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December 6, 1994
Mr. Bernist Mazur
DIAMOND EAST PARTNERS
2050 Valderas Road
Glendale, CA 91208
SUBJECT: Geotechnical Review of Precise Grading Plan, Foundation Plan and
Foundation Details for Lot 26, Tract 47851, Crystal Ridge Estates, Diamond
Bar, California HGE1 Project No. 91-02-0109A-26
REFERENCES:
Dear Mr. Mazur:
1) Precise Grading Plan for the Subject Lot, Undated, Prepared by
Lanco Engineering.
2) Foundation Plan, Sheet 7, Dated November 4, 1994, and Details,
Sheet D-1, Dated September 4, 1994, for the Subject Lot, Prepared
by R. Gould and Associates, Inc.
3) "Geotechnical Report of Rough Grading for Lots 1-17 and 20-48,
Vesting Tentative Tract 47851, Diamond Bar, California," Dated
October 11, 1994, by HGEI, Project No. 91-02-0109A.
In response to a request from Mr. Richard Gould and your authorization we have
reviewed the referenced precise grading plan, foundation plan and foundation details for
Lot 26 of Tract 47851.
The referenced plans and details were reviewed from a geotechnical standpoint for
conformance with our recommendations only. These plans and details were not reviewed
as to the accuracy of dimensions, measurements, calculations or any non-geotechnical
portion of the design.
Based upon our review it appears that the referenced plans and details are in general
conformance with our previous recommendations. During this review the following items
were noted:
Batavia Business Center, 1938 North Batavia Street, Suite N, Orange, CA 92665 (714) 637-3093 ® (800) 924-7645 • FAX (714) 637-3096
DIAMOND EAST PARTNERS
Project No. 91-02-0109A-26
December 6, 1994
Page 2
No significant changes to the building pad elevation and/or adjacent descending
slopes are currently planned. The homeowner should be informed that future
grading to alter the pad and/or slopes should not be performed without review by
a geotechnical consultant familiar with rough grading of the tract. In addition, the
homeowner should be informed of the importance of slope landscaping,
maintenance and erosion control and should be provided with the guidelines that
were appended to the referenced rough grading, report (Appendix C).
2. The northerly side of the proposed structure is located at approximately the toe of
the existing ascending side yard slope. In order to provide a five -foot -wide access
to the rear yard the toe of the slope will need to be removed and replaced with a
five -foot -high retaining wall. The overall height of the slope is approximately 18
feet. In our opinion, from a geotechnical standpoint, the H/2 setback as required
by the Uniform Building Code is not necessary. However, the minimum setback
between the house and the retaining walls should be five feet as shown on the
precise grading plan.
3. The proposed structure is located at approximately the top of descending slopes
in the front and along the southerly side of the lot. Adjacent to the top of these
slopes the house footing should be deepened as necessary to provide a minimum
distance of five feet between the outside edge of the footing and the slope face.
4. Preliminary laboratory testing indicates that the on -site surface soils have a medium
expansion potential and moderate concentrations of water-soluble sulfate as
defined by the Uniform Building Code. As a result the floor slab design should be
revised to agree with Foundation/Slab Type III as presented on Table A of the
referenced rough grading report (Ref. 3). Also, provision of Table 19-A-3 of the
Uniform Building Code (1994 Edition) apply to all concrete in contact with the soil.
The expansion potential and sulfate concentrations should be confirmed by
additional sampling and testing at the time of precise grading.
As requested by Mr. Gould, we have stamped and signed three copies of the precise
grading plan and have returned them to him along with copies of this letter.
DIAMOND EAST PARTNERS
Project No. 91-02-0109A-26
December 6, 1994
Page 3
We trust that this letter/report is adequate for your current needs. If you have any
questions or require additional assistance, please call.
Very truly yours,
HARRINGTON GEOTECHNICAL ENGINEERING, INC.
Prepared By: Reviewed By:
Don P. Harrington, Sr., P.E.
President
Distribution: Addressee - 2
R. Gould & Associates - 3 (with copies of Precise Grading Plan)
Q\D0CS\DBAR\0109A26. RV W