HomeMy WebLinkAboutCT 97-14; MARIANO; INTERIM REPORT OF TESTING AND OBSERVATION SERVICES DURING SITE GRADING; 2000-03-20GEOCON
INCORPORATED
Project No. 06195-12-03
March 20, 2000
Standard Pacific Homes
9335 Chesapeake Drive
San Diego, California 92123
Attention: Mr. Thomas C. Farrar
Subject: MARIANO
CARLSBAD, CALIFORNIA
GEOTECHNICAL CONSULTANTS 0
SLOPE REMEDIAL GRADING: LOTS 125 THROUGH 133
Reference: Interim Report of Testing and Observation Services During Site Grading, Mariano,
Lots 1 Through 14, 19 Through 41, 43, 44, 75 Through 86, 88 Through 103, 105
Through 136 and 138 Through 151, Carlsbad, California, prepared by Geocon
Incorporated, dated February 25, 2000.
Gentlemen:
In accordance with the request of Ms. Anne Hysong, City of Carlsbad Planning Department, this
letter has been prepared to present a discussion of the reasons for grading within the slope area
located at the rear of Lots 125 through 13 3 within the Mariano residential development.
During the early phases of planned lot grading along the east side of the SDG&E easement, it became
apparent that the slope, originally to remain natural, should be remediated for the reasons as
discussed below.
Lots 125 -129
The landslide originally mapped along this slope and to the north of these lots was observed during
grading to extend further to the south. The landslide was relatively shallow in depth in the area of
Lots 125 through 129. The slope was severely eroded with gullies of up to 10 feet deep. In our
opinion, the landslide debris presented a serious potential long-term stability issue regarding these
lots. For this reason, the slope required regrading to remove the landslide debris to reconstruct a
stable slope. The slope was regraded to essentially the original inclination of approximately 3: 1
(horizontal :vertical).
Lots 130 -133
Within this area it was evident that previous grading (agricultural?) had denuded the natural
vegetation. Hence, the slope had experienced severe erosion, with gullies of up to 6 feet deep. This
condition presented a serious potential erosion/stability issue with respect to the bordering residential
lots. For this reason, it was evident that some form of remedial grading would be required to infill the
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deeper erosional features at a minimum. The concern was that on a long-term basis, the erosion
would progress up slope and adversely impact the residential improvements within the lots.
Ultimately, the slope was regraded, including infilling all the gullies and track-walking the finish
slope with a D-8 bulldozer. Final slope inclination essentially remained at the original 3: 1
(horizontal:vertical).
Details of the grading as discussed above are presented in the referenced report, copy attached, in the
section entitled Slopes, (page 3).
If you have any questions regarding this correspondence, or if we may be of further service, please
contact the undersigned at your convenience.
Very truly yours,
enclosure: Referenced report dated February 25, 2000.
DFL:lek
( 1) Addressee
(1) Jack Henthorn & Associates
Attention: Mr. Jack Henthorn
Project No. 06195-12-03 -2 -March 20, 2000