HomeMy WebLinkAboutCT 00-06; BRESSI RANCH; GEOTECHNICAL RECOMMENDATIONS REGARDING CONCRETE FLATWORK UNDERLAINMENT; 2004-04-01cr00. e7(
Leighton and Associates, Inc.
A LEIGHTON GROUP COMPANY
April 1, 2004
Project No. 971009-009
To: Lennar Communities
1525 Faraday Avenue, Suite 300
Carlsbad, California 92008
Attention: Ms. Kristine Zortman
Subject: Geotechnical Recommendations Regarding Concrete Flatwork Underlainment for
Poinsettia Lane, El Fuerte Street, El Camino Real, and Palomar Airport Road, Bressi
Ranch, Carlsbad, California
Based on our understanding of the City of Carlsbad requirements and the anticipated geotechnical
conditions along the Bressi Ranch Assessment District streets (i.e. Poinsettia Lane, El Fuerte Street, El
Camino Real, and Palomar Airport Road), aggregate base material is not required beneath the proposed
concrete flatwork. However, if highly expansive claystone or fill soils are encountered, procedures to
minimize the affects of expansive soil related distress to the flatwork should be considered. Mitigation
methods include placing the subgrade soils at an elevated moisture content of 4 to 6 percent over the
optimum moisture content, compacting the subgrade soils to a maximum 87 to 88 percent relative
compaction, placement of 6 inches of Class 2 aggregate base (compacted to a 90 percent relative
compaction), or a combination of the methods listed. A representative of Leighton and Associates should
evaluate the concrete flatwork subgrade soils before the subgrade soils are graded to determine if expansive
soils are present. It should noted that even if one or more of the mitigation measures are performed, heaving
of the concrete flatwork may still occur. However, the mitigation measures will help to minimize the amount
of heaving.
If you have any questions regarding our letter, please contact this office. We appreciate this opportunity to
be of service.
Respectfully submitted,
LEIGHTON AND ASSOCIATES, INC.
Randall K. Wagner, CEG 1612
Senior Associate
Distribution: (4) Addressee
(1) Lennar Communities, Attention: Mr. Jim Urbina
(1) J. T. Kruer, Attention: Chuck Knight
3934 Murphy Canyon Road, Suite B205 • San Diego, CA 92123-4425
858.292.8030 • Fax 858.292.0771 • www.leightongeo.com