve the retaining wall excavation and drilled shaft borings prior to placing any steel reinforcement or concrete, in order to verify the anticipated soils conditions. Site Recommendations The homeowner should be made aware that some additional amount of movement is common in expansive soil and is expected for the site, as well as most natural and man-made fill building pads. Additionally, some amount of slope creep is to be expected. Rear yard improvements are not generally considered structural; however, we do recommend that walkways, patios, garden walls, and other landscape features be constructed with the ability to accommodate the effects of expansive soil. Separation of flatwork and distortion of other landscaping improvements may occur. Typical remediation includes construction joints, flexible pavers and structures, and additional reinforcement. The resident is responsible for proper maintenance, landscaping, and irrigation. Landscaping improvements must not cause surface water to collect adjacent to any foundation, causing saturated soils adjacent to the foundation. Planters adjacent to the building should be avoided or at least properly designed to reduce the amount of water penetration adjacent to Duco Enaineerina, Inc. Job No. 17-041 Page 4 footing subgrades, thereby reducing moisture related foundation damage. Any planned area drains should be recessed below grade to allow the free flow of water into the drain inlet. Flatwork and concrete walks should be at an elevation such that they will not obstruct the flow of surface water. Water should not be allowed to pond or flow at or over the top of any slope. Irrigation methods should promote uniformity of moisture. It should be noted that, upon our site inspection, overwatering was observed. Overwatering and underwatering must be avoided. Heavy irrigation and inadequate runoff gradients can create moisture problems. Maintaining adequate surface drainage and controlled irrigation will significantly reduce the potential for nuisance-type moisture issues. Additionally, it is recommended that all flatwork be constructed so that a minimum of 1/2 inch exists between the concrete flatwork and structures, such as residential buildings, retaining walls and sound privacy walls. Closure Site preparation, fill material removal and recompaction, foundation and soil preparation for construction should also be reviewed by a geotechnical engineer. These additional services are not a part of this report and are provided at an additional cost. The findings in this report are based and prepared in accordance with generally accepted geotechnical engineering practices. Should you have any questions with regard to this report or the recommendations contained herein, please contact this office. Respectfully submitted, DUCO ENGINEERING, INC. Approved by: QROFES$ip J',meg. Collett Frank C. Stillman, GE ;e %Pet GP Pr.' ngineer r41.,CANF°�\P, • •11Iiiui i' I ' 06.05.17 ■Ilii■ LANDSCAPE ARCHITECTURE URBAN AND OPEN SPACE PLANNING D.RODNEY TAPP,LANDSCAPE ARCHITECT,CA 1483 Correction List Building and Safety- Clarified handrail and stair dimension, drainage, slope on concrete,basin existing,proposed legend, and wall excavation detail. Engineer's details provided in sheet 24"x36" format and signed. Soils engineer signed plans and reviewed structural details,engineer stamped and signed plans. 351 SOUTH THOMAS STREET, SUITE A, POMONA, CALIFORNIA 91766 (909) 622-1472 FAX (909) 622-0917 www.Iandesigninc.com